Silicon is a group 14 element and is denoted by the symbol Si. It has a high affinity towards oxygen due to which it rarely occurs in its pure form in nature.
It is a metalloid and a non-metal. It is the second most abundant mineral found on the earth’s surface. Silicate minerals compose around 90% of the earth’s crust. Different forms of silicon such as clays, stone, and silica sand.
Are you interested to know the Bohr model of silicon? If yes so this article will give you the Bohr model of silicon
Bohr Model of Silicon
The Bohr model is also known as the Bohr-Rutherford model as it was developed as a modification of the Rutherford model. It was given by Niel Bohr in 1913.
This model is used to illustrate the atomic composition in pictorial form. The different atomic particles such as electrons, protons, and neutrons are shown at their predicted positions.
To understand the atomic structure better we first need to comprehend the different parts and particles that constitute an atom. These are given below:
• Nucleus: It is the heart of an atom, located right at its center. It comprises positively charged protons and neutral neutrons.
• Proton: This name was given by Ernst Rutherford to the positively charged species existing inside the nucleus. These are denoted by the symbol p+.
• Neutrons: These are the neutral subatomic particles that are present inside the nucleus. These are denoted by the symbol n or n°.
• Electrons: These are the negatively charged subatomic particles that surround the nucleus of the atom. As per the Bohr-Rutherford model, the electrons revolve around the nucleus in fixed orbits or shells.
• Shells: These are the circular paths surrounding the atoms in which the electrons are said to revolve around the nucleus. Multiple numbers of shells are present in an atom depending upon the number of electrons it contains.
According to the Bohr model of the atom, the shells are named as K, L, M, N, etc., or 1, 2, 3, 4, etc. with the lowest value assigned to the shell located closest to the nucleus.
The shells are also known as energy levels. The shell closest to the nucleus is said to have the least energy, also known as the ground state while the one located farthest from the nucleus has the maximum amount of energy associated with it.
When an electron gets excited it jumps from the lower energy level to the higher energy level.
The farthest shell or outermost energy level of an atom is called the valence shell and the electrons that are located in this shell are known as valence electrons.
The Silicon atom has 14 protons and 14 neutrons, and 14 electrons revolve around its nucleus in three shells viz. K, L, and M.
|No. of Proton||14|
|No. of Neutron||14|
|Number of Electrons||14|
|Number of shells||3|
|Number of electrons in first (K) shell||2|
|Number of electrons in second (L) shell||8|
|Number of electrons in third (M) shell||4|
|Number of valence electrons||4|
Drawing Bohr Model of Silicon
Silicon belongs to the carbon family and is located in the 14th group of the Periodic table.
The above-shown Silicon box represents its various properties. The facts that can be derived from it are:
• The atomic number of Silicon is 14
• The electronic configuration of Silicon is 1s22s22p63s23p2.
• Silicon is represented by the symbol Si.
• The atomic mass of Silicon is 28.086.
To draw the Bohr model of silicon we shall first identify the number of atomic species present in this atom.
First, let us find out the number of protons in the Silicon atom.
The atomic number of an atom is always equal to the number of protons that an atom contains.
In the case of Silicon, the atomic number = 14
Therefore, number of protons in Silicon = Atomic Number of Silicon = 14
Now, finding the number of neutrons in the Silicon atom,
Number of neutrons = Atomic mass (rounding it up to the nearest whole number) –
Number of protons
As mentioned in the previous section, the atomic number of Silicon is 28.086, rounding it up to the nearest whole number gives 28.
Therefore, Number of neutrons in Silicon = 28 – 14 = 14
As the neutrons and protons are located in the nucleus of an atom, the nucleus of Silicon can now be drawn as follows:
Here, p+ represents proton and n° represents neutron.
Now, let us try to find the number of electrons in the Silicon atom,
As Number of electrons = Atomic number
Therefore, in the Silicon atom, number of electrons = Atomic Number = 14
This means that 14 electrons are revolving around the nucleus of the Silicon atom. Now, let us find the position of these electrons inside the atom.
The number of electrons that can be accommodated in a shell is given by the formula:
Maximum number of electrons in a shell (N) = 2n2
Where, n = No. of shell
Now, calculating the number of electrons that can be accommodated in the first (K) shell:
For the K shell, maximum number of electrons = 2 X (1)2 = 2
Hence, the K shell consists of two electrons, and the silicon atom after adding two electrons to its K shell looks like this:
Now calculating the maximum number of electrons that can be added to the L shell:
For L shell, maximum number of electrons = 2 X (2)2 = 8
Hence, eight electrons can be housed in the L shell.
Please note that electrons to any shell (except K shell) are always added in clockwise order. This is done by adding the first four electrons at 90° to each other and similarly adding the other electrons in a group of four.
Applying this to the silicon atom, after adding the first four electrons to the L shell the silicon atom looks like this:
Now, adding the remaining four electrons to the L shell, the silicon atom appears as follows:
Now calculating the maximum number of electrons to M shell
For M shell, Maximum number of electrons = 2 X (3)2 = 18
However, in the case of silicon, we are now left with only four electrons. These four electrons are added to the M shell in a clockwise manner. The final Bohr model of Silicon atom is drawn as follows:
Therefore, the final Bohr model of the Silicon atom consists of 14 protons, 14 neutrons, and 14 electrons.
The electrons are distributed in three shells as K shell consists of 2 electrons, L shell has 8 electrons, and M shell has 4 electrons. The number of valence electrons in the Silicon atom is four.
Deriving the Lewis Structure from Bohr Model
The Lewis structure represents the positions of valence electrons around the nucleus of an atom.
It is a pictorial presentation also known as electron dot structure as the electrons are shown in the form of dots and the nucleus is shown by using the atomic symbol of the atom.
Using the Bohr model of the atom drawn above, it can be deciphered that it contains 4 electrons in its valence shell. Hence, we can draw the Lewis structure of the Silicon atom as follows:
I have written multiple articles on the lewis structure of silicon compounds. Below are a few of them.
Question 1: How many shells are present in the silicon atom?
Answer: The silicon atom consists of 3 shells i.e. K, L, and M shells. These may also be called the first, second, and third shells of the atom.
Question 2: Calculate the number of valence electrons in the silicon atom.
Answer: The valence electrons are the electrons that participate in bonding when an atom forms a compound. These are housed in the shell located farthest from the nucleus of an atom.
In the case of the silicon atom, the M shell is farthest from the nucleus, hence, the electrons in this shell are the valence electrons for silicon. Therefore, silicon consists of 4 valence electrons.
Properties of Silicon
• Silicon is an electropositive metalloid element.
• It usually forms compounds in a tetravalent state.
• The melting and boiling points of silicon are 1410 °C and 3265 °C, respectively.
• It forms an important component of ceramics, cement, glass, etc.
• In its purest form silicon is an intrinsic semiconductor.
As per the Bohr model of the atom, the silicon atom consists of 14 electrons, 14 protons, and 14 neutrons.
The atomic number of an atom is also the number of electrons as well as protons present in that atom.
The neutral neutrons and positively charged protons reside inside the nucleus while the negatively charged shells are distributed in different shells around the nucleus.
The shells are the definite paths assigned to each electron in which they revolve around the nucleus. The maximum numbers of electrons that can be housed in a shell are given by the formula 2n2.
The silicon atom consists of 3 shells viz. K, L, and M shell. The K shell houses 2 electrons, the L shell has 8 electrons while the M shell has 4 electrons.
The electrons in the M shell are farthest from the nucleus and are also known as valence electrons. Therefore, silicon has 4 valence electrons.
Related Article: Boron Bohr Model