Question

depending on electronic configurations the properties of element vary in different periods and groups explain why ?​

Answer 1

Answer: Elements in the same period have different properties because the number of valence electrons in their outermost shells differ.

In a given column or group, all elements have the same number of electrons in their outermost shells.

For example, in group 2, all elements have two electrons in their outermost shell.

Explanation:

Answer 2

in modern periodic table there are seven horizontal rows called periods.

in a  period, change in valency of an elements varies electronic configuration.

the number of valence electrons is different in these elements. however the number of shells is the same . in a period, the atomic number increases by 1 at a time and the number of valence electrons also increases by one at a time. i a period, there is a gradation in properties of elements.

the elements with the same number of shells occupied by electrons belong to the same period. the elements in the second period namely, Li, Be, B, C, N, O, F and Ne have electrons in the two shells; K, L and M.

the chemical reactivity of an element is determined by the number of valence electrons in it and the shell number of the valence shell. in a period, while going left to right, the atomic number increases by one at a time as a result atomic radius gradually decreases. hence, atomic size decreases.