Q: Which of the following best describes the trend in electron affinity across a period?

Electron affinity becomes more negative from left to right

Q: When forming a cation from a transition metal, which electrons are removed first?

Electrons from the highest principal quantum number $n$ (usually $s$ orbital)

Q: Which of the following is a correct statement about penetration and shielding?

Electrons in orbitals with greater penetration experience less shielding and higher $Z_{\mathrm{eff}}$

Question 1

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number $\ell$

Question 2

According to the Pauli exclusion principle, which of the following is true for electrons in the same orbital?

Accepted Answer

They must have opposite spins ($m_s = +1/2$ and $m_s = -1/2$)

Question 3

Which electron configuration represents the ground state of oxygen?

Accepted Answer

$1s^2\ 2s^2\ 2p^4$

Question 4

Which of the following best explains why the $3p$ sublevel is higher in energy than the $3s$ sublevel in multi-electron atoms?

Accepted Answer

Electron-electron repulsion and shielding effects

Question 5

Which of the following ions has the largest ionic radius?

Accepted Answer

$\mathrm{Cl^-}$

Question 6

What is the electron configuration for $\mathrm{Fe^{2+}}$?

Accepted Answer

$[\mathrm{Ar}]\ 3d^6$

Question 7

Which element has the highest first ionization energy?

Accepted Answer

Neon ($\mathrm{Ne}$)

Question 8

Which of the following statements about atomic radius is correct?

Accepted Answer

Atomic radius decreases from left to right across a period

Question 9

Which of the following elements is most likely to be paramagnetic?

Accepted Answer

Nitrogen ($\mathrm{N}$)

Question 10

What is the effective nuclear charge ($Z_{\mathrm{eff}}$) experienced by a valence electron in a main group atom as you move from left to right across a period?

Accepted Answer

$Z_{\mathrm{eff}}$ increases

Question 11

Which of the following electron configurations represents a transition metal in its ground state?

Accepted Answer

$[\mathrm{Ar}]\ 4s^2\ 3d^6$

Question 12

Which of the following is the correct order of sublevel energies in a multi-electron atom?

Accepted Answer

$3s < 3p < 3d < 4s$

Question 13

Which of the following elements has the greatest metallic character?

Accepted Answer

Cesium ($\mathrm{Cs}$)

Question 14

What is the electron configuration for the $\mathrm{Cu^+}$ ion?

Accepted Answer

$[\mathrm{Ar}]\ 3d^{10}$

Question 15

Which of the following best describes the trend in electron affinity across a period?

Accepted Answer

Electron affinity becomes more negative from left to right

Question 16

Which quantum numbers are needed to uniquely identify an electron in an atom?

Accepted Answer

$n,\ \ell,\ m_\ell,\ m_s$

Question 17

Which of the following elements has the smallest atomic radius?

Accepted Answer

Fluorine ($\mathrm{F}$)

Question 18

When forming a cation from a transition metal, which electrons are removed first?

Accepted Answer

Electrons from the highest principal quantum number $n$ (usually $s$ orbital)

Question 19

Which of the following is a correct statement about penetration and shielding?

Accepted Answer

Electrons in orbitals with greater penetration experience less shielding and higher $Z_{\mathrm{eff}}$

Question 20

Which of the following elements is most likely to form a diamagnetic ion?

Accepted Answer

Zinc ($\mathrm{Zn^{2+}}$)

Periodic Properties of the Elements (Chapter 9): Quantum Numbers, Energy Levels, and Electron Configurations

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