$\text{Atomic mass} = \text{Number of protons} + \text{Number of neutrons}$

Question 1

Which of the following statements best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 2

A neutral atom of sodium (Na) has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

Accepted Answer

$23 - 11 = 12$ neutrons

Question 3

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

Accepted Answer

They have a full outer shell of electrons.

Question 4

What is the charge of an ion formed when a chlorine atom gains one electron?

Accepted Answer

$-1$

Question 5

Which of the following is the correct formula to calculate the atomic mass of an atom?

Accepted Answer

$	ext{Atomic mass} = 	ext{Number of protons} + 	ext{Number of neutrons}$

Question 6

Which statement about electrons is correct?

Accepted Answer

Electrons are found in orbitals surrounding the nucleus.

Question 7

How many electrons can the second energy level (Period 2) of an atom hold?

Accepted Answer

8

Question 8

A carbon atom has 6 protons and 7 neutrons. What is its atomic mass?

Accepted Answer

$6 + 7 = 13$ atomic mass units (amu)

Question 9

Which of the following best describes the role of valence electrons?

Accepted Answer

They determine the chemical reactivity and bonding of an atom.

Question 10

Which of the following elements is most likely to form a +2 ion?

Accepted Answer

Magnesium (Mg)

Question 11

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic number?

Accepted Answer

17

Question 12

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of electrons and protons.

Question 13

Which of the following is true about ions?

Accepted Answer

Cations are positively charged ions formed by losing electrons.

Question 14

A neutral atom of oxygen has 8 protons and 8 electrons. If it gains 2 electrons, what is the resulting charge?

Accepted Answer

$-2$

Question 15

Which of the following best describes the trend in atomic number across a period in the periodic table?

Accepted Answer

It increases from left to right.

Question 16

Which orbital can hold a maximum of six electrons?

Accepted Answer

p orbital

Question 17

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 18

A fluorine atom has 9 protons and 10 neutrons. What is its atomic mass?

Accepted Answer

$9 + 10 = 19$ atomic mass units (amu)

Question 19

Which of the following best describes the relationship between atomic number and the number of protons in an atom?

Accepted Answer

The atomic number is equal to the number of protons.

Question 20

Which of the following elements is most likely to form a -2 ion?

Accepted Answer

Oxygen (O)

Atomic Structure: Fundamentals and Applications

Study Guide - Practice Questions