Question 1

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

Accepted Answer

The effective nuclear charge increases, pulling electrons closer to the nucleus.

Question 2

Which element would you expect to have the highest first ionization energy?

Accepted Answer

Fluorine (F)

Question 3

Why is the ionic radius of $\mathrm{Cl^-}$ larger than the atomic radius of $\mathrm{Cl}$?

Accepted Answer

The chloride ion has gained an electron, increasing electron-electron repulsion.

Question 4

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity decreases down a group and increases across a period.

Question 5

A neutral magnesium atom ($\mathrm{Mg}$) has a radius of 145 pm. Its most common ion ($\mathrm{Mg^{2+}}$) has a radius of 73 pm. What is the best explanation for this difference?

Accepted Answer

The ion has lost two electrons, reducing electron-electron repulsion and allowing the nucleus to pull the remaining electrons closer.

Question 6

Which of the following elements is most likely to form a cation with a $+1$ charge?

Accepted Answer

Sodium (Na)

Question 7

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

Accepted Answer

Ionization energy decreases because the outer electrons are farther from the nucleus and more shielded.

Question 8

Which of the following pairs of elements would you expect to have the most similar chemical properties?

Accepted Answer

Sodium (Na) and Potassium (K)

Question 9

Which of the following best explains why fluorine is the most electronegative element?

Accepted Answer

Fluorine has a small atomic radius and a high effective nuclear charge, so it attracts electrons strongly.

Question 10

Which of the following elements would be expected to have the lowest melting point?

Accepted Answer

Sodium (Na)

Question 11

A student claims that the first ionization energy of potassium (K) is higher than that of sodium (Na). Is this correct? Why or why not?

Accepted Answer

No, because potassium's outer electron is farther from the nucleus and more shielded, making it easier to remove.

Question 12

Which of the following best describes the trend in metallic character as you move from left to right across a period?

Accepted Answer

Metallic character decreases.

Question 13

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

Accepted Answer

$\mathrm{Na^+}$

Question 14

Which of the following best explains why metals are more reactive as you move down a group?

Accepted Answer

The ionization energy decreases, making it easier to lose electrons.

Question 15

Which of the following statements about the shielding effect is correct?

Accepted Answer

The shielding effect remains relatively constant across a period.

Question 16

Which of the following elements would you expect to have the highest density?

Accepted Answer

Iron (Fe)

Question 17

Which of the following best explains why the second ionization energy of sodium is much higher than its first ionization energy?

Accepted Answer

The second electron is removed from a stable noble gas configuration.

Question 18

Which of the following best describes the trend in atomic radius as you move down a group?

Accepted Answer

Atomic radius increases due to the addition of energy levels.

Question 19

Which of the following elements is most likely to form a covalent bond with hydrogen?

Accepted Answer

Chlorine (Cl)

Question 20

Which of the following best explains why nonmetals are more reactive as you move up a group?

Accepted Answer

The electronegativity increases, making it easier to attract electrons.

Periodic Trends and Element Properties: Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards