4/11/2016. There's no way I would ever rate a box store 5 stars, but I do like our Home Depot. The service isn't always the greatest, but it's usually pretty decent. The have a wide selection and the prices are generally the best in town.
Electrons with the highest energy levels exist in the outermost shell of an atom and are relatively loosely bound to the atom. This outermost shell is known as the valance shell and electrons in this shell are called valance electrons. A completed outermost shell has valance of zero.
The period of an element can be determined from the element's electron configuration. For example, arsenic, As, has the electron configuration [Ar] 3d104s24p3. The 4 in 4p3 indicates that arsenic's highest occuppied energy level is the fourth energy level. Arsenic is therefore in the fourth period on the periodic table. Basically what ever has the highest number is in the electron configuration, 1. 2. 3. 4, etc., is what row the element is in.