Question

Question #103ea

Answer 1

Electronic Configuration is how we keep track of where the electrons are in an atom.

For example, look at carbon, element 6. You probably already have learned that atoms are arranged by their atomic number and that atomic number is actually the same as the number of protons (each with a +1 charge) in the atom, right? So Carbon, element #6, has 6 protons in the nucleus. That means it has to have 6 negative charges to balance the 6 positive charges. Thus, carbon has 6 electrons.

Those electrons are stored in orbitals, usually in pairs. In the case of carbon, there are two electrons in the 1s orbital, 2 in the 2s orbital, and 2 in the 2p orbitals. We write this as: `1s^2 2s^2 2p^2`. That is the electron configuration of carbon.

Similarly, we can look at element 15, Phosphorous. It has fifteen electrons and thus we fill the orbitals, starting with the lowest energy orbital, 1s: `1s^2 2s^2 2p^6 3s^2 3p^3`

From the electronic configuration of an atom we can determine the number of valence electrons, how many paired and unpaired electrons are present, and how many more electrons are needed to make an inert gas electronic configuration.

Go ahead and try a few on your own. You can find the answers here: electronic configurations of the elements .