How many valence electrons does helium(He) have?

The valence electrons of helium are two and the total number of electrons is two. The symbol for the helium element is ‘He’. Helium does not participate in chemical reactions and bond formation. Therefore, helium is an inert element. This article discusses in detail the valence electrons of helium.

What are the valence electrons of helium(He)?

The total number of electrons in the last shell of helium is called the valence electron of helium. The total number of electrons in the last shell of an element after electron configuration is called the valence electrons.

The valence electrons are in the last shell of the element. However, the valence electrons of the transition elements may be in the inner orbital.

Valence Electrons of helium
Valence Electrons of Helium

Helium is the second element of the periodic table. The atomic number of helium is two. That is, the number of electrons in a helium atom is 2. The electron configuration of helium is 1s2.

The electron configuration of helium shows that there are a total of two electrons in the last shell(orbit) of helium. So, the valence electrons of helium are two.

Determining the number of valence electrons in helium

The total number of electrons in the last shell(orbit) of an atom is the valence electron. To determine the valence electrons, one must know the total number of electrons in the last shell of that element.

To know the number of electrons in the last shell, one must first know well about the electron configuration of that element. This article has some basic ideas about electron configuration. However, click here for details about electron configuration. A few steps need to be followed to diagnose helium valence electrons.

Step-1: Determining the total number of electrons

First you need to know the total number of electrons in the helium atom. For this, the atomic number of helium elements must be known. The atomic number is the number of protons in that element.

And electrons equal to protons are in that atom. The periodic table shows that the atomic number of helium is two. That is, the total number of electrons in the helium atom is two.

Helium electron configuration
Helium electron configuration

Step-2: Need to do electron configuration

In this step, you have to arrange the electrons of helium. Scientist Niels Bohr was the first to give an idea of the atom’s orbit. He provided a model of the atom in 1913. The complete idea of the orbit is given there.

The electrons of the atom revolve around the nucleus in a certain circular path. These circular paths are called orbit. These orbits are expressed by n. [ n = 1,2 3 4 . . .]

K is the name of the first orbit, L is the second, M is the third, N is the name of the fourth orbit. The electron holding capacity of each orbit is 2n2. [Where, n = 1,2 3,4. . .]

Now,
n = 1 for K orbit.
The electron holding capacity of K orbit is 2n2 = 2 × 12 = 2 electrons.

For L orbit, n = 2.
The electron holding capacity of the L orbit is 2n2 = 2 × 22 = 8 electrons.

n=3 for M orbit.
The maximum electron holding capacity in M orbit is 2n2 = 2 × 3= 18 electrons.

n=4 for N orbit.
The maximum electron holding capacity in N orbit is 2n2 = 2 × 32 = 32 electrons.

electron configuration
Electron Configuration

Also, the German physicist Aufbau first proposed an idea of electron configuration through sub-orbits. The Aufbau method is to do electron configuration through the sub-energy level. These sub-orbitals are expressed by ‘l’.

The Aufbau principle is that the electrons present in the atom will first complete the lowest energy orbital and then gradually continue to complete the higher energy orbital.

These orbitals are named s, p, d, f. The electron holding capacity of these orbitals is s = 2, p = 6, d = 10 and f = 14. The Aufbau electron configuration method is 1 s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d.

However, valence electrons can be easily identified by arranging electrons according to the Bohr principle. According to the Bohr principle, the first shell of helium has two electrons and the electron configuration of helium is 1s2.

Step-3: Determining the valence shell(orbit) and calculate total electrons

The third step is to calculate the total number of electrons in the last orbit. And we already know that the total number of electrons in the last orbit is the valence electron. The electron configuration of helium shows that there are a total of two electrons in the last orbit. Therefore, the number of valence electrons in helium is two.

Determination of the valency and valence electrons of helium

The electron configuration of helium is 1s2. The ability of an atom of an element to combine with another atom during the formation of a compound is called valency. Helium is an inert element. Therefore, the valency of helium is zero.

On the other hand, the number of electrons in the last orbit of an element is the valence electrons of that element. The last orbit of helium has 2 electrons. Therefore, the valence electron of helium is 2. Therefore, we can say that the valency of helium is zero and the valence electron is two.

valence electrons of helium
Valence Electrons of Helium

Reasons for placing helium in group-18 of the periodic table

Helium electron configuration is 1s2. The electron configuration of helium shows that the number of electrons in the last orbit of the helium atom is 2. We know that the number of electrons in the last orbit of an element is the number of groups in that element.

Accordingly, the group of helium is two but helium is an inert element. All inert elements are placed in group number 18 in the periodic table. Therefore, helium is placed in group-18 instead of group-2.

Why is helium an inert gas?

The elements in group-18 of the periodic table are inert gases. The inert gases of Group-18 are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). We know that the element in group-18 is helium(He).

The electron configuration of helium shows that the orbit at the end of helium is filled with electrons. Helium does not want to exchange or share any electrons because the last orbit of helium is full of electrons.

And helium does not form any compounds because it does not share any electrons. They do not participate in chemical bonding and chemical reactions. For this, they are called inert elements. The inert elements are in the form of gases at normal temperatures. For this, inert elements are called inert gases.

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