A question asks:

This question refers to isolated gaseous atoms. In which atom are all electrons paired? Ba, Br, S or Si?

I thought it was Ba as its electron configuration is [Xe] 6s2.

However, the answer says Si, which seems incorrect to me.

Could someone please confirm the answer for me?


  • 5
    $\begingroup$ Si seems incorrect to me as well. $\endgroup$ Feb 23 '20 at 7:15

The configuration for the free atoms is:

  • Ba - $\mathrm{[Xe]\ 6s^2}$
  • Br - $\mathrm{[Ar]\ 3d^{10} 4s^2 4p^5}$
  • S - $\mathrm{[Ne]\ 3s^2 3p^4}$
  • Si - $\mathrm{[Ne]\ 3s^2 3p^2}$


  • Barium has no unpaired electrons.
  • Bromine has one unpaired electron in 4p subshell.
  • Sulfur has two unpaired electrons in the 3p subshell.
  • Silicon has two unpaired electrons in the 3p subshell.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.