Question

please help me.. . . . . .
n o s p a m .... please

Answer 1

Answer:

1. While going from left to right within a period the outermost shell remains the same. However, the positive charge on the nucleus goes on decreasing and thus the effective nuclear charge goes on increasing. As a result of this the tendancy of atom to lose valence electrons decreases with a period from left to right.

2. While going down a group a new shell is added therefore the distance between the outermost electron and the nucleus goes on increasing as a result of this the atomic size increases in spite of the increased nuclear charge. Therefore atomic radius goes on increasing down a group.

3. All the elements in a group have the same no. of valence electrons. Therefore elements in the same group should have same valency. For example, the elements of Group one contain only one valence electron; the valency of element of group one is one. Similarly for group two, the valency is two.

4. The no. of elements present in third period is decided on the basis of electronic configuration and octet rule. Argon is the last element of the third period and has the capacity of 18 electrons. It's octet of electron is completed and as argon belongs to zero group, the third shell contains 18 electrons.