> How many valence electrons does a helium atom have?
The electron configuration of Helium is simply 1s2. We see
that its outermost shell is the s shell and it contains 2 electrons, therefore
the number of valence electrons is also 2.
> What is the formula of the ion formed when potassium
achieves noble-gas electron configuration?
Potassium has a electron configuration of [Ar] 4s1. To
have an electron configuration of only [Ar] which is a noble gas, the one electron
from 4s1 should be removed, hence:
<span>K+</span>
Answer:
Option C = 1.72 mol
Explanation:
Given data:
Mass of KF = 100 g
Moles of KF = ?
Solution:
First of all we have to calculate the molar mass of KF.
Molar mass of KF = 39.0983 g/mol + 18.998403 g/mol
Molar mass of KF = 58. 0967 g/mol
Formula:
Number of moles = mass/molar mass
Number of moles = 100 g/ 58.0967 g/mol
Number of moles = 1.72 mol