Question

How many valence electrons are there in Carbon?

Answer 1

Hint: Valence electrons are the total numbers of electrons present in the outermost shell of an atom (i.e. in outermost orbital). The valence electrons for a neutral atom is always definite, it cannot be varied in any condition for a particular atom and may not be equal to its valency.
Most of the time valency varies/changes due to change in oxidation and reduction states.

Complete answer:
First, we need to know that carbon has an atomic number of 6. Or else we can find the atomic number through a periodic table. As its atomic number is 6 means it has 6 protons and for neutral carbon the number of protons is always equal to the number of electrons. Thus carbon has 6 electrons.
Now we know the number of electrons we can find the electronic configuration,
Electronic configuration is the arrangement of electrons on the orbitals. The carbon atom has 6 electrons. The electrons will be placed in different orbitals according to the energy level: $$\left[1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p,7s,5f\right]$$.Now, carbon electron configuration $C(6)=1s^2,2s^2,2p^2$.
After finding the electronic configuration it’s time to determine the valence shell of Carbon.
As we know, the valence shell of an atom can be found from the highest number of principal quantum shell of an atom are called valence electrons, and there are total of four electrons present in valence shell of carbon$$(2s_2,2p_2)$$. Thus, carbon has four valence electrons.

Note:
Carbon has both $+4$ and $-4$. If it loses three electrons to reach a stable state its valency will be $+4$. But if it gains five electrons to reach a stable state its valency will be $-4$. For example in $C{O}_2$, the oxidation state of carbon is $+4$ while in $C{H}_4$, the oxidation state is $-4$. A carbon atom can form four covalent bonds in chemical bonding and that is what valency is.