How does the Number of valence electron and valency vary from left to right in second period of periodic table
Answers
Number of valence electrons +1 to +3 and then -3 to -1 and 0 vary from left to right in the second period of periodic table. From left to right electronegativity increases.
Electronegativity is a tendency of an atom to attract and form bonds with electrons. Most of atoms follow octet rule (tendency to have 8 electron in outer shell to finish octet). From left to right most of elements have less than half full valance shell and significantly higher energy is required to gain the electron as compare to losing the electron. Elements with more than half full valance shell are easily able to get an electron as compared to lose. Due to this reason elements from left side are easier to lose electron to form bonds while elements from right side are more efficient in getting the electron to finish the octet in outer shell.