3.1 - The mass of atoms

Question 1

What is the relative mass of protons and neutrons?

Answer 1

1

Question 2

What is the mass number of an atom?

Answer 2

The total number of the protons and neutrons in its nucleus

Question 3

What is the atomic number of an atom?

Answer 3

Its number of protons (which equals its number of electrons)

Question 4

What do atoms of the same element all have?

Answer 4

The same atomic number (the same number of protons and electrons)

Question 5

What can atoms of the same element have different numbers of?

Answer 5

Neutrons

Question 6

What are isotopes?

Answer 6

Atoms of the same element with different numbers of neutrons

Question 7

How can we calculate the number of protons, electrons, and neutrons in an element using the periodic table?

Answer 7

• The number of protons is the atomic number
• The number of electrons is the same as the number of protons (atomic number)
• The number of neutrons is the number of protons (atomic number) subtracted from the total number of protons and neutrons (mass number)