Video I took of the gas grill at my house catching on fire! 1  Comedy. 2  Standard YouTube License.
The sodium atom (atomic number 11), with 1 valence electron in its third energy level, would like to achieve the stability of its nearest noble gas neighbor, the neon (Ne) atom (atomic number 10), which contains 8 valence electrons in its second energy level.
There are 7 valence electrons because the highest energy level, 3, has 7 total electrons (5 plus 2 is 7). For calcium, which has an atomic number of 20 and therefore 20 electrons, find calcium on the table (see video).