Periodic table alkali metals

Introduction :   

Elements belonging to group 1in periodic table are called alkali metals.  Their outer most electronic configuration is ns1 in periodic table.

Z        Element        No. of electrons

1         Hydrogen             1

3         Lithium                2, 1

11       Sodium               2, 8, 1

19       Potassium           2, 8, 8, 1

37       Rubidium            2, 8, 18, 8, 1

55      Caesium              2, 8, 18, 18, 8, 1

87      Francium             2, 8, 18, 32, 18, 8, 1

The group in a periodic table also includes hydrogen because of the similarity in the electronic configuration with these elements.  They are called alkali metals since they readily dissolve in water to form soluble hydroxides which are strongly alkaline in nature.  The word alkali has been derived from the Arabic word alquili, which means the ashes of plants from which certain compound of the elements sodium and potassium were initially isolated.  Sodium and potassium are abundant while the remaining elements occur only in traces.  The last element francium is radioactive and unstable. 

Alkali metals of periodic table:

They have maximum value of atomic radii, form monovalent  cations and possess the lowest ionization enthalpies  Their hydration enthalpies are low due to their large size. They have low electro negativities and all the members are strongly electro positive.They possess +1 oxidation state, and have low melting and boiling points. They are very light and impart characteristic colors to the flame.They exhibit photoelectric effect. 

They are highly reactive chemically because of their low ionization enthalpies and enthalpy of atomization. They are normally kept in chemically inert solvents such as kerosene.  They form oxide when they combine with oxygen and hydroxide when they react with water.The reaction with water is highly exothermic.So, alkali metals are not kept in contact with water.All alkali metals combine with hydrogen upon heating to form colorless crystalline hydrides that are ionic in nature.They combine with halogens directly to form metal halides. The alkali metals are powerful reducing agents.They are soluble in liquefied ammonia.They react with sulphur and prosperous upon heating to form the corresponding sulphides and phosphides.  

Hydrogen atom consists

Introduction

A hydrogen atom consists of an atom of the chemical element hydrogen. It is an electrically neutral atom which contains a single positively-charged proton and a single negatively-charged electron and they are bound to the nucleus by the Coulomb force. Hydrogen-1, protium, or light hydrogen is the most abundant isotope and it contains no neutrons. There are other isotopes of hydrogen, such as deuterium which contains one or more neutrons.

Niels Bohr in the year 1914 got hold of the spectral frequencies of the hydrogen atom subsequent to making a number of straightforward assumptions. The assumptions were not fully right but they gave up the proper energy answers.

Schrödinger equation and Hydrogen atom

The confirmation of the Bohr's results for the frequencies and underlying energy values were done using Schrödinger equation between the years 1925-1926. The clarification to the Schrödinger equation for hydrogen is systematic. This equation can be used to find out energy levels and thus the hydrogen spectral lines frequencies can be measured. The explanation of the Schrödinger equation goes much advance than the Bohr model nevertheless, for the reason that it also gives way to the shape of the electron's wave function ("orbital") for the various possible quantum-mechanical states, thus clearing up the anisotropic character of atomic bonds. This equation for the hydrogen atom is based on the fact that the coloumb potential which is produced by the nucleus is isotropic in nature. It is radially symmetrical in space and depends on the distance to the nucleus. The resulting eigen energy functions are not isotropic themselves.

Hydrogen ion

In ordinary chemistry, hydrogen is not found without its electron at room temperatures and pressure. Ionized hydrogen is written as "H⁺". Ionized hydrogen in case of the salvation of classical acids like hydrochloric acids forms hydronium ion. Hydronium ion is written as H₃O⁺. This refers to the entire hydronium ion and to a single ionized hydrogen atom. In this type of case, the proton is transferred by acid from water to the hydronium ion. This type of ionized hydrogen without their electron or free protons is commonly observed in the solar wind and interstellar medium

The nucleus of an atom contains

An atom is constructed of three major particles; two of them are in a central region or core called the atomic nucleus. The third type of particle is in the region surrounding the nucleus. The weight or mass of the atom is concentrated in the nucleus. The nucleus of the atom contains the protons and the neutrons, which are the massive particles of the atom. One type of particle located in the nucleus is the neutron.

Introduction 

Neutrons were named to reflect their lack of electrical charge. They are neutral. Protons, the second type of particle in the nucleus in certain areas called  enegry levels are the electrons. Each electron has a negative electrical charge. The number of electrons determine the space that an atom occupies.

Charge of an atom

The charge of an atom is neutral if the number of positively charged protons equals the number of negatively charged electrons. For instance, hydrogen with 1 proton, would have 1 electron; carbon with 6 protons would have 6 electrons. You can determine the number of either of these two particles in a neutral atom if you know the number of other particles.

Identity of the element
All the atoms of the same element have the same number of protons. The number of protons determine the identity of the element. For example, carbon always has 6 protons and no other element has that number. Oxygen always has 8 protons. The atomic number of an element is the number of protons in an atom of that element; therefore, each element has a unique atomic number. Because this is an extremely small mass and is awkward to express, 1 proton is said to have a mass of 1 atomic mass unit.

