Hydrogen Chemical Properties (25 Facts You Should Know)

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H or hydrogen is the 1st element of the periodic table that exists as H2 in molecular form. We will discuss hydrogen in detail in this article.

Hydrogen is the lightest element on the earth and a diatomic homogeneous molecule. It is an odorless, colorless, and tasteless molecule that is most abundant in nature. Almost found 75% roughly in the universe. It is non-metallic and forms a covalent bond between hydrogen molecules.

It plays a crucial role in an acid-base reaction because if it is present in a molecule then it should be considered as acid or in the form of hydroxide form with a bond with O then the molecule is called the base. Now we will discuss the basic chemical properties of hydrogen with proper explanation in the following article.

1.Hydrogen symbol

The atomic symbol is that to express an atom by one or two letters and for a molecule, it should be called a molecular symbol. Let us predict the atomic symbol of hydrogen.

The atomic symbol of hydrogen is “H” as the name start with the English alphabet “H”. Also, for the molecular form, two hydrogen atoms are mixed to form hydrogen molecules. So, in the molecular form, the number of atoms is written as a suffix of the atomic symbol, the molecular symbol of hydrogen is “H2”.

2. Hydrogen group in the periodic table

A column of the periodic table where the element is placed by the atomic number is called a group. Let us predict the group of hydrogen in the periodic table.

The group of hydrogen in the periodic table is 1. Because it has similar properties to alkali metals, it can easily form cations by donating an electron. So, it is placed in the 1st group as an element.

3. Hydrogen period in the periodic table

The horizontal rows of the periodic table are called a period and correspond to the successive occupation of orbitals of the valence shell. Now predict the period of the hydrogen.

Hydrogen is belonged to period 1 in the periodic table because it has one electron in the valence shell so it is placed in the first position of the periodic table in the period and also in the group.

4. Hydrogen block in the periodic table

The block of the periodic table is known as the set of atomic orbitals of an element where the valence electrons are lying. Let us predict the block of the hydrogen.

Hydrogen is an s block element because the valence electrons present in the orbital is s or the outermost orbital of the hydrogen is s, so it belongs to s block element like alkali metals. There are only four blocks present in the periodic table, they are s,p,d, and f according to the orbitals.

5. Hydrogen atomic number

The number of protons present in the nucleus is called the atomic number of that particular element. Let us find the atomic number of the hydrogen.

The atomic number of hydrogen is 1, which means it has only one proton and also it has only one electron because we know the number of protons is always equal to the number of electrons and for this reason, they become neutral due to the neutralization of equal and opposite charges.

6. Hydrogen atomic Weight

Atomic weight is the mass of one atom of that particular element of the ratio of some standard value. Let us calculate the atomic weight of hydrogen.

The atomic weight of hydrogen on the 12C scale is 1 which means the weight of hydrogen is the 12th part of the weight of the carbon element. The original atomic weight of hydrogen is 1.00784, it is because the atomic weight is the average weight of all the isotopes of the element.

7. Hydrogen Electronegativity according to Pauling

According to Pauling electronegativity is defined as the power of an atom in a molecule to attract electrons to itself. Let us predict the electronegativity of hydrogen.

The electronegativity of hydrogen according to the Pauling scale is 2.20, which means it is more electronegative in nature and can attract electrons towards itself. The most electronegative atom as per the Pauling scale in the periodic table is fluorine having 4.0 electronegativity.

8. Hydrogen atomic Density

The atomic density is the number of atoms or nuclides per cm3 or in a unit volume of atoms in a material. Let us calculate the atomic density of hydrogen.

The atomic density of hydrogen is 0.0899 g/cm3 which can be calculated the diving the mass of the hydrogen by its volume. Atomic density means the number of atoms present per unit volume but the atomic number is the number of electrons present in the valence and inner orbital.

  • Density is calculated by the formula, atomic density = atomic mass / atomic volume.
  • The atomic mass or weight of the hydrogen atom is 1.00784 g
  • The volume of the hydrogen molecule is 22.4 liter at STP as per Avogardo’s calculation
  • So, for hydrogen atoms, the volume is 22.4/2 = 11.2 liter as it is diatomic.
  • So, the atomic density of the hydrogen atom is, 1.00784/11.2 = 0.089985714 g/cm3

9. Hydrogen melting point

The point where a substance changes its solid state to a liquid or the temperature where the change occurs as atmospheric pressure. Let us find the melting point of the hydrogen atom.

