How to Find the Valence Electrons for Boron Trihydride?
The total number of electrons in the last orbit of an element is called the valence electrons of that element. Two or more elements combine to form compounds.
The valence electrons of a compound are the sum of the total valence electrons of each element in that compound. Boron trihydride (Borane) consists of two atoms. One is a boron atom and the other is a hydrogen atom.
The valence electrons of boron trihydride are the sum of the total valence electrons of boron and hydrogen in the compound BH3. The boron trihydride compound has a total of six electrons in the last orbits of boron and hydrogen.
Hence, the total number of valence electrons in boron trihydride is six. To determine the valence electrons of a compound, the number of valence electrons in each element of the compound must be known.
This article discusses in detail how to determine the valence electrons of boron trihydride very easily. Hopefully, after reading this article you will know more about this topic.
How to easily determine the number of valence electrons of BH3?
The symbol form of boron trihydride is BH3. To determine the valence electrons of BH3, it is first necessary to know the valence electrons of the hydrogen and boron atoms.
To determine the valence electrons of boron trihydride we have to follow two steps. It is shown below:
Step 1: Determine the valence electrons of boron and hydrogen atoms
The atomic number of boron is 5. So its total number of electrons is five. The electron configuration of boron shows that it has three electrons in its last orbit.

We already know that the electrons in the last orbit of an element are the valence electrons of that element. Therefore, the valence electrons of boron are three.

On the other hand, the atomic number of hydrogen is 1. So its total number of electrons is one. The electron configuration of hydrogen shows that it has an electron in its last orbit. Therefore, the valence electrons of hydrogen are one.
Step 2: Determine the total number of valence electrons in the boron trihydride compound
Boron trihydride is a compound. It is composed of one boron atom and three hydrogen atoms.
Therefore, adding the valence electrons of one boron atom and the valence electrons of three hydrogen atoms can easily determine the valence electrons of boron trihydride.

Mathematical Analysis:
BH3
= 3 + (1×3)
= 6
Boron (B) | Hydrogen (H) | Boron trihydride (BH3) |
3 | 1 | 6 |
From the above mathematical analysis, we can see that the total number of electrons in the outermost orbit of boron trihydride is six. Therefore, the valence electrons of boron trihydride are six.
Why do you need to know the valence electrons of an element?
In addition to knowing the number of electrons of an element, it is also necessary to know the number of valence electrons of that element. The number of valence electrons of an element carries important properties of that element.
Many important properties of elements and compounds can be determined by valence electrons. Some important features are mentioned below:
- Determining the element’s position in the periodic table
- Determining the number of groups of elements in the periodic table
- Determining Valency
- Lewis dot formation
- Determination of the molecular structure of the compound
- Determination of bond pairs and non-pair electrons of compounds
Valence electrons are related to the characteristics of a compound. So we need to know the valence electrons of all the elements to determine the properties of compounds.