Valence Electrons

[Malley Craig 1L]

So the dots surrounding the atoms are valence electrons right? How do you know how many valence electrons surround the atoms?

[206468528]

Yes, the dots in a Lewis structure represent valence electrons. To determine the number of valence electrons for an atom, look at its group number on the periodic table. For example, elements in Group 1 have 1 valence electron, Group 2 has 2, and Groups 13–18 have 3–8 valence electrons, respectively.

[Alyssa Truong 1L]

Yes! The dots surrounding the atoms are valence electrons! You know how many valence electrons surround the atoms by referring to the periodic table. In general it helps to know some rules on how to read the periodic table. For example, I always remember that going from left to right by columns, the valence electron increases. For example, if we look at the second row, starting with the first column, Li, Be, B, C, N, O, F, Ne (with Ne already being the most stable because the octet is full) would accordingly have these numbers of valence electrons: 1, 2, 3, 4, 5, 6, 7, 8. You could also see it backwards if you want to reading the table from right to left, 8, 7, 6, 5, 4, 3, 2, 1.

The number of dots may change though depending on whether or not we change some lone pairs to shared electrons or single/double/triple bonds between atoms in a molecule.