Atoms & Molecules Assessment

The diagram shows a model of an atom. Atoms contain three different subatomic particles. Which statement best describes the particle labeled A?

• Particle A exists outside the nucleus.
• Particle A has a negative charge.
• Particle A does not contribute to an atom’s mass.
• All of the above are correct.

Atomic number is the number of ________ in an atom.

• Protons
• Neutrons
• Electrons
• Nuclei

What are the two subatomic particles found inside the nucleus?

• Protons and electrons
• Electrons and neutrons
• Protons and neutrons
• Electrons and ions

Which two subatomic particles have approximately the same mass?

• Protons and electrons
• Electrons and neutrons
• Protons and neutrons
• Electrons and nuclei

Which of the following is a true statement?

• The nucleus is found in the center of atoms and contains protons and electrons.
• The nucleus is found in the center of atoms and contains protons and neutrons.
• Electrons have a neutral charge.
• Neutrons have a negative charge.

What is the role of electrons within an atom?

• Electrons are in the nucleus and have a negative charge.
• Electrons are in the nucleus and have a positive charge.
• Electrons are outside the nucleus and have a negative charge.
• Electrons are outside the nucleus and have a positive charge.

What of the following determines an atom’s identity?

• protons
• neutrons
• electrons
• nucleus

If an oxygen atom has a mass number of 16, how many neutrons are in the atom?

• 5
• 6
• 7
• 8

In a neutral atom, the number of protons and electrons are as follows:

• more protons than electrons
• equal
• more electrons than protons
• need more information

How many neutrons does sodium have?

• 11
• 12
• 23
• 34