$$\text{Mg}(g) \rightarrow \text{Mg}^{2+}(g) + 2e^-$$

Question 1

Which of the following statements best describes the concept of effective nuclear charge ($$Z_{	ext{eff}}) in a $$many-electron atom?

Accepted Answer

It is the charge experienced by an electron after accounting for shielding by other electrons, calculated as $$Z_{	ext{eff}} = Z - S.$$

Question 2

Which of the following atoms has the largest atomic radius: Be, Mg, Ca, or Sr?

Accepted Answer

Sr

Question 3

Which of the following atoms has the largest atomic radius: K, V, As, or Br?

Accepted Answer

K

Question 4

Which of the following elements has the highest first ionization energy: Be, Mg, Ca, or Sr?

Accepted Answer

Be

Question 5

Which of the following elements has the highest first ionization energy: K, V, As, or Br?

Accepted Answer

Br

Question 6

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

Accepted Answer

From the orbitals with the highest principal quantum number ($$n)$$

Question 7

What is the electron configuration for $$	ext{Na}^+$$?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 8

Which of the following ions has the largest ionic radius: $$	ext{Na}^+$$, $$	ext{Mg}^{2+}$$, $$	ext{F}^-$$, or $$	ext{O}^{2-}$$?

Accepted Answer

$$	ext{O}^{2-}$$

Question 9

Which process is represented by the equation $$	ext{Na}^+(g) ightarrow 	ext{Na}^{2+}(g) + e^-$$?

Accepted Answer

Second ionization energy

Question 10

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity is the energy change when an electron is added to a gaseous atom, and for most nonmetals (except group 8A), energy is released.

Question 11

Which of the following ions has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$?

Accepted Answer

$$	ext{S}^{2-}$$

Question 12

A hospital uses sodium metal in a chemical reaction. Which property makes sodium easy to handle in terms of electron removal?

Accepted Answer

Sodium has a low first ionization energy, making electron removal easy.

Question 13

Which of the following best explains why atomic radius increases down a group in the periodic table?

Accepted Answer

Additional electron shells are added, increasing the distance between the nucleus and the outermost electrons.

Question 14

Which of the following best explains why first ionization energy increases across a period?

Accepted Answer

Effective nuclear charge increases, making electrons harder to remove.

Question 15

A chemist is comparing the electron affinity of chlorine and argon. Which statement is correct?

Accepted Answer

Chlorine releases energy when gaining an electron, while argon does not.

Question 16

Which of the following ions is isoelectronic with $$	ext{Ar}$$?

Accepted Answer

$$	ext{S}^{2-}$$

Question 17

Which of the following best describes the trend in ionic radii for cations compared to their parent atoms?

Accepted Answer

Cations are smaller than their parent atoms because they lose electrons.

Question 18

A scientist needs to remove two electrons from a magnesium atom in the gas phase. Which equation represents this process?

Accepted Answer

$$	ext{Mg}(g) ightarrow 	ext{Mg}^{2+}(g) + 2e^-$$

Question 19

Which of the following best describes the trend in electron affinity across a period (excluding group 8A elements)?

Accepted Answer

Electron affinity becomes more negative (energy released increases) across a period.

Periodic Properties of the Elements: Trends and Explanations

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