Question

What is the effective charge felt by an unknown element with 165 protons, 15valence electrons and a charge of +2? (Hint: How many total electrons would theneutral element have? How many electrons does it have given the charge?)

Answer 1

Answer:

$17$

Explanation:

Here, we want to get the effective charge felt by the unknown element

Since the element has a total of 165 protons, the number of electrons in its neutral state is 165 also

Now, having a charge of +2 means it has lost 2 of its electrons, bringing the current total value of electrons to 163

Since there are a total of 163 electrons in the charged state and 15 valence electrons, the number of shielded electrons will be:

$163-15\text{ = 148}$

The effective charge is the difference between the number of protons and the shielding electrons (the electrons not in the valence shell)

Mathematically, we have that as:

$165\text{ - 148 = 17}$