(1) In a period, change in valency of an element varies electronic configuration. The number of valence electrons is different in these elements. However, the number of shells is the same.
(2) In a period, while going from left to right, the atomic number increases by one at a time and the number of valence electrons also increases by one at a time.
(3) In periods 2 and 3, while going from left to right, valency varies.
| Elements |
Li |
Be |
B |
C |
N |
O |
F |
Ne |
| Valancy |
1 |
2 |
3 |
4 |
3 |
2 |
1 |
0 |
| Elements |
Na |
Mg |
Al |
Si |
P |
S |
Cl |
Ar |
| Valancy |
1 |
2 |
3 |
4 |
3 |
2 |
1 |
0 |
