Alkaline earth metals chemical

Introduction :
Alkaline earth metals are beryllium, magnesium, strontium, calcium, barium, and radium. These are the chemical elements that occupy the second column in the periodic table. In olden days when substances were insoluble in water and unchanged by fire they were referred to as earths. Thus the name uses of alkaline Earth metals.

Alkaline earth metals:

The alkaline-earth elements have a grey-white lustre when freshly cut. This lustre is tarnished readily when exposed to air. These metals are good conductors of electricity and highly metallic and. Beryllium is hard enough to scratch glass.

http://www.britannica.com/EBchecked/topic/53345/bariumBarium is the least hard of them all. The elements in this group have higher melting points and boiling points than those of the corresponding alkali metals;  and beryllium has the highest boiling and melting points(MP 1,283° and bop about 2,500°) and magnesium has the lowest boiling and melting point in this group (MP 650° C and bp 1,105° C)

Occurrence in Nature

• Magnesium and calcium are essential to all living organisms and found in abundance in several compounds.While calcium is needed for bone and teeth formation, magnesium is needed for the intercellular processes and enzyme formation in the body.
• Beryllium is least soluble and is very rarely found in nature. It is a toxic metal.

• Strontium and barium are less available. Strontium is found in marine aquatic life, like hard corals. Barium is used in some imaging studies.

• Radium is highly radioactive metal and has a low availability. Exposure to radium can be dangerous to life.

Alkaline earth metal compounds:

 The alkaline earth metals react with other elements to form compounds that are used in several applications. For example
Alkyl magnesium halides are used to synthetize organic compounds. Calcium carbonate is used for making limestone, marble, and chalkin the construction industry.Magnesium oxide (MgO) is used in wire insulation and as a material to refract furnace brick.

Conclusion on alkaline earth metals:

The alkaline earth metals are a useful group of metals. There are differences in physical properties among these metals. A detailed study of these metals gives new insights into the behaviour of these metals and the chemical differences between them.

Alkanes physical and chemical properties

Introduction :   
Hydrogen atoms in a hydrocarbon aliphatic are perfumed by halogen atoms' consequences in the configuration of alkyl halide and aryl halide correspondingly. Haloalkanes have halogen atoms attached to the SP³ hybridised carbon atoms of an aryl group. Several halogens have organic composite which occur in nature and several of these are clinically useful. These classes of compounds locate wide applications in industry as well as in day-to day life.

Physical properties:

Physical properties:
Alkyl halides will be colourless while pure. Though bromides and iodides expand colour when exposed to light,several volatile halogen compounds contain sweet smell.

Melting and boiling points in physical properties:
Methyl chloride, methyl bromide, ethyl chloride also several chlorofluoromethanes are gas by room temperature. Higher members are liquids or solid. Since, we learnt that the contain, molecules of organic halogen mix are usually polar, suitable to greater polarity as well as higher molecular mass like evaluating to the parent hydrocarbon, the inter molecular forces of attraction are stronger in their halogen derived. The attractions get stronger as the molecules get bigger in size containing  more electrons.

Density in physical properties:
Bromo, iodo and polychloro derived of hydrocarbons are heavier than water. Physical properties of density increases among increase in number of carbon atoms. Halogen atoms with atomic mass of the halogen atoms.

Chemical properties:
Chemical Reactions of alkanes:
The chemical reactions of alkanes may be divided into the following categories:

• Nucleophilic substitution
• Elimination reactions
• Reaction with metals

Nucleophilic substitution in chemical reactions:
A nucleophile reacts with alkane having a partial positive charge on the carbon atom bonded to halogen. A substitution reaction obtain position with halogen atom known leaving group departs as halide ion.

Elimination reactions in chemical reactions:
When an alkane with B-hydrogen atom is heated among alcohilic solution of potassium hydroxide, here is removal of hydrogen atom from B-carbon and a halogen atom from the a-carbon atom.
Alkane is produced the product B-hydrogen atom is occupied in elimination, it is often known B-elimination.

Relation with metals in chemical reactions:
Mainly organic chlorides, bromides and iodides react with definite metals to provide compounds containing carbon-metal bonds. Such compounds are known as organo-metalli compounds.

Radio wave propagation

Introduction :
A radio wave is an electromagnetic wave whose frequency is lower than 3000 GHz, a wavelength greater than 0.1 mm.

The field of radio is regulated by the International Telecommunication Union (ITU) has established rules of radio communications in which one can read the following definition:

Radio waves or radio waves "electromagnetic waves with frequencies arbitrarily lower than 3000 GHz propagated in space without artificial guide" can be between 9 kHz and 3000 GHz which corresponds to wavelengths 33 km to 0.1 mm.

The wave frequency below 9 kHz radio waves are, however are not regulated.

