An atom has the electron configuration 1s22s22p63s23p1. how many valence electrons does the atom have? valence electrons

The atom have 3 valence electrons in its valence shell.

Explanation:

Electronic Configuration of give atom is,

1s², 2s², 2p⁶, 3s², 3p¹

As the this atom has three energy levels, i. e. 1, 2 and 3 so the valence energy level or Shell is three. In third shell two electrons are present in s orbital and one electron is present in p orbital. So, in total it has three electrons in valence 3rd shell.

The atom is filled till the third level

the 3rd energy level is therefore the outermost shell

valence electrons are the electrons in the outermost shell

3s² 3p¹

there are 2 electrons in the 3s orbital and one electron in the 3p orbital

therefore altogether the atom has 3 valence electrons