3 years ago
Last edited at 12:21PM on 12/7/2010
Thankfully, elements are grouped on the periodic table according to the number of valence electrons. So with a periodic table in front of you, determine whether an element is a transition metal or not. Transition metals are those in columns 3-12. Non-transition pertain to columns: 1, 2, 13, 14, 15, 16, 17, 18
Take potassium(K) as an example. Since potassium is not in the transition group(it's in the Alkali group), look to the column number. The column number translates into the number of valence electrons for all non-transition metals. Potassium and the elements of the Alkali column (and hydrogen: not in the alkali group but still abiding this rule) all have 1 valence electron.
For groups 13-18 subtract 10 from the group number to find the number of valence electrons for a given element. Take argon(Ar) in group/column 18. An argon atom would have 8 valence electrons just like the other noble gases in group 18.
Groups 3-12, the transition metals, are different. They all have 2 valence electrons.
Lanthanides and Actinides (rows starting with La and Ac, the bottom groups of the periodic table) also all have 2 electrons in their outer shell.