The radio waves  are electromagnetic waves which propagate in two ways:
  * In the free space propagation (radiated around the Earth for example)
  * In lines (guided propagation in a coaxial cable or waveguide)

The field frequency radio waves ranges from 9 kHz to 3000 GHz.

Radio or electromagnetic wave in space :

The waves caused by a falling rock on the surface of a pond spread like concentric circles. The radio waves emitted by the isotropic antenna (that is to say, radiating uniformly in all directions in space) can be represented by a series of concentric spheres. One can imagine a balloon inflating fast, the speed of light c, very close to 300,000 km / s. After one second, the sphere has 600,000 km in diameter. If the propagation medium is not isotropic and homogeneous, the wave front will not be a sphere. As the radio wave is a vibration, after a period, the wave has traveled a distance denoted lambda and called wavelength. The wavelength is a key feature in the study of the spread, for a given frequency, it depends on the speed of wave propagation.

Radio Wave propagation in a line:

A generator connected to a load with a line will cause each of the two conductors of the line to establish an electric current and the formation of a wave moving in the dielectric at high speeds. This speed is less than the speed of light but frequently exceeds 200 000 km / s, which implies that for a given frequency, the wavelength in the line is smaller than in space.

In a coaxial line, the propagation speed is the same regardless of frequency, we say that the line is dispersive.

Propagation of electromagnetic waves

Propagation of Waves

 The process of communication involves the transmission of information from one location to another.  As we have seen, modulation is used to encode the information onto a carrier wave, and may involve analog or digital methods. It is only the characteristics of the carrier wave which determine how the signal will propagate over any significant distance.  This chapter describes the different ways that electromagnetic waves propagate.

Basics

An electromagnetic wave is created by a local disturbance in the electric and magnetic fields.  From its origin, the wave will propagate outwards in all directions.

If the medium in which it is propagating (air for example) is the same everywhere, the wave will spread out uniformly in all directions.

Far from its origin, it will have spread out enough that it will appear have the same amplitude everywhere on the plane perpendicular to its direction of travel (in the near vicinity of the observer). This type of wave is called a plane wave. A plane wave is an idealization that allows one to think of the entire wave traveling in a single direction, instead of spreading out in all directions.

Electromagnetic Wave Propagation at the speed of light in a vacuum. In other mediums, like air or glass, the speed of propagation is slower. If the speed of light in a vacuum is given the symbol c0, and the speed in some a medium is c, we can define the index of refraction, n as: 
Refraction

When the wave enters the new medium, the speed of propagation will change. In order to match the incident and transmitted wave at the boundary, the transmitted wave will change its direction of propagation.  For example, if the new medium has a higher index of refraction, which means the speed of propagation is lower, the wavelength will become shorter (frequency must stay the same because of the boundary conditions).  For the transmitted wave to match the incident wave at the boundary, the direction of propagation of the transmitted wave must be closer to perpendicular.

The relationship between the angles and indices of refraction is given by Snell's Law:
ni sinI = nt sint

Alkane nomenclature practice

Introduction :
Alkanes are the saturated hydrocarbons consisting elements of carbon (C) and hydrogen (H) in which atoms are linked together by single bonds. Alkanes are the member of a homologous series of organic compounds, where all members differ by a constant relative molecular mass of 14.

Each carbon atom have 4 single bonds (either C-H or C-C bonds), and each hydrogen atoms are joined to a carbon atom. A series of linked carbon atoms is known as the carbon skeleton or carbon backbone...The first member of alkane is methane, CH₄.

Structure and Isomerism of Alkanes:

Saturated hydrocarbons, Alkanes, may occur in linear, branched or cyclic forms. Alkanes having linear structure must have n<3.In this all the carbon  are attached  in a snake-like structure and alkanes having branched structure must have n>3. Alkanes having cyclic structure must have n>2.Alkanes having more than three carbon atoms are arranged in number of ways, so they form different structural isomers.

• First three members i.e. methane, ethane, and propane have one isomer.  
• Butane ,C₄H₁₀ has 2 isomers. they are n-butane, isobutene
• Pentane ,C₅H₁₂  has 3 isomers. They are pentane, isopentane, neopentane 
• Hexane, C₆H₁₄ has five  isomers
• Branched alkanes are chiral, e.g., 3-methylhexane and its higher homologues

Alkane nomenclature practice

• The number of carbon atoms can be indicated by ‘meth’ for one carbon atom, ‘eth’ for two , ‘prop’ for three, ‘but’ for four , ‘pent’ for five and so on…..

• Alkanes or saturated carbon atoms can be named by adding ‘ane’ suffix to the number of carbon atoms’ name. e.g., CH₄ can be named as methane. C₂H₆ can be named as ethane .First three members of alkanes form linear structure, so they have one isomer each.  

