Now, look at the model again.....Hydrogen's valence electron 'feels' a +1 charge from the nucleus and Helium's
valence electrons 'feels' +2 charge. We would expect Lithium's valence electron to 'feel' +3 charge, but INSTEAD it
'feels' a +1 charge. Propose an explanation for why Lithium's valence electron 'feels' a weaker charge than
expected.