Electron Configuration

[Viviana Velasquez]

Can somebody break down how to figure out electron configuration?

[chrisleung-2J]

You can determine electron configuration based on the position of the element in question on the periodic table. The period (horizontal row) indicates the principal energy level of the valence electrons for that element, and the groups (vertical columns) reveal the sublevel in which the valence electrons can be found. For example, the element Bromine is found in the 4th period and 17th group. Because it is in the 4th period, we know that the valence electrons will be found in the 4th principal level. Since Br is in Group 17, we also know that the final valence electron will be found in the p-sublevel (reference this: https://archives.library.illinois.edu/e ... tx55p2.GIF). We can then write the condensed electron configuration for Br by starting with the noble gas which precedes it, Ar, and following it with the electrons that occur after it. Consequently, the final answer would be [Ar]3d¹⁰4s²4p⁵. A trick is that the total number of electrons in the electron configuration for a neutral atom will equal the number of protons in the atom; In this case, we have 18 e- (from Ar) + 10 + 2 + 5 = 35.