    Butane has two isomers. It can be named by using following rules:

• For naming branched chain isomers, firstly number of carbon atoms in series are counted and named according to it.

• Then number of methyl group is counted and also its position is located.

As per the IUPAC convention, we have certain rules to follow:

• First we have to find and then name the longest chain of carbon.
• Next we have to identify the groups which is being attached to the chain, after that we name it.
• Number the C- atoms in a chain that starts from the nearest substituent group.
• Assign the position of each group by a proper number and then we name it.
• Write the name of the listing groups which should be in an alphabetical order.
• di, tri, tetra, are used as prefix to assign several groups of similar kind. Alphabetizing is not taken into account.

E.g.  
1. C₄H₁₀           `->`     common name – n-butane      IUPAC name- butane 

 

2.

 

IUPAC names of the above alkane is 2- methylpropane

3.

IUPAC name of the above alkane is 2-methylbutane

4.

IUPAC name of the above alkane is 2,2-dimethylpropane

Conclusion for the nomenclature of alkane

From the discussion, we conclude that, in alkane each carbon atom have 4 single bonds and each hydrogen atom must be joined to a carbon atom .There is single bond between each carbon atom. They are saturated hydrocarbons.

Nomenclature of coordination compounds

Define nomenclature:
Nomenclature is significant in the coordination of chemistry because of the need to have an unambiguous method of describing formula and writing systematic names, particularly when dealing with isomer. The formulas and names adopted for ordination entities are based on the recommendation of the international union of pure and applied chemistry. A complex is an essence in which a metal atom or ion is linked with a collection of neutral molecules or anions call ligands.

Formulas of mononuclear coordination entities:

The formula of a compounds is shorthand tools used to provide basic information about the constitution of the compounds in the concise and convenient manner. Mononuclear synchronization entities include a particular central metal atom. Nomenclature coordination compounds are neutral substances in which at smallest amount one ion is absent as a complex.

• The central atoms is listed first
• The ligands are then listed in alphabetic order.
• Polydentate ligands are also scheduled alphabetically.
• The method for the complete coordination unit, whether charged or not is together with this in square brackets.
• There should be no space between the ligands and metal within the coordination.

Naming of mononuclear coordination compounds:

• The names of nomenclature coordination compounds are derivative by subsequent the principle of additive nomenclature. Thus the groups that surround the central atoms must be identified in the name.
• The cation is named primary in together positively and negatively charged coordination entity.
• The ligands are name in an alphabetical organize prior to the name of the central atom/ion.
• Names of the anionic ligands end in –o those of neutral and cationic ligands are the same except aqua for H₂O, ammine for NH₃, carbonyl for CO and Nitrosyl for NO. These are placed within enclosed marker ().
• When the name of the ligands include a numerical prefix, then the terms, bis, tris, tetrakis are used, the ligands to which they refer being placed in dichlorobis.
• Oxidation state of the metal in cation, anion or neutral coordination entities is indicating by Roman numeral in parenthesis
• If the complex ion is a cation, the metal is named same as the element. The neutral complex is named similar to that of the complex cation.

Making molar solutions

Introduction :
The amount of substance present in unit amount of the solution is called concentration of the solution.  Generally, concentration of a solution is expressed in
(a) molarity, M     (b) molality, m  or    (c) normality, N
Molarity:
“The number of gram molecular weight of the solute present in 1000 cm³ (or 1 dm³) of the solution is called molarity”.  It is denoted by the symbol M.

Making molar solutions Case1 and 2

Case 1:
Suppose 1 mole of Oxalic acid crystals (H₂C₂O₄. 2H₂O, Molecular weight 126g) is dissolved in 1dm³ of the solution. Molarity of the solution is 1.
Molarity of the solutions can be calculated from the expression
Formula for Molarity = (mass/dm³) / molecular weight
Case 2:
Suppose ‘x’ molar solution of Oxalic acid is asked to prepare.  Then, the weight of the Oxalic acid corresponding to ‘x’ mole of Oxalic acid is used in making x molar solution.
That is weight of Oxalic acid required is = ‘x’ moles X molecular weight of Oxalic acid
                                                                        = molarity X 126g
This much of Oxalic acid should be dissolved in 1 dm³ of solvent.

Making molar solutions Case3 ,4 and relation between molarity & normality

Case 3:
For the making of  ‘x’ molar solutions of Oxalic acid of a volume, say 100ml, the weight of the oxalic acid required is found using the below relation.

Case 4:

If a liquid reagent of certain % assay and density is given in the making of certain molar solutions, then the strength of the given liquid reagent should be determined first.  This is done by using the relation.

