Question 1

Which of the following statements best explains why Mendeleev's periodic table was able to predict the properties of undiscovered elements such as gallium and germanium?

Accepted Answer

He arranged elements by increasing atomic mass, which caused elements with similar properties to fall into columns.

Question 2

Which of the following electron configurations represents a noble gas?

Accepted Answer

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

Question 3

How many valence electrons does magnesium (Mg) have, and what is its condensed electron configuration?

Accepted Answer

2 valence electrons; $$[Ne] 3s^2$

Question 4

Which of the following elements has the largest atomic radius?

Accepted Answer

Rb

Question 5

What is the trend in atomic radius as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic radius decreases due to increasing effective nuclear charge.

Question 6

Which of the following ions is isoelectronic with Ne?

Accepted Answer

All of the above

Question 7

Arrange the following ions in order of increasing ionic radius: $$Na^+$$, $$Mg^{2+}$$, $$Al^{3+} ($$all are isoelectronic).

Accepted Answer

$$Al^{3+}$$ \u003c $$Mg^{2+}$$ \u003c Na^+$$

Question 8

Which of the following statements about ionization energy is correct?

Accepted Answer

Ionization energy increases from left to right across a period due to increasing effective nuclear charge.

Question 9

Which element in group 15 (the nitrogen group) has the smallest first ionization energy?

Accepted Answer

Bismuth (Bi)

Question 10

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 11

Which group of elements is most likely to form $$+1$$ ions?

Accepted Answer

Group 1 (alkali metals)

Question 12

Which of the following statements about metallic character is true?

Accepted Answer

Metallic character decreases from left to right across a period.

Question 13

Which of the following elements has the highest first ionization energy?

Accepted Answer

Fluorine (F)

Question 14

Which of the following best explains why cations are smaller than their parent atoms?

Accepted Answer

Cations have fewer electrons, resulting in less electron-electron repulsion and a higher effective nuclear charge.

Question 15

Which of the following groups has negative electron affinities?

Accepted Answer

Group 17 (halogens)

Question 16

Which of the following is the correct order of atomic radius from smallest to largest for the elements Mg, Na, P, Si, and Ar?

Accepted Answer

Ar \u003c P \u003c Si \u003c Mg \u003c Na

Question 17

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

Accepted Answer

$$Z_{eff} is $$the net positive charge experienced by valence electrons after accounting for shielding by core electrons.

Question 18

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

Accepted Answer

First ionization energy decreases due to increased atomic radius and shielding.

Question 19

Which of the following elements is most likely to have a filled $$s$$ and $$p$$ subshell in its outermost energy level?

Accepted Answer

Neon (Ne)

Question 20

A patient is exposed to a large amount of sodium ions ($$Na^+) in a $$medical treatment. Which of the following best describes the electron configuration of $$Na^+$$?

Accepted Answer

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

Periodic Properties of the Elements (General Chemistry Study Notes)

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