Introduction of Hydrogen and Hydrogen Properties, Hydrides

Basic properties of Hydrogen

Hydrogen has an atomic number of 1 as shown in the periodic table. The symbol of Hydrogen is H. The atomic weight of Hydrogen is 1.00794 and the melting point of Hydrogen is -255.34°C. Hydrogen has a boiling point of -252.87°C. Hydrogen is a colourless, odourless, tasteless gas. Hydrogen is the lightest element and simplest chemical element. Having an atomic number of 1, Hydrogen is the most abundant element in the universe.

Hydrogen is the atomic fuel devoured by the sun and different stars to create energy. Albeit, 70% of the universe is made out of hydrogen, hydrogen comprises just 0.87%  of the earth’s mass. The greater part of the hydrogen found on earth is related to Oxygen. Water, for instance, is 11% hydrogen by mass and is the most plentiful hydrogen compound. Hydrogen is likewise a significant piece of oil, cellulose, starch, fats, alcohols, acids, and a wide assortment of different materials.

Where does the name Hydrogen come from?

The name Hydrogen is taken from the Greek hydro + genes (gennao) meaning water generator.

Who discovered Hydrogen chemical element?

Hydrogen is isolated and identified as an element by an English chemist Henry Cavendish (1731-1810) in 1766. Henry Cavendish first isolated pure hydrogen and distinguished it from other gases. Because hydrogen produces water when burned in air, the French chemist Lavoisier gave hydrogen its name. Hydrogen means water producer.

Hydrogen Atom

The hydrogen atom is the simplest atom that can possibly exist. Its most common isotope is composed of a single proton and an electron. If you take away either of these parts, you no longer have an atom at all.

There is relatively little hydrogen gas in the earth’s atmosphere, but there are plenty of hydrogen atoms showing up in hydrogen compounds such as water, for instance.

Most abundant chemical element

Consider that every molecule of water in all the seas, lakes, and streams includes two hydrogen atoms. Hydrogen makes the list of the ten most abundant elements on the earth.

Uses of Hydrogen

Nearly two thirds of the hydrogen that is commercially produced today is used in the Haber process for manufacturing ammonia. The food industry also consumes a lot of hydrogen for hydrogenating simple vegetable oils. The end products including margarine, cooking oil, and salad dressings, are much healthier for you than their counterparts traditionally produced from animal fats. Finally, a small amount of elemental hydrogen is used in liquid form as a rocket fuel.

Hydrogen Properties

Hydrogen is chemically unique in a number of ways. Among these unique features is Hydrogen ‘s ability to form compounds by giving up an electron or acquiring one. Elements that give up electrons to form compounds are considered electropositive and appear at the left side of the periodic chart of the elements.

On the other hand, elements that gain electrons to form compounds are called electronegative elements, and appear near the righthand side of the periodic chart.

Unique property of Hydrogen

Hydrogen is the one and only element that can do both; Hydrogen can be placed in Group IA (electropositive) or Group VIIA (electronegative). No other element has an ambiguous position on the periodic chart. Most periodic charts show hydrogen in its IA position. A few show Hydrogen in the VIIA position as well.


Hydrogen tends to be diatomic. This means the molecules are composed of two atoms; therefore, the gas is represented symbolically as H2.

Two types of Hydrogen molecules

There are two types of H2 molecules, ortho-hydrogen and para-hydrogen.

  • In the ortho hydrogen molecule, the two protons spin in the same plane;
  • In the para-hydrogen molecule, the spins are in opposite planes.

This affects the magnetic properties and electronic band spectra of the molecules. In ordinary hydrogen gas and normal environmental temperatures, the ratio of ortho- to para-hydrogen is 3:1. The portions are roughly equivalent at – 200°C, and the amount of para-hydrogen approaches 100% as the temperature nears absolute zero.


What are Hydrides?

Hydrides are compounds composed of two different elements, one of them being hydrogen. The following summary is brief and hardly begins to indicate the extent of the world of hydrides. For instance, there are thousands of carbon-hydrogen hydrides.


Methane (CH4), for one, is the elemental building block for the entire world of hydrocarbon chemistry. This colorless, odorless gas is also the primary constituent of ordinary natural gas, sometimes called swamp gas. (This name comes from the fact that methane is a natural byproduct of decaying vegetation.)

As a popular household, commercial, and industrial heating fuel, natural gas is a significant economic commodity. As described earlier in this chapter, methane is also the primary ingredient in the commercial production of hydrogen.


A close cousin of methane is ethane, C2H6. It is also a colorless, odorless gas. Ethane is a common ingredient in natural gas, so much of it is used as a heating fuel. It is also used in the petrochemical industry as a base for many kinds of plastics.


Butane gas, C4H10, is also colorless, odorless, and highly volatile. This hydrocarbon has two forms, or isomers. In the instance where the four carbon atoms are connected in a straight chain, the gas is called n-butane, or normal-butane. Its isomer, one where the same four carbon atoms comprise a branched chain, is called isobutane.


Ammonia, NH3, is a colorless gas that has a distinctive choking odor. It is widely used as a solvent, a refrigerant, and a source of nitrates for chemical fertilizers.


Phosphine, PH3, is an extremely poisonous gas that has a choking, garlic odor. Current applications include manufacturing processes for certain classes of plastics and flameresistant cotton fabrics.

Markownikoff rule

When adding hydrogen halides to non-symmetrically formed (unsaturated) hydrocarbons, the halogen atom binds to the carbon with the smallest number of hydrogen atoms.

How was the Markownikoff rule formulated?

The Markownikoff rule was originally formulated by Markownikoff (Markovnikov) to generalize the orientation of hydrogen Halide additions to simple alkenes.

Markownikoff rule for polar addition

This rule of Markovnikov was extended to polar addition reactions as follows.

During the heterolytic addition of a polar molecule to an alkene or alkine, the most electronegative (nucleophilic) atom (or part) of the polar molecule binds to the carbon atom with the smallest number of hydrogen atoms.

This is an indirect statement from the current mechanistic observation that the most electropositive atom or part of the polar molecule (electrophile) binds to the end of multiple bonds that would result in the most stable carbene ion (than a carbene ion is or is not formed as a reaction intermediate in the addition reaction). Addition in the opposite direction is commonly referred to as anti-Markovnikov addition.

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