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.