## Homework 2.37 [ENDORSED]

gracehart
Posts: 22
Joined: Sat Jul 09, 2016 3:00 am

### Homework 2.37

2.37: Which of the following statements are true for many-electron atoms? If false, explain why. (a) The effective nuclear charge is independent of the number of electrons present in an atom. (b) Electrons in an s-orbital are more effective than those in other orbitals at shielding other electrons from the nuclear charge because an electron in an s-orbital can penetrate to the nucleus of an atom. (c) Electrons having l=2 are better at shielding than electrons having l=1. (d) Effective nuclear charge for an electron in a p-orbital is lower than for an electron in an s-orbital in the same shell.

Could you explain parts b-d? I understand part a, but am unclear on the other three.

Thanks!

Chem_Mod
Posts: 18878
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 714 times

### Re: Homework 2.37

Hi there!
For others who may be wondering about (a)
(a) False - the effective nuclear charge is affected by the average number of electrons between the nucleus and the electron in question. The effective nuclear charge can roughly be given as Zeff = Z - S

where S is given to be the average number of electrons that are shielding

(b) True, the s orbitals tend to be located closer to the nucleus of an atom than say the p, or d orbitals of the same principle energy level (n = something)

(c) False, electrons having I=2 are located in d orbitals, whereas those in I=1 reside in p orbitals. Electrons of the same principle quantum number ( n ) that are located in p orbitals are going to be located closer to the nucleus and thus have more opportunities for shielding.

(d) True, for the same reason that (c) is false. s orbital electrons of the same shell are located closer to the nucleus and hence have fewer electrons in between them and the nucleus to reduce the effective nuclear charge

Hope this helps!

Helen Shi 1J
Posts: 78
Joined: Sat Jul 22, 2017 3:00 am

### Re: Homework 2.37

Can someone explain how electron shielding works?

Helen Shi 1J
Posts: 78
Joined: Sat Jul 22, 2017 3:00 am

### Re: Homework 2.37

What is the effective nuclear charge?

Courtney Cheney 3E
Posts: 19
Joined: Fri Sep 29, 2017 7:07 am

### Re: Homework 2.37

Can someone explain what the effective nuclear charge is please??? :)

Chem_Mod
Posts: 18878
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 714 times

### Re: Homework 2.37  [ENDORSED]

Effective nuclear charge represents the effective charge of the nucleus after you account for the canceling of charge by the electrons (aka shielding). Electron shielding is when the electron charge balances with the nuclear charge, decreasing the charge that other particles feel. If you think about an atom, the electrons closest to the nucleus will feel the positive charge the most - therefore having the least shield. As you move to the outside of the atom, those electrons have the least amount of shielding because the electrons before them are shielding the majority of the charge.

Dylan Mai 1D
Posts: 70
Joined: Sat Jul 22, 2017 3:00 am

### Re: Homework 2.37

What exactly is Z subscript eff? I read about it in the textbook and still don't understand. Was it covered in lecture? I do not see it in my notes.

Rakhi Ratanjee 1D
Posts: 59
Joined: Fri Sep 29, 2017 7:04 am

### Re: Homework 2.37

Z subscript eff stands for the effective nuclear charge. Effective nuclear charge is related to a reduced electrostatic attraction of outer electrons because of shielding of outer electrons by the electrons that are closer to the nucleus. Effective nuclear charge is affected by how many electrons are in the atom because the more electrons there are, the more shielding will occur, since the electrons will fill more shells, and thus be farther away from the nucleus.