Atomic - Mass Number & Isotopes

How is the atomic number used to determine the identity of an atom?

• It determines the number of neutrons.

• It determines the number of electrons.

• It determines the number of protons.

• It determines the mass number.

Why are atomic masses not whole numbers?

• Because of the presence of isotopes.

• Because of the number of protons.

• Because of the number of electrons.

• Because of the atomic number.

Given the mass number and atomic number, how are the number of electrons, protons, and neutrons in an atom calculated?

• Electrons = Mass number - Atomic number

• Protons = Mass number - Neutrons

• Neutrons = Mass number - Atomic number

• Protons = Electrons + Neutrons

What does the atomic number of an element represent?

• The number of electrons in an atom

• The number of protons in the nucleus

• The average atomic mass

• The chemical symbol

Which element is represented by the atomic number 1?

• Helium

• Oxygen

• Hydrogen

• Carbon

What is the chemical symbol for Hydrogen?

• He

• H

• Hy

• Hg

What is the atomic number of lead (Pb)?

• 82

• 8

• 30

• 15

If an element has 8 protons, what is its atomic number?

• 8

• 82

• 30

• 15

How many electrons does an element with an atomic number of 30 have?

• 30

• 8

• 82

• 15

What is the atomic number of an element with 82 protons?

• 8

• 30

• 82

• 12