The chemical symbol of Hydrogen is H. The hydrogen atom is the first member of the modern periodic table with 1 atomic number and 1 mass number.
The properties of hydrogen are unique and hence, its position was always in debate. The properties of the hydrogen atom are similar to both alkali metals and halogens. Therefore, the hydrogen atom shows +1 and -1 oxidation states depending upon the electronegativity of the combining atom.
Many of you have doubts in your mind regarding if hydrogen atom contains neutrons or not. Yes, that seems little confusing.
So, Does Hydrogen have neutron? No, the hydrogen atom (Protium) does not contain neutron because of hydrogen’s small atomic size. It has only one electron and one proton because neutron cannot accommodate itself in the small-sized nucleus of the Hydrogen atom.
The neutrons in an atom stabilize its nucleus by interacting strongly with its proton. This strong neutron-proton interaction overcomes the proton-proton electrostatic repulsion.
But, the hydrogen atom has only one proton, which cannot show repulsion owing to the absence of other protons. Hence, the Hydrogen atom does not have a neutron for the stabilization of the nucleus.
Therefore, the hydrogen atom is unstable and exists in diatomic form as dihydrogen gas (H2).
The hydrogen atom exists as hydrogen gas (H2) at standard temperature and pressure as the hydrogen atom is very reactive and unstable in its free state. The hydrogen gas is tasteless, odorless, and colorless.
The hydrogen atom has been discovered as hydrogen gas by Henry Cavendish in 1766. He observed that hydrogen gas exists as a discrete element and it forms water on burning. It was named Hydrogen by Antoine Lavoisier in 1783.
The hydrogen atom is the lightest element and has a 1.008 g atomic weight. In the universe, it is present in abundant nature. It almost contributes about 75 % of the baryonic mass.
The hydrogen atom adopts a hexagonal crystal structure and is diamagnetic in nature. It is present in various phases such as liquid hydrogen, hydrogen gas, solid hydrogen, metal hydrogen, and slush hydrogen.
Let me clear the core reasons in a simple and elaborative way. Before moving directly over reasons, firstly readout below the terminologies to get familiar with this concept.
Electron, Proton, and Neutron
Dalton said that the atom is the smallest quantity of matter. But, later research proved that an atom consists of three subatomic particles, which are electron, neutron, and proton.
First of all, negatively charged particles i.e., electrons were discovered by the cathode ray experiment by J. J. Thomson in 1897. The credit for the discovery of proton was given to Rutherford in 1920. Although experiments were done by Goldstein in 1886, he did not name those positive charge particles.
The neutrons, neutral particles, were discovered by the bombardment of alpha particles on Beryllium by James Chadwick in 1932.
The charge on the proton and an electron is equal (1.6022 * 10-19 C) and opposite i.e., negative charge on the electron and positive charge on the proton. Neutron is neutral and does not carry any charge.
Electron is the lightest of three subatomic particles having a mass of 9.1 * 10-31 kg. However, the neutron is slightly heavier than the proton. The mass of proton and neutron are 1.6726 * 10-27 kg and 1.6749 * 10-27 kg, respectively.
The proton and neutrons are present in the nucleus of the atom whereas the electrons rotate around the nucleus.
The mass of the atom is concentrated in the nucleus owing to the large mass of protons and neutrons as compared to electrons.
On the basis of the number of electrons, protons, and neutrons, we can define three isotopes of the Hydrogen atom.
Let us understand these isotopes of the hydrogen atom.
What is Isotope?
Isotopes of the Hydrogen atom
Isotopes are atoms of the element, which have the same atomic number but a different mass number.
There are three isotopes of the hydrogen atom, which are named Protium, Deuterium, and Tritium. The Protium isotope is the most abundant out of three isotopes whereas Deuterium, and Tritium isotopes are present in very minute quantities.
However, other unstable isotopes of the hydrogen atom have been prepared in laboratories but they are not available in nature. Hence, these unstable isotopes are not studied.
As we all know that, the atomic number of an atom is equal to the number of electrons in that atom and the mass number of an atom is defined as the summation of the number of protons and number of neutrons present in an atom.
For a neutral atom, the number of protons is equal to the number of electrons in an atom to neutralize the charges.
Hence, we can say that Isotopes of Hydrogen atoms will have the same number of electrons/protons but a different number of neutrons in the nucleus.
An atom is represented as a/z x, where X is the chemical symbol of the atom, A and Z are mass number and atomic number, respectively.
Therefore, the nuclear symbol of Protium, Deuterium and Tritium are represented as 1/1H, 2/1H, and 3/1H, respectively.
But, Why Deuterium and Tritium consist of neutrons?
It indicates that the atomic number and mass number of Protium are 1 and 1, respectively. The mass number of Deuterium and tritium isotope is 2 and 3, respectively.
Hence, the hydrogen atom specifically Protium contains only one proton, and one electron as a proton will balance the negative charge of the electron. It does not have any neutron in its nucleus.
However, Deuterium and Tritium isotopes of hydrogen contain one electron and one proton but also consist of one and two neutrons, respectively.
Now, we came to know that the hydrogen atom does not have neutrons. But, the question will come into our mind that why it does not have neutrons?
So, let us find the answer to this question.
Why Hydrogen does not have neutrons?
There are various reasons in the literature for not having neutrons in the hydrogen atom. Let us see these reasons one by one.
The first reason behind the absence of neutrons in the Hydrogen atom is the small size of its nucleus.
Small Hydrogen atomic size
The small size nucleus cannot accommodate heavy neutrons. It can accommodate either proton or neutron as their sizes are comparable.
For maintaining electroneutrality of the hydrogen atom, it allows the proton instead of neutrons.
The other reason for the absence of neutron in the Hydrogen atom is as follows:
The neutrons also stabilize the nucleus by interacting with the proton. The proton-neutron interaction is stronger than proton-proton repulsion.
Hence, it diminishes the effect of proton-proton electrostatic repulsion owing to the same charge.
The hydrogen atom contains only one proton, which cannot repel itself. Therefore, the hydrogen atom, especially Protium (1/1H) does not require neutrons for stabilization of the nucleus.
It proofs that hydrogen does not have neutron in its nucleus.
Uses of Hydrogen
1. The hydrogen gas is used for the up-gradation of the fossil fuels by Hydrogenolysis, which means breaking of bond on the addition of the hydrogen gas. For example Removal of Sulphur as hydrogen sulfide gas from liquid fossil fuels
R-S-R + 2H2 —-> 2RH + H2S
2. Hydrogen gas is also used for hydrogenation, which means the addition of hydrogen gas to the substrate. For example The formation of ammonia by the Haber-Bosch Process
N2 + 3H2 —-> 2NH3
3. Hydrogen gas has low viscosity, low density, and high specific heat and thermal conductivity owing to its lightweight. Hence, it is used as the coolant in generators as well as in power stations.
4. Hydrogen forms several organic compounds and also metal hydride.
In a nutshell, the hydrogen atom does not contain neutrons because
1. The size of the nucleus of the Hydrogen atom is very small and hence, the nucleus cannot accommodate neutrons.
2) The neutrons stabilize the nucleus by interacting with its proton to reduce the effect of proton-proton repulsion. As hydrogen atom contains only one proton.
Therefore, it does not have other protons for repulsion, which excludes the requirement of the neutron in the hydrogen atom.
Both these factors lead to the instability of the hydrogen atom in its native state and it is found in diatomic form as hydrogen gas (H2).