Strength = number of moles / dm³
               = (weight in g / Molecular weight) / dm³
               = density / Molecular weight
Now, the strength of the liquid reagent given is used in the making of the solution of required strength and volume using the below relation.
M₁.V₁ = M₂ V₂
Where:
M₁, M₂ are the molarities of the given liquid reagent and solution to be prepared
V_1, V₂ are the volumes of the given liquid reagent and solution to be prepared, respectively.
Since, Equivalent weight and Molecular weight are related as:

So, there exists a relation between the molarity and normality as below:
Molarity = (mass/dm³) / Mol. Wt
               = (mass/dm³) / [Eq. wt x valence (number of electron exchange)]
Molarity = Normality / valence    or
Normality = Molarity X valence         is used in the making of N solutions from M solutions.

Mass and volume relationship

Introduction 
Mass is the measure of inertia.  Mass of an atom is composed of the mass of the protons and the mass of the neutrons.  The mass of the electrons is negligible. It is the same thing with molecules.   The mass of a particular compound is the mass of its molecules.

 Similarly, volume is also a property exhibited by any gas. It is the space occupied by a gas.  Each gas at a certain temperature has a specific volume depending upon its mass. There is a certain co-relationship between mass and the volume of the gas at a particular temperature.

Mass and molar mass definition :

In chemistry, the mass is often expressed in terms of molar mass. The molar mass is the mass of one mole of a gas.  One mole of a gas is nothing but gram equivalent of the gas.
 To illustrate, take the gas, carbon monoxide, the molar mass of carbon monoxide is 12+ 16 = 28. 

When this mass which is in atomic mass unit is expressed in grams instead of atomic mass unit it is called as one mole. 

So one mole of carbon dioxide is 28 grams. And it has been proved that there is definite relationship between the volume and molar mass of the gas.

The relationship between the molar mass and the volume is that 1 mole of the gas would occupy 22.4 liters of volume. 

In the above case where the molar mass of carbon dioxide is 28, 28 grams of carbon dioxide would occupy 22.4 liters of volume.  This relationship was developed from the equation of ideal gas i.e. PV = nRT, where 'n' is number of moles. 

At standard temperature and pressure the values of which are 273° kelvin and 1 atmosphere, the volume figure derived is 22.4 liters. 

If the mass of a gas is expressed as 'z' then it can be said that 'z' grams of a gas occupy (z/molar mass x 22.4) liters of volume.

Illustration of mass and volume relationship

Find the volume occupied by 56 grams of carbon dioxide.
The molar mass of carbon dioxide is 28;
hence number of moles = 56 / 28 = 2 moles.
 Since one mole occupies 22.4 liters at STP,
2 moles of carbon dioxide would occupy 44.8 liters of volume.

Amplitude Modulation Side Band

Introduction :-

Modulation is the process of changing one or more properties like amplitude, frequency, phase of high frequency carrier wave in accordance with the Modulating wave. Here the Modulating wave is base-band signal. Example of base-band signal is speech or music signal.

what is amplitude modulation : Amplitude Modulation is the process of changing Amplitude of high frequency carrier wave in accordance with the Amplitude of Modulating wave.

Definition of Side-Band:

A group of frequencies which is having frequency fc±fm is called as Side-Band. Here fc=Carrier frequency and fm=modulating frequency. fc+fm is called as upper side-band and fc-fm is called as lower side-band.

Different types of Amplitude Modulation

Depending on side-bands we have 5 different types of Amplitude Modulation.

1. Double-Sideband Full Carrier

2. Single-Sideband Full Carrier

3. Single-Sideband Reduced Carrier

4. Vestigial-Sideband

1. Double-Sideband Full Carrier:

The technique of amplitude modulation in which along with the carrier if both upper side-band and lower side-band is transmitted then that amplitude modulation is called as Double-Sideband full carrier.

In order to increase the efficiency of transmitter we may suppress the carrier from this DSB-AM then that technique is called as Double-Sideband Suppressed carrier Amplitude Modulation Method.

This type of amplitude Modulation is also called as conventional amplitude modulation

2. Single-Sideband Full carrier:

The technique of amplitude modulation in which single side-band is transmitted is called as single-sideband Full carrier and is denoted as SSB.

This type of modulation technique is used in shortwave radio or shortwave broadcasting

3. Single-Sideband Reduced Carrier:

The technique of amplitude modulation in which carrier and single side band is suppressed then that type of amplitude modulation is called as single-sideband Reduced carrier.

This type of modulation technique is used in amateur radio.

4. Vestigial-Sideband:

The technique of amplitude modulation in which part of single side band and all other remain as it is ,then that type of amplitude modulation in called as vestigial side-band.

This type of modulating technique is used in transmission of Television i.e., Television broadcasting.

kinetic energy of a particle

In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working" is a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. Different forms of energy include kinetic, potential, thermal, gravitational, sound, elastic, light, and electromagnetic energy. The forms of energy are often named after a related force. German physicist Hermann von Helmholtz established that all forms of energy are equivalent - energy in one form can disappear but the same amount of energy will appear in another form. Energy is subject to a conservation law. Energy is a scalar physical quantity. In the International System of Units (SI), energy is measured in joules, but in some fields other units such as kilowatt-hours and kilocalories are also used.

