Question

An atom has the following electron configuration. 1s22s22p63s23p64s? How many valence electrons does this atom have? A: 2B: 3C: 5D: 11

Answer 1

2 valence electrons

Explanation:

The electronic configuration is given below as

`1s^22s^22p^62s^23p^64s^2`

Looking at the configuration, you will see that the last energy carries 2 electrons

Hence, the valence electrons are 2