Which of the following has more core electrons than it does valence electrons?
sulfur
carbon
beryllium
oxygen
The correct answer and explanation is:
The correct answer is sulfur.
Sulfur has more core electrons than valence electrons because its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁴. In this configuration, the first two electron shells (1s² and 2s² 2p⁶) represent the core electrons, and the third shell (3s² 3p⁴) represents the valence electrons.
Sulfur has a total of 16 electrons, and 10 of these are in the core shells (1s² 2s² 2p⁶), leaving 6 electrons in the outermost shell (3s² 3p⁴) as valence electrons. So, sulfur has 10 core electrons and 6 valence electrons, making the core electrons more than the valence electrons.
For comparison:
- Carbon (C) has an electron configuration of 1s² 2s² 2p², with 2 core electrons (1s²) and 4 valence electrons (2s² 2p²). The core electrons are fewer than the valence electrons.
- Beryllium (Be) has an electron configuration of 1s² 2s², with 2 core electrons (1s²) and 2 valence electrons (2s²). The core and valence electrons are equal.
- Oxygen (O) has an electron configuration of 1s² 2s² 2p⁴, with 10 core electrons (1s² 2s² 2p⁶) and 6 valence electrons (2p⁴). Similar to sulfur, oxygen has more core electrons than valence electrons.
Therefore, sulfur has the highest number of core electrons compared to its valence electrons.