Atomic Structure: Mass Number & Isotopes

Question 1

Atomic Number

Answer 1

• The number of protons in an atom

- Known as (Z)

Question 2

Mass Number

Answer 2

• The mass number of an atom is the number of protons plus the number of neutrons
• Known as (A)

Question 3

What are isotopes?

Answer 3

• Isotopes are atoms of the same element that contain different numbers of neutrons

Question 4

Compare and explain the reactivity of two isotopes of the same element

Answer 4

• The chemical reactivity of different isotopes of an element is identical because they have the same electronic structure

• The different masses of the atoms means that physical properties of isotopes are slightly different

Question 5

Relative Atomic Mass

Answer 5

• The relative atomic mass of an atom is the average mass of one atom of an element relative to 1/12 the mass of one carbon-12 atom