What is the electron configuration of oxide ion (-2)?
Oxide ion is the same electron configuration as the element two electrons above that. You should organize electronic configurations by looking at the periodic table. The two far left columns represent the “s” orbitals, the six far right columns are the “p” orbitals, and the ones in the middle are the “d” shell orbitals. (The detatched rows at the bottom of the periodic table represent the “f” shell.) So, if we count by rows and columns, we can always figure out an electronic configuration. Look at helium. It’s got two electrons, which is the maximum amount an s orbital has, and it’s in the first row. So its 1(row)s(column location)2(two electrons in that shell. Now look at lithium (Li). It not only has the electrons from that row, but also the rows underneath it. Lithium has 1s2 (for the two electrons in row 1) and 2s1 (2 for the row, s for the column, and 1 electron). Now look at regular oxygen. It has the first row (1s2), and it’s already filled up the 2s shell to get a 2s2. Oxygen i
