Atoms and Subatomic Particles Quiz

Atoms Consist of Subatomic Particles

• Atoms are the smallest unit of matter that retains an element's properties.
• Atoms consist of protons, neutrons, and electrons.

Subatomic Particles

• Protons have a positive charge (+).
• Electrons have a negative charge (-).
• Neutrons have no charge.

Atomic Number

• The atomic number of an element is the number of protons in its atoms.
• Elements have unique numbers of protons.
• Every atom of a specific element has the same number of protons.

Mass Number

• The mass number of an atom is the total number of protons and neutrons in its nucleus.
• Protons and neutrons have nearly the same mass.
• Electrons have a much smaller mass.

Isotopes

• Isotopes of an element have the same number of protons but different numbers of neutrons.
• Isotopes have the same atomic number, but different mass numbers.

Atomic Mass

• Atomic mass is approximately equal to the mass number.
• Atomic mass is expressed in daltons.

Models of Atoms

• Models of atoms show electrons orbiting the nucleus.
• Current models show electrons as a cloud around the nucleus.
• Models are not drawn to scale. Nuclei are much smaller than electron clouds.

Radioactive Isotopes

• Radioactive isotopes have unstable nuclei.
• Radioactive decay releases particles and energy.
• Radioactive decay can damage cells but also has uses in dating and research.