periodic table. the atomic number of an element is 15. what is the likely arrangement of the valence and…

periodic table. the atomic number of an element is 15. what is the likely arrangement of the valence and core electrons in a neutral atom of this element? a. there are 3 valence electrons and 12 core electrons. b. there are 4 valence electrons and 11 core electrons. c. there are 5 valence electrons and 10 core electrons. d. there are 6 valence electrons and 9 core electrons.

periodic table. the atomic number of an element is 15. what is the likely arrangement of the valence and core electrons in a neutral atom of this element? a. there are 3 valence electrons and 12 core electrons. b. there are 4 valence electrons and 11 core electrons. c. there are 5 valence electrons and 10 core electrons. d. there are 6 valence electrons and 9 core electrons.

Answer

Explanation:

Step1: Recall electron - configuration concept

The atomic number of an element is equal to the number of electrons in a neutral atom. For an element with atomic number (Z = 15), the electron - configuration is (1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}).

Step2: Distinguish between core and valence electrons

Core electrons are the electrons in the inner shells, and valence electrons are in the outermost shell. The first - two shells ((n = 1) and (n=2)) are filled: (1s^{2}2s^{2}2p^{6}), which gives (2 + 2+6=10) core electrons. The electrons in the (n = 3) shell ((3s^{2}3p^{3})) are valence electrons, and there are (2 + 3=5) valence electrons.

Answer:

C. There are 5 valence electrons and 10 core electrons.