Question

use the periodic table to identify the number of core electrons and the number of valence electrons in each case below. potassium (k): 1s²2s²2p⁶3s²3p⁶4s¹ 18 core electrons 1 valence electrons complete iron (fe): ar4s²3d⁶ core electrons valence electrons done

Explanation:

Step1: Understand noble - gas core

The [Ar] in the electron - configuration of iron represents the electron - configuration of argon, which has 18 electrons. The electrons in the noble - gas core are core electrons.

Step2: Count core electrons

Argon has 18 electrons. So, the number of core electrons in iron is 18.

Step3: Identify valence electrons

The valence electrons are in the outermost shell and in the partially - filled d - subshell. For iron with electron - configuration [Ar]4s²3d⁶, the 4s and 3d electrons are valence electrons. The sum of electrons in 4s² and 3d⁶ is 2 + 6=8.

Answer:

core electrons: 18
valence electrons: 8