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: Effective Nuclear Charge

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Concept: Effective Nuclear Charge

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Concept: Effective Nuclear Charge

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Concept: Effective Nuclear Charge

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

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

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

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Effective Nuclear Charge Additional Practice Problems

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

a. 2p

b. 2s

c. 3p

d. 3s

e. 1s 

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The effective nuclear charge for an atom is less than the actual nuclear charge due to ________.

a. shielding
b. paramagnetism
c. electron-pair repulsion
d. penetration
e. relativity

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Determine the effective nuclear charge Zeff for a 4f electron in Ce, Pr, and Nd. There is a decrease in size, commonly known as the lanthanide contraction, with increasing atomic number in the lanthanides. Report the sizes of these atoms. 

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Classify each statement about effective nuclear charge, Z eff, as true or false.

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Classify each statement about effective nuclear charge, Zeff, as true or false.

1. A 1s electron in a B atom has a smaller Zeff than a 1s electron in a Be atom.

2. Effective nuclear charge does not depend on the number of electrons present in an atom.

3. Across a period, as Zeff increases, atomic size increases.

4. Effective nuclear charge increases from left to right across a period on the periodic table.

5. In a Be atom, 1s electron has a greater Zeff than a 2s electron.

6. Electrons in an s orbital are more effective than those in other orbitals at shielding other elctrons from nuclear charge.

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Calculate Zeff for the 4s electron in a copper atom, Cu and then Calculate  Zeff for a 3d electron in a copper atom, Cu.

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Rank the following elements by effective nuclear charge,Z eff, for a valence electron from highest to lowest Zeff:

Po, Rn, Ba, Bi, Pb (same as ionization energy)

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Rank the following elements by effective nuclear charge, Z eff, for a valence electron.

Kr, Se, Ca, K, Ge

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Calculate Zeff for the 4s electron in a copper atom, Cu. Express your answer numerically.

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The radii of the ions in this series decrease because

a) the elements are in the same period.

b) the effective nuclear charge is increasing.

c) the atomic radius of Na decreases  from Na to Al.

d) the first ionization energies increase from Na to Al.

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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

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In which orbital does an electron in a phosphorus atom experience the greatest effective nuclear charge?

a) 1s

b) 2s

c) 2p

d) 3s

e) 3p

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

a) 3p

b) 3s

c) 2p

d) 2s

e) 1s

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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

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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

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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.

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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.

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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

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