The melting point of the hydrogen atom is -259.20 C or 13.8 K temperature because at room temperature hydrogen exists as a gaseous form where all the atoms in the hydrogen plie in a disordered manner due to higher energy, so if we decrease the temperature then the elements are placed in good arrangement.

10. Hydrogen boiling point

The boiling point is where the vapor pressure of the substance becomes equal to the atmospheric pressure. Let us find the boiling point of hydrogen.

The boiling point of the hydrogen atom is -252.8790 C or 20.271 K because it exists in gaseous form at room temperature so boiling point of the hydrogen atom is also very low even at negative temperature. The van der Waal’s force of attraction is low so less energy of heat is required for boiling hydrogen.

The gaseous form of hydrogen exists at room temperature or higher temperature from its boiling point.

11. Hydrogen Van der waals radius

Van der Waal’s radius is the imaginary measurement between two atoms where they are not bound ionically or covalently. Let us find van der Waal’s radius of hydrogen.

The van der Waal’s radius of the hydrogen molecule is 1.1 *102 pm because the value is close to the value of 1.2 *102 which is proposed by Pauling. Van der Waal’s radius is calculated by the mathematical formula considering the distance between two atoms, where atoms are spheres.

  • The formula used the find out the Van der Waal’s radius is, Rv = dA-A / 2
  • Where RV is the Van Waal’sal’s radius of the molecule
  • dA-A is the summation of the radius of two atomic spheres or the distance between the center of two spheres.

12. Hydrogen ionic radius

Ionic radius is the summation of the radius of cation and anion respectively, for an ionic molecule in a crystal structure. Let us find out the ionic radius of hydrogen.

The ionic radius of hydrogen is 120 pm is the same as the covalent radius because for hydrogen the cation and anion are the same and it is not an ionic molecule, rather it forms by the covalent interaction between two hydrogen atoms.

13. Hydrogen isotopes

The elements have same number of protons but different number of neutrons of substances are called isotopes of that original element. Let us discuss isotopes of hydrogen.

Hydrogen has three types of proton based on neutron and they are discussed below,

  • Hydrogen (1H1) – It is the more stable form of hydrogen among all other isotopes, having 1 electron and 1 proton, but it has zero neutrons.
  • Deuterium (2H1) – It is also a stable isotope of hydrogen and its abundance is very much lower than hydrogen, it has 1 electron, and 1 proton but two neutrons.
  • Tritium (3H1) – It is the heaviest isotope of hydrogen having very lower stability (half-life is 12 years) and very little abundance in the atmosphere. It has one electron like others but the number of neutrons is 3. It can emitted β particles.

14. Hydrogen electronic shell

Electronic shells are those which are surrounding the nucleus and containing a specific number of electrons in it. Let us discuss the electronic shell of hydrogen.

The number of an electronic shell of hydrogen around a nucleus is 1, which is s orbital. Because there is only one electronic shell present and the s orbital has more penetrating power which is a present very nearest position to the nucleus, that shell of hydrogen is s orbital.

15. Hydrogen electron configurations

The electronic configuration is an arrangement of the electrons in available orbital by considering Hund’s rule. Let us discuss the electronic configuration of hydrogen.

The electronic configuration of hydrogen is 1s1 because it has only one electron and that electron should be placed to the nearest orbital of the nucleus that is s orbital and for the 1st orbital where the principal quantum number is 1. So, it is denoted as 1s1.

Here the first number stands for the principle quantum number, the letter is for orbital and the suffix number is the number of electrons.

16. Hydrogen energy of first ionization

The energy required for the removal of the last valence electrons from the respective orbital is called the first ionization energy. Let us predict the first ionization of hydrogen.

The first ionization occurs for hydrogen from its s orbital to remove one electron. The energy required for the first ionization of a hydrogen atom is 13.6 EV because there is much energy required removal of electrons from the orbital which is nearest to the nucleus and the force of attraction is very high.

Not necessary to remove electrons always for the s orbital, it depends on the valence orbital, if the valence orbital will be p, d or f then the electron is removed from the p, d, and f orbital respectively.

