Bohr Model of Boron Atom

Aug 19, 2021 | SCIENCE

The Bohr Model of the Boron Atom

Boron is a chemical element with an atomic number 5 and symbol B. It is the lightest element in the boron group and has three valence electrons for forming covalent bonds. Boron combines with other elements to create compounds such as boric acid, borax, and boron carbide. This article describes the structure of the Boron atom when classified using the Bohr model.

Bohr Model of Boron

Bohr Model of Boron

What is the Bohr Model?

The Bohr model of an atom shows that the electrons revolve in different orbits with varying energy around the nucleus. This model assumes that electrons are similar to planets, and the nucleus is like the sun in the solar system. Also, according to this model, the energy of an electron is quantized. It means that electrons can belong to an energy level or another, but nothing in between.

The Bohr model is perhaps the most influential theory in physics because it predicted atomic energy levels and justified them with fundamental physical constants. The success of this work was mainly due to its ability to explain Rydberg’s formula for spectral emissions lines from hydrogen atoms which had never been experimentally confirmed until then.

The Bohr Model of Boron

Bohr’s Model of Boron describes the electrons orbiting and their visual representation around the tiny nucleus. It makes use of various electron shells like K, L, M, N, and others. Each shell holds a particular number of electrons, with the shell closest to the nucleus having the least energy. As the shell goes farther away, the energy levels grow.

Boron’s Bohr Model is made up of a nucleus with six neutrons and 5 protons. Two electron shells, namely K-shell and L-shell, surround the nucleus. Additionally, there are 3 electrons in the outermost shell of the Bohr diagram, which are the valence electrons.

Bohr Model of Boron
Neutrons: 6 | Protons: 5 | Electrons: 5
Electron Shells: 2 | Electrons in K-Shell (I): 2 | Electrons in L-Shell (II): 3
Total Number of Valence electrons: 3

Drawing the Bohr Atom Using the Bohr model
Bohr’s diagram is easy to draw. Here is a simple way to mark the Bohr diagram of the Boron atom in a few steps.


  1. Calculate the number of protons, electrons, and neutrons in the Boron atom
    In an atom, we have protons which are positively charged particles, and electrons are the negatively charged particles. Neutrons are the uncharged particles in an atom, and it constitutes the atom nuclei along with the protons. The negatively charged particles orbit the nucleus of the atom.
  2. Take a look at the atomic number of an atom to find the number of protons.
    Hint – If the atomic number is 2, then the number of protons is 2. Hence, we know that the atomic number for Boron is five, and therefore, we have 5 protons in the atom of Boron.
  3. Find the number of neutrons in an atom using the following formula:
    The number of neutrons in an atom = Atomic mass of the atom – Number of protons in an atom (N = A – Z)
  4. Round up the atomic mass to the closest whole number.
    For example, if an atom has an atomic mass of 20.99 and 14 protons, you can round the mass up to the nearest whole number 21.
    Number of neutrons = 21-14 = 7.
    The same approach is used to find the number of neutrons in a Boron atom. The atomic mass of Boronis 10.811, rounded off to 11. And the number of protons in Boron is 5. therefore, the number of neutrons in a boron atom is 11 – 5 = 6
  5. The number of electrons in any neutral atom equals the number of protons.
    Since the Boron atom is neutral, its electrons will be equal to the number of its protons.
    Hence, in a Boron atom – Number of electrons = 5 | Number of protons = 5 | Number of neutrons = 6

The Nucleus of the Boron Atom in Bohr’s Model

The nucleus is a thick and small area consisting of protons and neutrons in an atom. Hence, in Bohr’s model, we have a small circle representing the protons and neutrons of the Boron atom.
An electron shell may be thought of as an orbit followed by electrons around an atom’s nucleus.”

The First Electron Shell

Bohr model of Boron

Bohr model of Boron

The K-shell is the first electron shell closest to the atom’s nucleus, holding up to two electrons. Since we know that Boron consists of 5 electrons, we can put two electrons in the K-shell next to one another. And we have the first shell with 2 electrons, as seen in the diagram.
The boron atom has 5 electrons in total, and from that, we have used two of them for the first shell – K-shell.
5 – 2 = 3 electrons
Hence, we have 3 electrons with us now, which should be used in the next shell – the L-shell of the Boron atom.

The Second Electron Shell

The second shell of an atom in Bohr’s model is called an L-shell. It can hold up to 8 electrons maximum. Move to this shell after filling the first K-shell. There are already 2 electrons used in the first shell. Put the remaining three electrons in the second shell. Here, electrons can be filled one at a time in the clockwise direction.
It is essential to stick to the clock position – 12, 3, 6, and 9 o’clock. The remaining 3 electrons of the Boron atom are then placed into the L-shell. Move form the top in a clockwise direction. Put out 1 electron at a time.

Unlike the first shell, the second shell can hold electrons in any direction. This is because the first shell is said to be the noble gas configuration. Hence, the electrons in the first shell must be in the nearest noble gas configuration as possible. In the case of the second shell, there are no restrictions so that the electrons can be filled in any direction.

However, in the case of the fourth shell, there is a restriction. It is said to be the second noble gas configuration. Hence, the electrons must be in the nearest noble gas configuration as possible.As you move along the periodic table, elements become progressively less reactive. This is because the outermost electrons are being filled with more energy and are more tightly held to the nucleus. In this way, the higher energy electrons are more difficult to remove, leaving the remaining electrons with less energy.

Similarly, the outermost electrons are also the most difficult to remove. This is because they are the most distant from the nucleus and thus have the largest electrostatic repulsion from the positively charged nucleus. By convention, the electrons are numbered from the top-down, with the first shell K-shell associated with the highest energy level and the L-shell associated with the lowest level for 8 atomic numbers. This is  the complete Bohr’s model of the Boron atom.

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