Question

Name the element that corresponds to the following electron configuration.

1s^2, 2s^2, 2p^1

boron
neon
lithium
helium

Answer 1

You sum up the electrons in the given configuration, in this case 5. Atoms are electroneutral, therefore electrons and protons have to be the same number. So, we need the element which is number 5. A quick look at the periodic system gives Boron.

Another way to solve the problem - there are three electrons in the second electron shell, as the configuration suggests. This means that our element should be found in period two, group three of the periodic system. Again, a quick look at it - gives Boron.

It's a chemistry question, btw.

Answer 2

Thank you for explaining all that to me it really helped!