Group the following electron configurations in pairs that would represent similar chemical properties of their atoms: (a) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2}\) (b) \(1 s^{2} 2 s^{2} 2 p^{3}\) (c) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{10} 4 p^{6}\) (d) \(1 s^{2} 2 s^{2}\) (e) \(1 s^{2} 2 s^{2} 2 p^{6}\) (f) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{3}\)

For each electron configuration, look at the highest energy level (The biggest number in the configuration) and count the total number of electrons at that energy level. (a) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2}\) - Valence electrons: 8 (2 s electrons & 6 p electrons in shell 3)(b) \(1 s^{2} 2 s^{2} 2 p^{3}\) - Valence electrons: 5 (2 s electrons & 3 p electrons in shell 2)(c) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{10} 4 p^{6}\) - Valence electrons: 8 (2 s electrons & 6 p electrons in shell 4)(d) \(1 s^{2} 2 s^{2}\) - Valence electrons: 2 (2 s electrons in shell 2)(e) \(1 s^{2} 2 s^{2} 2 p^{6}\) - Valence electrons: 8 (2 s electrons & 6 p electrons in shell 2)(f) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{3}\) - Valence electrons: 5 (2 s electrons & 3 p electrons in shell 3)

Now group the electron configurations that share same number of valence electrons together as they represent similar chemical properties of atoms. Pair 1: (a) & (c) - Both have 8 valence electronsPair 2: (b) & (f) - Both have 5 valence electronsPair 3: (d) cannot be paired because it has 2 valence electrons which is unique among the given configurations. Pair 4: (e) cannot be paired because even though it has 8 valence electrons like (a) and (c), it has them in energy level 2 as opposed to energy level 3 for (a) and energy level 4 for (c)