Any form of energy can be transformed into another form. When energy is in a form other than heat, it may be transformed with good or even perfect efficiency, to any other type of energy. With thermal energy, however, there are often limits to the efficiency of the conversion to other forms of energy, due to the second law of thermodynamics. As an example, oil is reacted with oxygen, potential energy is released, since new chemical bonds are formed in the products which are more powerful than those in the oil and oxygen.

The released energy resulting from this process may be converted directly to electricity (as in a fuel cell) with good efficiency. Alternately it may be converted into thermal energy, if the oil is simply burned in order to heat the combustion gases to a certain temperature. In the latter case, however, some of the thermal energy can no longer be used to perform work at that temperature, and is said to be "degraded." As such, it exists in a form unavailable for further transformation. The remainder of the heat may be used to produce any other type of energy, such as electricity.

In all such energy transformation processes, the total energy remains the same. Energy may not be created nor destroyed. This principle, the conservation of energy equation, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy (and higher total energy) relative to the Earth.

Kinetic Energy of Gasses

Introduction :
Let us see about the kinetic energy of gases. In continuous motion, molecules also exert strong electric forces on one another when they are close together. The forces are both attractive and repulsive. The former hold molecules together and the latter cause matter to resist compression. The kinetic theory can explain the existence of the solid, liquid and gaseous states.

Two ways of measuring kinetic Energy:

The energy produced by a body by virtue of its motion is called kinetic energy. A moving body gives kinetic energy. For example bullet shot forms a rifle, flossing water of a river, blowing wind have kinetic energy. A moving body can do work due to its kinetic energy. For example the kinetic energy of a hammer is used to drive a nail in wooden block; the kinetic energy of air may be used to run wind mills, the kinetic energy of a bullet fired from a gun can pierce a target.
The kinetic energy of a body may be measure in two ways.

• By calculating the work required by an external agent to set the body into motion from the state or rest.
• By calculating the work done by the moving body against dissipative force before it comes to rest.

Kinetic Energy of Gases:

The molecules in gases are much farther apart than in solids or liquids and so gases are much less dense and can be squeezed into a smaller space. The molecules dash around at very high speed about 500m/s in all the space available. It is only during the brief spells when they collide with other molecules or with the walls of the container that the molecular forces act.

A model of a gas is shown in figure. The faster the vibrator works the more often the ball-bearings have collisions with the lid, the tube and with each other, representing a gas at a higher temperature. Adding more ball-bearing is like pumping more air into a tyre. If a polystyrene ball is dropped into the tube its irregular motion represents Brownian motion.

Benzene molecular formula

Introduction :
Carbon has valency of 4.Hydrogen has valency of 1.Untill the discovery of benzene,no compound with find empirical formula C_nH_n was discovered.As such benzene with same empirical formula posed a great challenge.It was predicted that the molecule would invariably contain unsaturation.

Progressive attempts on benzene molecular formula

Since it was first isolated and identified in 1825,the knowledge of structure of eluded the chemists for many decades

The existence of double bond in ethene was discovered by Scottish chemist Alexander Brown in 1864.However the discovery of the probable structure of C6H6 continued to dodge the chemists.It was so because never before was any structure derived for a compound with the empirical  formula C_nH_n.
The chemists were confused as to how all the valencies of carbon would stand satisfied in such a compound.

Kekule's contribution in benzene molecular formula

Simultaneously attempts were also made by Adolph Carl Ludwig Clause ,Henry Armstrong etc. to propose certain structures.However they failed.

It was only in 1865 that Kekule could make a breakthrough in devising this structure.He devised the structure with hexagonal ring. He said that he had discovered the ring shape of the benzene molecule after having  day-dream of a snake seizing its own tail .

This structure  met with lot of criticism in the beginning and was further refined.In 1872 he put forth that the atoms are oscillating and were in reverse and forward collision with the neighbouring carbon atoms.

pi bonds in benzene

Kekule put forth the correct structure in 1865.According to it ,benzene has aromatic structure. He revealed that he had discovered the ring shape of the benzene molecule after having  day-dream of a snake seizing its own tail .This structure  met with lot of criticism in the beginning and was further refined.
The only way in which this could be explained is pi bonds in the aromatic ring.

Unconventional pi bonds

It means it consists of a conjugated planar ring system with delocalized pi electron clouds.These electtrons which form the double pi bond keep on 'hopping' between subsequent bonds.This also can be expressed in following sentence.

