Q: Which of the following best explains why atomic radius decreases across a period from left to right in the periodic table?

The effective nuclear charge ($Z_{\text{eff}}$) increases, pulling electrons closer to the nucleus.

Q: Which of the following statements about effective nuclear charge ($Z_{\text{eff}}$) is correct?

$Z_{\text{eff}}$ increases across a period because the number of protons increases while shielding remains relatively constant.

Q: Which of the following correctly predicts the order of increasing atomic radius for the elements lithium ($\mathrm{Li}$), sodium ($\mathrm{Na}$), and potassium ($\mathrm{K}$)?

$\mathrm{Li} < \mathrm{Na} < \mathrm{K}$

Q: Which of the following best explains why noble gases are generally unreactive?

They have completely filled valence shells.

Q: Which of the following best explains why the first ionization energy of magnesium ($\mathrm{Mg}$) is higher than that of sodium ($\mathrm{Na}$)?

Magnesium has a higher effective nuclear charge.

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

Electron affinity becomes more negative.

Q: Which of the following best explains why transition metals often have multiple possible oxidation states?

They have incomplete $d$ subshells that can lose different numbers of electrons.

Question 1

Which of the following best explains why atomic radius decreases across a period from left to right in the periodic table?

Accepted Answer

The effective nuclear charge ($Z_{	ext{eff}}$) increases, pulling electrons closer to the nucleus.

Question 2

Which element is most likely to form a $+2$ ion based on its position in the periodic table?

Accepted Answer

Magnesium ($\mathrm{Mg}$)

Question 3

Which of the following pairs of elements are both considered transition metals?

Accepted Answer

Copper ($\mathrm{Cu}$) and Zinc ($\mathrm{Zn}$)

Question 4

Which of the following correctly describes the trend in first ionization energy as you move down a group in the periodic table?

Accepted Answer

It decreases because electrons are farther from the nucleus and more shielded.

Question 5

Which of the following elements is expected to have the highest second ionization energy?

Accepted Answer

Sodium ($\mathrm{Na}$)

Question 6

Which of the following best explains why fluorine ($\mathrm{F}$) is more electronegative than chlorine ($\mathrm{Cl}$)?

Accepted Answer

Fluorine has a smaller atomic radius and greater effective nuclear charge.

Question 7

Which of the following ions is isoelectronic with neon ($\mathrm{Ne}$)?

Accepted Answer

$\mathrm{Na^+}$

Question 8

Which of the following statements about effective nuclear charge ($Z_{	ext{eff}}$) is correct?

Accepted Answer

$Z_{	ext{eff}}$ increases across a period because the number of protons increases while shielding remains relatively constant.

Question 9

Which of the following elements is most likely to be found as a diatomic molecule in its elemental form?

Accepted Answer

Oxygen ($\mathrm{O}_2$)

Question 10

Which of the following best describes the electron configuration of a transition metal ion with an anomalous electron configuration, such as copper ($\mathrm{Cu}$)?

Accepted Answer

$[\mathrm{Ar}]\ 4s^1\ 3d^{10}$

Question 11

Which of the following correctly predicts the order of increasing atomic radius for the elements lithium ($\mathrm{Li}$), sodium ($\mathrm{Na}$), and potassium ($\mathrm{K}$)?

Accepted Answer

$\mathrm{Li} < \mathrm{Na} < \mathrm{K}$

Question 12

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have completely filled valence shells.

Question 13

Which of the following elements is a member of the alkaline earth metals family?

Accepted Answer

Calcium ($\mathrm{Ca}$)

Question 14

Which of the following correctly describes the trend in metallic character across a period from left to right?

Accepted Answer

Metallic character decreases.

Question 15

Which of the following best explains why the first ionization energy of magnesium ($\mathrm{Mg}$) is higher than that of sodium ($\mathrm{Na}$)?

Accepted Answer

Magnesium has a higher effective nuclear charge.

Question 16

Which of the following elements is most likely to form an anion with a $-2$ charge?

Accepted Answer

Oxygen ($\mathrm{O}$)

Question 17

Which of the following best describes the trend in electron affinity across a period from left to right?

Accepted Answer

Electron affinity becomes more negative.

Question 18

Which of the following elements is most likely to be found in nature as a free metal due to its low reactivity?

Accepted Answer

Gold ($\mathrm{Au}$)

Question 19

Which of the following best explains why transition metals often have multiple possible oxidation states?

Accepted Answer

They have incomplete $d$ subshells that can lose different numbers of electrons.

Question 20

Which of the following correctly predicts the order of increasing first ionization energy for the elements potassium ($\mathrm{K}$), calcium ($\mathrm{Ca}$), and scandium ($\mathrm{Sc}$)?

Accepted Answer

$\mathrm{K} < \mathrm{Ca} < \mathrm{Sc}$

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