**Part A: Calculate for a valence electron in an oxygen atom.**

**Part B: Calculate for the 4s electron in a copper atom, m Cu.**

**Part C: Calculate for a 3d electron in a copper atom, m Cu.**

**Answer:**

Calculate the as follows:

here, Z is atomic number and ‘s’ is shielding constant.

Rules calculating the shielding constant:

step-I:

write the electronic configuration like shown below.

step-2:

If we want to calculate the shielding constant for 2p, then the electrons the right Side of 2p is zero

(i.e. no shielding contribution)

step-3:

If the group is ‘s’ or ‘p’ then the amount 0.35 for each electron in n shell, 0.85 for each electron in (n-l) shell, for an electron in (n-2) shell.

If the group is ‘d’ or f ’ then the amount 0.35 for each electron in n shell, and 1.00 for the remaining electron on left side.