Question

For main-group elements, are outer electron configurations similar or different within a group? Within a period? Explain.

Answer 1

For main groups elements outer electron configurations is different within a period.

If we see period wise electronic configuration of first periods (H and He) we find different number of outermost shell electrons as follows:

Hydrogen has 1 electron in the 1s level, and to the right, helium, in Group 18, has 2 electrons in the 1s level, a completely filled shell, the duet rule. Helium is the first in the series of noble gases. Moving down to Period 2, lithium is the first element in the row, with a filled 1s configuration. Across the period, first the 2s and then the 2p orbital fill, arriving at the configuration for neon, following the octet rule. Period 3 follows a similar pattern.

For main-group elements, are outer electron configurations similar within a group that elements have same number numbers of electron in the outermost shell.

Similar way if we see group wise electronic configuration of first group elements we find that all elements have same number of outer electronic configuration. That is first group elements like H, Li, Na, K and all have same number of electrons (valance shell electron) in outmost shell that is 1.