Question

an atomic anion with a charge of - 2 has the following electron configuration: he 2s²2p⁶. what is the chemical symbol for the ion? how many electrons does the ion have? how many 2s electrons are in the ion?

Explanation:

Step1: Determine number of electrons in [He] configuration

Helium ([He]) has 2 electrons.

Step2: Determine number of electrons in 2s and 2p sub - shells

The 2s sub - shell has 2 electrons and the 2p sub - shell has 6 electrons. So in total, the electrons from 2s and 2p are \(2 + 6=8\) electrons.

Step3: Calculate total number of electrons in the ion

The total number of electrons in the ion is \(2 + 8=10\) electrons.

Step4: Find the neutral atom's electron number

Since the ion has a charge of - 2, the neutral atom has \(10-2 = 8\) electrons. The element with 8 electrons in its neutral state is oxygen. The ion is \(O^{2 -}\).

Step5: Identify number of 2s electrons

From the electron - configuration \([He]2s^{2}2p^{6}\), the number of 2s electrons is 2.

Answer:

What is the chemical symbol for the ion? \(O^{2 -}\)
How many electrons does the ion have? 10
How many 2s electrons are in the ion? 2