Which element has
(a) two shells, both of which are completely filled with electrons?
(b) the electronic configuration 2, 8, 2?
(c) a total of three shells, with four electrons in its valence shell?
(d) a total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?
(a) Neon has two shells, both of which are completely filled with electrons (K shell with 2 electrons and L shell with 8 electrons).
(b) Magnesium has the electronic configuration 2, 8, 2.
(c) Silicon has a total of three shells, with four electrons in its valence shell (K shell with 2 electrons, L shell with 8 electrons and M shell with 4 electrons.)
(d) Boron has a total of two shells, with three electrons in its valence shell (K shell with 2 electrons and L shell with 3 electrons).
(e) Carbon has twice as many electrons in its second shell as in its first shell (K shell with 2 electrons and L shell with 4 electrons).
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