Question

State reason for the following:
1) The elements of the same group have similar chemical properties
2) The elements of the same period have different properties

Answer 1

a) This is because events of same group have same number of valence electrons in their valence shell. So they would either donate same no. of electrons or would gain same no. of electrons to have a full filled configuration. And since the properties of an element is determined by whether they are electropositive or electronegative they would have similar properties.

b) elements across a period have different number of valence electrons in their valence shell. They would require different no. of electrons to achieve a stable configuration and hence have similar properties