Mass Number

True or false: The mass number is the number of protons + the number of neutrons.

• True

• False

If an element has 5 protons and 9 neutrons, what is its mass number?

• 14

• 5

• 9

• 2

If an element has 1 proton and 0 neutrons, what is its mass number?

• 0

• 1

• 2

• 3

A phosphorus atom has 15 protons. It has a mass number of 31. How many neutrons does it have?

• 15

• 16

• 31

• 6

Which of the following best describes the mass number of an atom?

• The number of protons in the nucleus

• The number of neutrons in the nucleus

• The total number of protons and neutrons in the nucleus

• The number of electrons in the atom

What is the mass number of an oxygen atom with 8 protons and 8 neutrons?

• 8

• 16

• 24

• 32

Use the model shown below to answer the following question. What is the mass number of the atom? (8.5A)

• 6

• 11

• 16

• 10

Tags

NGSS.MS-PS1-1

What is the mass # of atom B?

Mathematical Equivalence

OFF

Tags

NGSS.MS-PS1-1

Explain why isotopes of the same element have different mass numbers but the same atomic number.

• Isotopes have different numbers of protons.

• Isotopes have different numbers of electrons.

• Isotopes have different numbers of neutrons.

• Isotopes have different numbers of atoms.

Tags

DOK Level 3: Strategic Thinking

What is the mass # of atom A?

Mathematical Equivalence

OFF

Tags

NGSS.MS-PS1-1