The electrons for C–C bonding are distributed equally between each of the six carbon atoms.
Average length between the C-C and C=C is at 0.139 nm. This is called as 'resonance'. Resonance adds to the energy of the structure. As a result benzene is more stable by 150 kJ mol^-1than predicted by Kekule because of resonance.

Each carbon atom is attached to one hydrogen atom in addition to two carbon atoms.The electrons of the pi bonds keep on oscillating forth and back.In this way an the valencies of the atoms stand satisfied,albeit in a unconventional way.Thus in order to facilitate this,the structure would be planar and not three dimensional.This enhanced stability is the fundamental property of aromatic molecules that differentiates them from non-aromatic molecules.

Because of these pi bonds, benzene undergoes nucleophilic as well as electrophilic addition reactions at one end of any double bond.

Structure with respect to moleculr formula

The structure of benzene has aromatic nature.
It means it consists of a conjugated planar ring system with delocalized pi electron clouds.The electrons for C–C bonding are distributed equally between each of the six carbon atoms. Each carbon atom is attached to one hydrogen atom.The electrons of the pi bonds keep on oscillating forth and back.In this way an the valencies of the atoms stand satisfied,albeit in a unconventional way.Thus in order to facilitate this,the structure would be planar and not three dimensional.This enhanced stability is the fundamental property of aromatic molecules that differentiates them from non-aromatic molecules .

The discovery of ring structure of benzene has led to vast field of aromatic compounds in organic chemistry. Many important chemicals are derived from benzene by replacing one or more of its hydrogen atoms with another functional groups.e.g toluene,phenol etc.The ring structure is also the basic unit of many biochemicals like hormones.

Atomic structure of phosphorus

Introduction
Phosphorus is an element of Group 15 and period 3. Its symbol is P having atomic number 15 and mass number 31. It belongs to p- block elements. It is a non- metal. Its electronic configuration is
[Ne]3S² 3P³

It generally exists in two forms, white phosphorus and red phosphorus. It is very reactive so it is not found in Free State in nature. White phosphorus emits light or glows when exposed to air or oxygen.

Atomic structure of phosphorus

Atomic number of phosphorus is 15 and thus its electronic configuration is 2,8,5. So it has following atomic structure.It has 2 electrons in K shell, 8 in L and 5 in M shell.

Image of phosphorus and its structure

Properties of phosphorus

Luminsecence is the main property of phosphorus. This property can be defined as the ability to emit light or glow in dark. Allotropes.

Phosphorus has two common allotropes called white phosphorus and red phosphorus. Red phosphorus is an intermediate phase between white and violet phosphorus. White phosphorus is most reactive and least stable form of all allotropes of phosphorus. It is insoluble in water. Two radioactive isotopes of phosphorus have half-lives that make them useful for scientific experiments. ³²P has a half-life of 14.262 days and ³³P has a half-life of 25.34 days. Phosphorus can expand its valence electron to make penta- and hexavalent compounds eg phosphorus chloride molecule.

Most common Oxidation states of Phosphorus are 5, 4, 3, 2, 1 , -1, -2, -3

The first, second and third Ionization energies of phosphorus are as follows
1011.8 kJ·mol⁻¹, 1907 kJ·mol⁻¹ and 2914.1 kJ·mol⁻¹.As per Pauling scale the Electronegativity of phosphorus is 2.19.

Preparation of phosphorus by Brand’s process

Phosphorus is not found in the native state in nature as it is reactive. So it can be prepared by Brand's process by using sand in the reaction

4 NaPO₃ + 2 SiO₂ + 10 C → 2 Na₂SiO₃ + 10 CO + P₄

Phosphate rock is the main source of phosphorus. It is made up of tri-calcium phosphate mineral called apatite.

Conclusion for the atomic structure of phosphorus

From the discussion, we conclude that phosphorus is a non metal having atomic number 15 and is reactive. It has 5 valence electrons in its outermost shell so it needs 3 more electrons to complete the octet. So it is reactive.

Atomic structure of Nickel

Introduction :
Nickel was accidentally discovered by Axel F Cronstendt when he was trying to isolate the element from its mineral ore kupfernickel in Sweden taking it to be copper. Nickel is mostly available in the pentlandite [(Ni, Fe)9S8] and garnierite ores found in countries like South Africa, Russia, Australia and Canada. It was discovered 250 years ago. It is the fifth most abundant element on earth.

Structure for Atomic structure of Nickel

Nickel is a group 10 element and is one of the transition elements holding an atomic number of 28. With an atomic number 28, nickel has 28 electrons in various energy levels or these electrons are distributed in the orbitals of the atom.

As the atomic number of nickel is 28 it has 28 protons and 28 electrons. It has 31 neutrons in the atom's nucleus. The electrons assigned to different orbitals are 2, 8,16,2. The electron configuration of nickel can be written as 1s2 2s2p6 3s2p6d8 4s2 . The only Ferro-magnetic elements are nickel, iron & cobalt and among them nickel is supposed to be least magnetic.

