Question

Consider the element silicon, Si. (a) Write its electron configuration. (b) How many valence electrons does a silicon atom have? (c) Which subshells hold the valence electrons?

Short answer

(a) The electron configuration of silicon (Si) is 1s² 2s² 2p⁶ 3s² 3p². (b) Silicon has 4 valence electrons. (c) The subshells holding the valence electrons are 3s and 3p.

Step-by-step solution

(a) Electron Configuration of Silicon (Si)

To write the electron configuration of silicon, we should know its atomic number, which is 14 (it has 14 protons and 14 electrons). Using the periodic table, we follow the order of the subshells (s, p, d, f) as we fill the electrons to reach the atomic number 14. The electron configuration is as follows: 1s² 2s² 2p⁶ 3s² 3p²

(b) Number of Valence Electrons

Valence electrons are the electrons present in the outermost energy level of an atom. For silicon, if we look at its electron configuration (1s² 2s² 2p⁶ 3s² 3p²), we observe that the outermost energy level is 3, and it has 2 electrons in the 3s subshell and 2 electrons in the 3p subshell. So, the total number of valence electrons for silicon is: 2 + 2 = 4 valence electrons

(c) Subshells Holding Valence Electrons

As we determined in part (b), the valence electrons are in the outermost energy level, which for silicon is energy level 3 (n=3). Looking at the electron configuration, we can identify the subshells holding valence electrons in this energy level: 3s² 3p² So, the subshells holding the valence electrons for silicon are 3s and 3p.