Atomic Theory & Structure

Isotopes are elements with a different amount of

• protons
• neutrons
• electrons
• atoms

J.J. Thomson provided evidence that an atom...

• is the smallest particle of matter
• contains negatively charged particles
• has an overall negative charge
• has an overall positive charge

Rutherford discovered the...

• electron
• proton
• neutron
• nucleus

Which particle does not contribute mass to the atom?

• Proton
• Neutron
• Electron
• Nucleus

an element will always have the same number of 

• neutrons
• protons
• isotopes
• atoms

An ______________ is the same element, with the same number of protons, but different numbers of neutrons

• Atom
• Isotope
• Atomic Number
• Mass Number

The smallest particle into which an element can be divided and still be the same substance

• neutron
• atom
• electron

How many protons are in this element?

• 79
• 196
• 117
• Cannot be determined

What is the atomic mass (rounded to the nearest whole number) of this element

• 196
• 196.95
• 197
• 79

Because atoms are neutral, the number of protons will be equal to the number of __________ in an atom.

• Positrons
• Neutrons
• Electrons
• Nuclei