Effective Nuclear Charge

Effective Nuclear Charge (Zeff) measures the force exerted onto an electron by the nucleus. 

Effective Nuclear Charge & Slater's Rules

Within any given atom there are electrons that experience both attractive and repulsive forces. 

Concept: Using Slater’s Rules calculate the effective nuclear charge of a 3p electron in argon.  

5m

Concept: Using Slater’s Rules calculate the effective nuclear charge of the 4s electron in potassium.  

4m

Concept: Using Slater’s Rules calculate the effective nuclear charge of a 3d electron in bromine.  

4m

Effective Nuclear Charge Additional Practice Problems

Arrange the following atoms according to decreasing effective nuclear charge experienced by their valence electrons S, Al, Si, Mg

a. S > Al > Si > Mg 

b. Mg > Al > Si > S

c. Al > S > Si> Mg 

d. S > Si > Al > Mg

e. Si > Al > Mg > S

Watch Solution

In which orbital does an electron in a phosphorus atom experience the greatest shielding _____?

a) 3p

b) 3s

c) 2p

d) 2s

e) 1s

Watch Solution

Screening by the valence electrons in atom is ______.

a) responsible for a general increase in atomic radius going across a period.

b) less efficient than that by core electrons

c) essentially identical to that by core electrons

d) more efficient than that by core electrons 

e) both more efficient than that by core electrons  and responsible for a general increase in atomic radius going across a period

Watch Solution

Electrons in the 1s subshell are much closer to the molecules in Ar than in He due to the larger ______ in Ar.

a) azimuthal quantum number

b) paramagnetism

c) magnetic quantum numbers

d) Hund's rule 

e) nuclear charge

Watch Solution

What factor best explains the reduction in the effective nuclear charge (Z eff) experienced by the outermost electrons of a multi-electron atom?

 

(a) Orbital splitting by the increased nuclear charge.

(b) The outermost electrons are moving too quickly to feel the full pull of the nucleus.

(c) Hund’s rule.

(d) The inner electrons shield the outer electrons from the nuclear charge.

(e) Pauli’s exclusion principle.

Watch Solution

Which of the following statements is TRUE?

 

A. An orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy. 

B. An orbital that penetrates into the region occupied by core electrons is more shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy.

C. It is possible for two electrons in the same atom to have identical values for all four quantum numbers.

D. Two electrons in the same orbital can have the same spin.

E. None of the above are true.

Watch Solution

Choose the statement that is TRUE.

 

a) Outer electrons efficiently shield one another from nuclear charge.

b) Core electrons effectively shield outer electrons from nuclear charge.

c) Valence electrons are most difficult of all electrons to remove.

d) Core electrons are the easiest of all electrons to remove.

e) All of the above are true

Watch Solution