How Many Valence Electrons Does Helium (He) Have? [Valency of He]

Helium, a chemical element with the symbol He and atomic number 2, is a colorless, odorless, tasteless inert gas. It is the second lightest and abundant chemical species after hydrogen. It has the lowest boiling point among the elements in the periodic table.

It is mostly found in a free state and formed in large amounts during the nuclear fusion of hydrogen in stars. Helium is the only element that cannot be solidified by sufficient cooling at normal atmospheric temperature and pressure. About 23% of the mass of the universe is constituted in the form of helium and mostly helium is founded in the concentrated form inside stars.

You are here to know valence electrons and the valency of helium, aren’t you? But before that let's have some ideas about what these terms are:

Difference Between Valence Electrons and Valency

Valence electrons are the total number of electrons present in the outermost shell of an atom (i.e. in outermost orbital). The valence electrons for a neutral atom is always definite, it cannot be varied (more or less) in any condition for a particular atom and may or may not be equal to its valency.

Valency is defined as the total number of electrons an atom can lose, gain, or share at the time of bond formation to get a stable electronic configuration i.e. to complete an octet. The valency of an atom can be variable in different compounds or chemical reactions due to the different bonding circumstances. Most of the time valency varies/changes due to change in oxidation and reduction states.

Helium (He) Valence Electrons

There are four simple steps to find out the valence electrons for helium atom which are:

Step 1: Find the Atomic Number

To find out the atomic number of helium, we can use the periodic table. With the help of the periodic table, we can easily see that the atomic number of helium is 2. As its atomic number is 2, it has two protons, and for neutral helium, the number of protons is always equal to the number of electrons i.e. have two-electron in their nucleus.

Step 2: Write Electron Configuration

Electron configuration is the arrangement of electrons on the orbitals. The helium atom has only one electron on its shell, we have to put only one electron in its orbital and that will go in the 1s orbital as the S orbital can hold a maximum of two electrons, and is closer to the nucleus.

Helium electron configuration He (2) = 1s2 (complete configuration).

Step3: Determine Valence Shell

As we know, the valence shell of an atom can be found from the highest number of principle quantum numbers which is expressed in the term of n, and in 1s2, the highest value of n is 1 so that the valence shell of He is 1s2.

Step 4: Find Valence Electrons

The total number of electrons present in the valence shell of an atom is called valence electrons, and there is only one electron present in the valence shell of helium (1s2). Thus, helium has two valence electrons.

Valency of Helium (He)

There are many different ways to find out the valency of an atom which reflects the ability of an atom to bond with other atoms. Valence describes how easily an atom or a free radical can combine with other chemical species. The valency of an atom is determined based on the number of electrons lost, gained, or shared with another atom at the time of bond formation.

An atom is said to be stable when its outermost shells have eight electrons (except H & He). If the total number of electrons in outermost shells is between one to four, the atom has positive valency and if electrons are between four to eight, the valency is calculated by subtracting from eight and valency will be zero. Atoms having four outermost electrons possess both positive and negative valency, and atoms having eight outermost electrons, valency will be zero (i.e. noble gases).

Noble gases like helium have two valence electrons so it does not require to lose or gain electrons to complete its energy shell i.e. stable duplet. So that they do not have any tendency to combine with other elements which makes the valency of helium zero.

We can also find the valency of helium with the help of the periodic table. As helium belongs to group 8A which are groups of noble gases having valency zero.

Note: Helium is the only noble gas that has a complete duplet state, the rest of all noble gases have complete octet states.