8th Chapter 9 Understanding Atoms Review

The atomic theories of _______________ included the idea that atoms cannot be divided, created, or destroyed.

• Democritus and Aristotle

• Dalton and Democritus

• Dalton and Bohr

• Dalton and Thomson

Two atoms of different elements will definitely have different numbers of

• nuclei

• protons

• neutrons

• electrons

Two neutral atoms that have the same atomic number and different mass numbers are...

• ions.

• isotopes.

• alpha particles.

• different elements.

An ion that has a negative charge is formed when an atom...

• loses neutrons.

• loses electrons.

• gains neutrons.

• gains electrons.

The ____________________ is a weighted average that reflects the abundance of different isotopes.

• nucleus

• average atomic mass

• atomic mass

• mass number

What happens to the atomic number of an element when it emits an alpha particle?

• The atomic number decrease by 1.

• The atomic number decreases by 2.

• The atomic number stays the same.

• The atomic number is divided in half.

The atomic number increases by 1 when _________is released?

• a beta particle

• a gamma particle

• an alpha particle

• an electron

What does a gamma ray consist of?

• energy

• 1 proton

• 2 neutrons

• 4 electrons

What change in the atomic number of an element could be recorded if a gamma ray is released?

• No change.

• The atomic number increases by 2.

• The atomic number decreases by 1.

• The atomic number increases by half.

Which particle has a positive charge?

• electron

• orbital

• proton

• neutron