Question

How many valence electrons are in carbon?

Answer 1

Hint The atomic number of C is 6 and hence have 6 protons, 6 electrons and 6 neutrons. The C is placed with group 14 and in the second period.

Complete answer:
We are very familiar with the C atom, from the time we are studying about the chemical compounds. As for many compounds C is the central atom and we study the compounds formed by C atoms as a special branch of chemistry i.e. organic chemistry. In organic chemistry we study millions of hydrocarbons i.e. the compounds formed by the combination of C and H atoms. And this combination capability of the C is due to its valency or the number of valence electrons present in the atom.
Now let's consider what valence electrons are then the atomic number of C, the position of C in periodic table and find the total number of valence electrons present in C atom.
Valence electrons are those electrons which enter the outermost shell of the atom and actively take part in the chemical combinations.
We know that the atomic number of C is 6 and hence the number of electrons present in C atom is 6. And now let's check on the position of C in the periodic table.The carbon is placed in group -14 elements and it is arranged in the second period of the periodic table.
While studying about the periodic table we always note a fact that in a group, all the elements will have the same number of valence electrons and as we move down the group new shells aer introduced.The period to which an element belongs to represents the outermost shell of the element.
Since the C atom belongs to the second period,the C will have two shells and the second shell will be the outermost shell.
Now we know the outermost shell now we have to distribute the electrons in various shell
We know that the first shell,K shell, could only accommodate electrons, then the next shell-L shell will accommodate 8 electrons ,the third shell M shell accommodates electrons and so on. There are 6 electrons in the C atom,when we distribute the six electrons along the shells , K shell will have 2 electrons and the remaining four electrons are occupied by the second shell, the L shell.

Hence the C will have a valency of 4 and is called a tetravalent atom i.e. it could extend its valency upto 4 and can form 4 bonds with other atoms.

Note:
Alternate method: Another direct method to find the number of electrons in the valence shell if we know the orbital arrangement in the shells in increasing order is to simply write the electronic configuration and add up the electrons present in various orbitals in a shell which gives the total valence electrons of the atom. The electronic configuration of C is $1s^{2}2s^{2}2p^2$. The outermost shell is having the n (Principal quantum number or shell number) value 2,hence the total number of electrons in different orbitals of second shell will be the total valence electrons present in an atom.For carbon the total number of electrons in the outermost shell is 4.