17. Hydrogen energy of second ionization

Second ionization is the removal of the outermost electron from its +1 oxidation state of the element. Let us see the second ionization of hydrogen.

There is no second ionization possible for the hydrogen because, at the +1 state of hydrogen that is H+, there are no electrons left for removal. Hydrogen has only one electron and this electron is removed for the first ionization so nothing is left for 2nd ionization.

Though there is not possible for 2nd ionization so the energy of the 2nd ionization of the hydrogen is not predicted.

18. Hydrogen energy of third ionization

Third ionization is the removal of electrons from the respective orbital having a +2 oxidation state of the element. Let us see the third ionization of hydrogen.

There is no third ionization observed for the hydrogen because there is no second ionization and the third ionization occurs after the second one. So, if there 2nd ionization is not possible then the third ionization is impossible for hydrogen, and the energy will be unpredicted.

19. Hydrogen oxidation states

The oxidation state is the charge present over the element after the removal of such numbers of an electron to form a stable bond. Let us predict the oxidation state of hydrogen.

The stable oxidation state of hydrogen is +1 because it has only one electron in the s orbital and when the electron is removed then it can form a stable single bond, so it has +1 oxidation state as the s orbital contains a maximum of two electrons.

20. Hydrogen CAS number

CAS registry number is a special kind of number a unique unmistakable identifier number provided worldwide. Let us know the CAS number of hydrogen.

The CAS number of the hydrogen molecule is 1337-74-0 and the hydrogen atom is 12385-13-6, which is given by the chemical abstracts service. Which is different from the CAS number of the other element.

21. Hydrogen Chem Spider ID

The Royal Society of Chemistry gives a particular unique number for every chemical element which is knowns as Chem Spider ID. Let us discuss it for hydrogen.

The Chem Spider ID for hydrogen is 4515072, which is given by the royal society of chemistry, and by using this number we can evaluate all the chemical data related to the hydrogen atom. like CAS number it is also different for all elements.

22. Hydrogen allotropic forms

Having the same chemical but different physical properties of different structural forms of the same element. Let us discuss the allotropic form of hydrogen.

Two allotropic forms of hydrogen exist, one is ortho hydrogen and the other is para hydrogen. Which can be discussed below,

  • Ortho hydrogen – the spin of the nuclei in this hydrogen in the same direction which means in a parallel spin.
  • Para hydrogen – the spin of the nuclei in this type of hydrogen in the opposite direction which means anti-parallel spin. Due to the opposite spin, it has lower internal energy.

At 25K temperature hydrogen has an equilibrium mixture of 99% of para and 1% of ortho hydrogen but at room temperature, the equilibrium changed to 75%(para-hydrogen)  and 25%(ortho-hydrogen).

23. Hydrogen chemical classification

Chemical classification is the classified the element by its reactive nature, or they cause hazards to the human body. Let us know the chemical classification of hydrogen.

Hydrogen is classified as non-metal at room temperature because it does not produce heat and electricity and also the density of the element is very low.

24. Hydrogen state at room temperature

The condition is characterized by the element at room temperature and experimental pressure. Let us predict the state of hydrogen at room temperature.

Hydrogen exists in a gaseous state at room temperature because it has lower van der Waal’s interaction so the atoms exist very far from each other. The randomness of the atoms is very high at room temperature.

The gaseous state of the hydrogen can be changed to liquid or solid at a very low temperature, where the randomness will be decreased for the hydrogen atom.

25. Is hydrogen paramagnetic?

The materials tend to get weakly magnetized in the direction of the magnetizing field when placed in a magnetic field. Let us see whether hydrogen is paramagnetic or not.

The hydrogen atom is paramagnetic in nature, due to the presence of one unpaired electron but the hydrogen molecule is not paramagnetic because it has paired up electrons. Due to paired form, hydrogen molecule is diamagnetic in nature.

So, we have to check the number of electrons present in the valence orbital for an element whether it is paired form or unpaired form then it will be paramagnetic or diamagnetic accordingly.

Conclusion

From the above discuss the hydrogen atom, we can conclude that hydrogen is s block element having only one electron in it, which is also its valence electron. It has three isotopes and two allotropic forms. It is placed also at group VIIA like halogen, it has only one electron to donate so it is often called a vagabond atom.