Write the expected electron configurations for each of the following atoms: Cl, As, Sr, W, Pb, Na+, I-, Mg 2+, S2-, and Cf.?

Answer 1

You can look all of these up for yourself here:

https://ptable.com/?lang=en#Properties

Answer 2

I'm certainly not going to do all of them, but here are a few to get you started and hopefully you can do the rest.

Cl (17 electrons):  1s2 2s2 2p6 3s2 3p5

Na+ (Na lost 1 e- so has 10 electrons):  1s2 2s2 2p6 3s1

I- (I gained 1 e- so has 54 electrons): [Kr]5s2 4d10 5p6