Neutral atoms
Although all the neutral atoms of the same element have the same number of protons and electrons, they do not always have the same number of neutrons. In the case of oxygen, over 99% of the atoms have 8 neutrons, but there are others with more or fewer neutrons. Each atom of the same element with a different number of neutrons is called an isotope of that element. Since neutrons have a mass very similar to that of a proton, isotopes that have more neutrons will have a greater mass than those that have fewer neutrons.

Isotopes
Elements occur in nature as a mixture of isotopes. The atomic weight of an element is an average of all the isotopes present in their normal proportions. For example, of all the isotopes present in their normal proportions. For example, of all the hydrogen isotopes on Earth, 99.985% occur as an isotope without a neutron and 0.015% as the isotope with one neutron.There is a third isotope with two neutrons but it is not considered because it is highly unstable. When the math is done to account for the relative amounts of the various isotopes of hydrogen, the atomic weight turns out to be 1.0079 AMU.

Mass number of an atom
The sum of the number of protons and neutrons in the nucleus of an atom is called the mass number. Mass numbers are used to identify isotopes. A hydrogen atom with 1 proton and 1 neutron has a  mass number of 1 + 1, or 2, and is reffered to as hydrogen-2 ( also called deuterium). A hydrogen atom with 1 proton and 2 neutrons has a mass number of 1 + 2 , or 3, and is referred to as hydrogen-3 ( also called tritium).

3 particles of an atom

Hi There are 3 main particles of an atom. They are electrons, protons and neutrons.

Introduction to 3 particles of an atom

Protons
Protons are the most elementary particles of an atom.
They are situated in the nucleus.
They carry single positive charge.
In fact, charge carried by a proton has been labeled as single charge.
How do all the protons, which are similarly charged stay composed in the nucleus?
It is because of energy called binding energy.
The number at the base of an atom represent the atomic number.
e.g.In case of carbon ₆C, the atomic number is 6, which means number of protons is 6.

Neutrons

They are nuclear particles with mass nearby that of protons but no charge.
Since they are part of mass number along with the protons, the number of neutrons is equal to,
Mass number - Number of protons.
e.g: The mass number of Krypton is 84 and the number of protons is 36.
So the number of neutrons =  84 - 36 = 48
Mass number is written at the top of the symbol of the element.

Electrons

Electrons are negatively charged subatomic particles.

The charge is −1.602×10⁻¹⁹ Coulomb.
Their mass is 1/1836 ^th of that of proton and is many a times neglected in related calculations.
Electrons are rotating outside the nucleus of an atom. They are arranged in sub-shells in different energy levels.

The energy levels are named as K, L, M, N etc.., and the sub-shells as s, p, d, f etc.., Electrons posses a spin of +1/2 or -1/2.

Electrons are elementary particles and are not composed of quarks. They were discovered by J.J.Thompson in 1897.

Electricity is actually flow of electrons.
Chemical bonds are formed either by donating, accepting or sharing of electrons.
As the number of electrons is same as that of protons, the atom attains stability as the opposite charges attract one another.
Thus the number of electrons can be found from the number of protons.

Iron atom

Introduction 

Iron atom is a chemical element having atomic number 26 and with the symbol ‘Fe’ which in Latin means ferrum.  It is a metal in the first transition series.  Like other ‘group 8’ elements, it exists in several oxidation states. The oxidation states of iron is +2 and +3, it might also occur in higher oxidation states of about +6.  Iron (II) compounds are called ferric and iron(III) compounds are called ferrous.   Iron and its alloys are the widely used ferromagnetic materials in the modern day life.

Pure iron is softer than aluminum.  Steel can be prepared by alloying pure iron with small amounts of other metals and carbon. The alloy steel is almost 1,000 times harder than pure iron.  It is the most common element found on earth.  It reacts with air to form iron oxides also known as rust. The rusting of iron and its alloys is undesirable, and has a major economic impact. The melting point of iron is about 1535 °C. Its mechanical properties can be varied extensively by varying the carbon content in the alloy.

      Different types of Iron are

1.   Pig iron has 3.5–4.5% carbon
2.   Cast iron contains 2–4% carbon 
3.   Wrought iron has less than 0.008% carbon

Occurrence and Biological Importance of Iron atom

Occurrence of Iron atom: Iron is the fourth most abundant element in the Universe, formed from the process known as nucleosynthesis, by the fusion of silicon in huge stars. Metallic iron is rarely found on the surface of the earth because it tends to oxidize, but its oxides are diffused and represents the primary ores. About 5% of the earths curst constitutes of Iron.  Most of the Inner and outer core of earth consists of Iron-Nickel alloy which is about 35% of the total mass of the earth.  Hematite and Magnetite are the most common form of iron ore which is found in earth crust. These ores are combined with oxygen to form iron oxides. 

Biological importance of Iron atom: Iron plays a major role in biology.  Ranging from the primitive archaea to humans, all living organism has iron-proteins.  Hemoglobin is a protein containing iron.  Hemoglobin is responsible for the color of the blood.  Hemoglobin and myoglobin are the two compounds which helps in the transportation of oxygen proteins in vertebrates.  Iron is present in each and every cell of the human body. It is the basic necessity for the growth and development of a living organism.

Applications of Iron

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.