Atomic structure of Nickel – properties and uses

Properties:

Nickel is corrosion resistant but it is soluble in acids. Alkalis do not affect Nickel though. 58.6934is the atomic mass of nickel. 2732 degree Celsius is its boiling point. 1453 degree Celsius is its melting point. 6.59 cm³/mole is its molar volume. Its density is 8.9g/cc.

Uses of Nickel:

Electroplating and for formation of metal alloys nickel is used because of its resistance to corrosion. It is also used as catalyst in nickel-cadmium batteries. It is also the main constituent in coins. Because of durability, strength and corrosion resistance nickel alloys are the most sought after compared to other alloys. In animals, nickel along with iron plays an important role of transporting oxygen in blood. It is part of enzyme functioning in plants & animals. Whole grains such as oats are excellent source of nickel. It is also part of genetic code DNA & RNA. In many cordless appliances, nickel-cadmium batteries are commonly used.

Conclusion for Atomic structure of Nickel

As per the discussion on atomic structure of nickel, we came to know that, other metals can be used in place of nickel and one more reason is its cost effectiveness, nickel is the most preferred metal.

Magnesium atomic weight

Introduction :
Atomic weight is the mass of an atom expressed in Atomic Mass Units (amu). An atomic mass unit is equal to one-twelfth of the mass of a carbon atom of the isotope C-12.

An atom consists of subatomic particles electrons, protons, and neutrons. Protons and neutrons have equal mass of 1 amu, whereas electrons have negligible mass. So for the atomic weight of an element, we do not consider the mass of electrons.

Atomic weight = Number of nucleons.
'Nucleons' is the term for protons and neutrons.
Atomic weight is represented by the letter 'Z'.

Thus, if there are 7 protons and 7 neutrons in the nucleus of an atom, then its atomic weight will be
Z = 14 amu.

Atomic weight of magnessium:

Electronic configuration
The magnesium atom has 12 protons and 12 neutrons in its nucleus. Therefore magnesium atomic weight is Z = 24 amu. The following diagram shows a magnesium atom. It's nucleus contains 12 protons and neutrons and it is surrounded by 3 orbits having 2, 8 and 2 electrons respectively.

Position in periodic table
Magnesium is located in the 3^rd period of the periodic table. It is the second element of group 2 of the periodic table.

Reactivity
Magnesium is a highly inflammable metal. To stop a “magnesium-fire”, the only option is to put sand on the burning magnesium so as to avoid its contact with the atmosphere. Magnesium owes this behavior to the fact that it burns in oxygen, nitrogen, carbon dioxide as well as water vapor also.

Magnesium has a valency of 2. It loses two electrons to form positive ions during its chemical reactions. Thus, the majority of chemical reactions undergone by magnesium are ionic in nature, and it mostly forms ionic compounds. It reacts slowly with water at room temperature, releasing Hydrogen gas bubbles. It also reacts with most acids in an exothermic reaction.

Other properties
Most magnesium compounds are white in color and soluble in water, giving it a slightly sour taste due to Mg2+ ions. The commercially important Magnesium minerals are dolomite, magnesite, brucite, carnallite, talc, and olivine. Magnesium is present in ocean water as salts of its compounds, and this way it is the second most abundant metal present in ocean water. Also, Magnesium is the seventh most abundant element in the earth's crust.

Magnesium properties and uses

Physical properties

• Magnesium is a silvery white metal. It is strong, light-weight and ideal for making machines. Since magnesium cannot react with atmospheric oxygen on exposure to air, it is used as alloy in building machines and structures.
• Magnesium also has a high tensile strength and thus it is ideal to use in building structures.
• Magnesium is ductile, and can be cut very easily. On the other hand, its resistance to deformation is higher than most other metals. Furthermore, it is not brittle to impact, and thus, it is highly siutable fot construction of lagre buidings and structures.
• Magnesium has a high shock absorbing capacity, and is a good conductor of heat. It is resistive to time and temperature and can be cut, welded, molded very easily. Thus, it is an ideal metal for machine making also.
• Magnesium compounds when dissolved in water taste sour due to the presence of magnesium ions (Mg2+)

