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If your periodic table has the old-style numbering (1A, 2A, etc), what's the easiest way to tell how many valence electrons an element has?
A. The number of valence electrons is the same as the column number.
B. You must write out the entire electron configuration.
C. The number of valence electrons is the same as the period number.

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randomsheila
A. The number of valence electrons is the same as the column number

For example, all the elements in group 1 (H, Na, K, Rb, Cs and Fr) all have 1 valence electron. The same happens with all group 2 elements. Groups 3-12 (the transition metals) have 2 valence electrons as well, because their electron shells are filled with the highest amount of electrons possible. Group 13 elements would have 3 valence electrons, group 14 elements would have 4 valence electrons and so on.