Boron, a chemicalelement with the symbol B and atomic number 5, is a low-abundance element foundin the solar system. It is a non-metallic element with a black-brown appearance. Ithas mainly two naturally occurring and stable isotopes which are 11B (80.1%),and 10B (19.9%).

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Borax (Na2.8H2O), orthoboricacid (H3BO3), diborane (B2H6), Boron trifluoride (BF3), Borane (BH3) are some of thecommon compounds of boron. Boron normally does not react with air at roomtemperature, but at higher temperatures, it started burning and forms borontrioxide.

4 B + 3 O2→ 2 B2O3

You are here toknow valence electrons of a boron atom, aren’t you? Don’t worry along with boronvalence electrons we will explain its valency also. But before that let’s havesome basic ideas about what these two terms are:

Difference BetweenValence Electrons and Valency

Valence electronsare 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 alwaysdefinite, it cannot be varied (more or less) in any condition for a particularatom and may or may not be equal to its valency.


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

Boron (B) ValenceElectrons

There are foursimple steps to find out the valence electrons for boron atom which are:

Step 1: Find theAtomic Number


To find out theatomic number of boron, we can use the periodic table. With the help of theperiodic table, we can easily see that the atomic number of boron is 5. As itsatomic number is 5, it has five protons, and for neutral boron, the number ofprotons are always equal to the number of electrons i.e. has five electrons inits nucleus.

Step 2: WriteElectron Configuration


Electronconfiguration is the arrangement of electrons on the orbitals. The boron atomhas a total of five electrons so, we have to put 5 electrons in orbitals. The electronswill be placed in different orbitals according to the energy level: <1s, 2s,2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f>. Now,

Boron electronconfiguration B (5) =1s22s22p1(completeconfiguration).

= 2s22p1(condensed configuration).

Step3: DetermineValence Shell

As we know, thevalence shell of an atom can be found from the highest number of principlequantum numbers which are expressed in the term of n, and in 2s22p1, thehighest value of n is 2 so that the valence shell of B is2s22p1.

Step 4: FindValence Electrons

The total number ofelectrons present in the valence shell of an atom are called valence electrons,and there are three electrons present in the valence shell of boron (2s22p1).Thus, the boron has three valence electrons.

Valency of Boron (B)

There are manydifferent ways to find out the valency of an atom which reflects the ability ofan atom to bond with other atoms. Valence describes how easily an atom or afree radical can combine with other chemical species. The valency of an atom isdetermined based on the number of electrons lost, gained, or shared withanother atom at the time of bond formation.

An atom is said tobe 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, thevalency is calculated by subtracting from eight and valency will be zero. Atomshaving four outermost electrons possess both positive and negative valency, andatoms having eight outermost electrons, valency will be zero (i.e. noblegases).

Elements like boroncan reach the stable state (nearest inert gas configuration) by losing 3outermost electrons or by getting 5 electrons.So that the valency of boron(B) is 3.

Note: Boron hasboth +3 & -3 valency states. If it loses three electrons to reach a stablestate i.e. He, its valency will be +3. But if it gains five electrons to reach a stablestate i.e. Ne, its valency will be -3 as explained above.

As we know boron isa non-metallic element so that is an electromotive and for electromotive elementslosing an electron is not a good option. This is the reason why boron has -3valency most of the time.

We can also findthe valency of boron with the help of the periodic table. As boron belongs togroup IIIa along with aluminum, gallium, indium, thallium, and nihonium. Andthese all elements possess a valency state of three.

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Boron is better known as metalloid as it can show characteristics of both metals and nonmetals. When boron reacts with high electropositive atoms like sodium or potassium, it acts as a non-metal. But when it reacts with lower electronegative atoms like fluorine, it behaves like metal and forms BF3 (Boron trifluoride).