Chemical properties

• It is reactive to air, and tarnishes in the presence of atmospheric oxygen. However, on reaction with air, it forms a protective covering of magnesium oxide on its surface, which prevents further reactions of the metal. Thus, magnesium can be stored in normal environment. Formation of oxide: `Mg + O2 -gt 2MgO`
• Magnesium reacts with water at room temperature, though the reaction stops after a short time because of the formation of the insoluble Magnesium Hydroxide. Reaction: `Mg + H2O -gt Mg(OH)2 + H2`
• Magnesium burns in steam to form its oxide and Hydrogen gas. Reaction: `MG + H2O (steam) -gt MgO + H2`
• Magnesium also reacts with acids like Hydrochloric acid to produce its Chloride, liberate Hydrogen and heat (it is an exothermic reaction). Reaction: `Mg + 2HCl -gt MgCl2 + H2`
• Magnesium burns in air with a brilliant white light. It is reactive with Oxygen, Nitrogen, Carbon dioxide and also water vaopour in air, and thus it is difficult to distingiush a magnesium fire. Reaction of Magnesium with oxygen and nitrogen: `2Mg + O2 -gt2MgO`
        `3Mg + N2 -gt Mg3N2`
  

Uses

• It is used in the manufacture of automobile and truck components.
• It is widely used in making race cars, since it is a light, resistant metal.
• It is also widely used in the manufacturing of electronic devices like cell phones, laptops, etc.
• Magnesium was widely used in the construction of air crafts.
• Used in incendiary weapons in firebombin of cities in WWII
• Milk of magnesia is sometimes used as an antacid, as it is a mild base.
• Magnesium is used in photography to produce flares of brilliant white light, and is also used in fireworks for sparklers.

Atomic number 93

Introduction 

• From periodic table Atomic number 93 is ‘Neptunium’.
• Chemical symbol is ‘Np’.
• Neptunium as atomic number is 93 and mass number is 237.0482
• Neptunium belongs to f-block element because the atom has valence electron in f-orbital.
• f-block elements are also called inner transition elements.
• In Neptunium the outermost electrons are in 5f-orbitals
• Neptunium atom belongs to actinide series. 
• It has electronic configuration [Rn], 7s², 6d¹, 5f²
• It occurs in solid state in nature.
• Atomic number 93 was discovered by Edwin Mcmillan and Philip H.  Abelson in the year 1940 in Berkeley, California.
• Trace amount of Neptunium are naturally found as a decay product from transmutation reaction in uranium ores.

 Sources of Neptunium
Np is most often extracted from spent nuclear fuel rods as a by-product of plutonium production.
Artificial ²³⁷Np is produced through the reduction of ²³⁷NpF₃ with barium or lithium vapour at 1200⁰C.
     2NpF₃    +    3Ba    →    2Np    +    3BaF₂
When uranium atom is bombarded with slow moving neutron, ²³⁹Np was produced.  It was first transuranium element.  At the time 23 minute.  Elimination of β^- particle occurs, Neptunium is obtained.
      ₉₂U²³⁸ + ₀n¹  →  ₉₂U²³⁹  →  ₉₃Np²³⁹

Properties of Atomic number 93

• Neptunium element has density 20.45g/cm³.
• It has melting point 910K and high boiling point of 4273K.
• It has oxidation state 7, 6, 5, 4, 3.
• Atomic number 93 has atomic radius 155pm.
• Neptunium has three crystal structure forms.

Half life of Np

There are nineteen  neptunium radioisotopes which have been characterized, with the most stable being ²³⁷Np with a half-life of 2.14 million years, ²³⁶Np with a half-life of 154,000 years, and ²³⁵Np with a half-life of 396.1 days. All of the remaining radioactiveMeta states, with the most stable being ²³⁶Np which as half life of 22.5 hours. isotopes have half-lives which have less than 4.5 days, and the majority of these have half-lives that are less than 50 minutes. This element also has 4

Synthesis of Atomic number 93
When a ²³⁵U atom captures a neutron, it is converted to an excited state of ²³⁶U. About 81% of the excited ²³⁶U nuclei undergo fission, but the remainder decay to the ground state of ²³⁶U by emitting gamma radiation. Further neutron capture creates ²³⁷U which has a half-life of 7 days and thus quickly decays to ²³⁷Np through beta decay. During beta decay, the excited ²³⁷U emits an electron, while the atomic weak interaction converts a neutron to a proton, thus creating ²³⁷Np.
    ₉₂U^{235 +} ₀n¹    → ₉₂Um²³⁶    →  ₉₂U²³⁶  + γ
    ₉₂U²³⁶  +  ₀n¹    →  ₉₂U²³⁷      →  ₉₃Np²³⁷

Uses of Atomic number 93

• ²³⁷Np is irradiated with neutrons to create ²³⁸Pu, an alpha emitter for radioisotope thermal generators for spacecraft and military applications. ²³⁷Np will capture a neutron to form ²³⁸Np and beta decay with a half life of two days to produce ²³⁸Pu.

      ₉₃Np²³⁷ + ₀n¹ → ₉₃Np²³⁸  →  ₉₄Pu²³⁸

• Np is fissionable, and could be theoretically be used as fuel in a fast neutron reactor or nuclear weapon.
• ²³⁷Np is used in devices for detecting high-energy (MeV) neutrons.