Silicon, a chemicalelement with the symbol Si and atomic number 14, is a crystalline solid with ablue-grey metallic luster. According to the Pauli scale, its electronegativityvalue is 1.90 and it can show characteristics of both metals and non-metals(metalloid). Its oxides show an amphoteric nature as its oxidation statesexhibit -4, -3, -2, -1, 0, +1, +2, +3, +4.

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Silicon with 96.5% -99.5% purity can be made by reducing quartzite or sand with highly purifiedcoke. The reduction process takes place in presence of excess SiO2 whichhelps to stop the production of silicon carbide (SiC).

SiO2+ 2 C → Si + 2 CO2 SiC + SiO2→ 3 Si + 2 CO

You are here toknow valence electrons of the silicon atom, aren’t you? Don’t worry along with siliconvalence 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 arealways definite, it cannot be varied (more or less) in any condition for aparticular atom 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.

### Silicon (Si)Valence Electrons

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

Step 1: Find theAtomic Number

To find out theatomic number of silicon, we can use the periodic table. With the help of theperiodic table, we can easily see that the atomic number of silicon is 14. Asits atomic number is 14, it has 14 protons, and for neutral silicon, the numberof protons are always equal to the number of electrons i.e. has 14 electrons inits nucleus.

Step 2: WriteElectron Configuration

Electronconfiguration is the arrangement of electrons on the orbitals. The silicon atomhas a total of 14 electrons so, we have to put 14 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,

Silicon electronconfiguration Si (14) =1s22s22p63s23p2(completeconfiguration).

= 3s²3p²(condensed configuration).

Step 3: 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 3s²3p², thehighest value of n is 3 so that the valence shell of silicon is3s²3p².

Step 4: FindValence Electrons

The total number ofelectrons present in the valence shell of an atom are called valence electrons,and there are a total of four electrons present in the valence shell of silicon(3s²3p²). Thus,silicon has four valence electrons.

### Valency of Silicon(Si)

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 siliconcan reach the stable state (nearest inert gas configuration) either by losing 4outermost electrons or by gaining 4 electrons.So that the valency of siliconis 4 (tetravalency).

Note: Silicon hasboth +4 & -4 valency states. If it loses three electrons to reach a stablestate (i.e. He), its valency will be +4. But if it gains five electrons toreach a stable state (i.e. Ne), its valency will be -4 as explained above.

In another sense, asilicon atom can form four covalent bonds in chemical bonding (For example SiF4,SiH4, SiCl4, etc.), and that what valency is, the maximum ability to form bondswith different atoms at the time of chemical reactions.

We can also find the valency of silicon with thehelp of the periodic table. As silicon belongs to group 14 (IVa) along with carbon(C), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). All these elementshave a valency state of four (tetravalent).