Use the periodic table to identify the number of core electrons and the number of valence electrons in each case below.
Potassium (K): 1s22s22p63s23p64s1
18 core electrons
1 valence electrons
Iron (Fe): [Ar]4s23d6
18 core electrons
8 valence electrons
Argon (Ar): [Ne]3s23p6
10 core electrons
8 valence electrons
Magnesium (Mg): 1s22s22p63s2
10 core electrons
2 valence electrons
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