Atoms

Atomic Mass

• Average number of different masses

• Mass of an atom = to the number of protons and neutrons

• 1 amu

• The SI atomic unit in a cell

What is the number of protons that the element in this image contain?

• 14
• 7
• 15
• 18

The positive particles of an atom are 

• Electrons 
• Positrons 
• Neutrons 
• Protons 

The central region of an atom where its neutrons and protons are is its _______.

• Nucleus 
• Electron cloud
• Core 
• Center 

An atom with atomic number 6 would have how many protons?

• 6
• 12
• 3
• Cannot be determined 

Particles in an atom that are neutral and have no charge are ______. 

• Negatrons 
• Electrons 
• Neutrons 
• Protons 

What does the nucleus of an atom contain?

• Electrons and neutrons
• Protons and neutrons
• Neutrinos and positrons
• DNA and RN

__________ are negatively charged particles that are in the orbitals around the nucleus.

• protons

• nucleus

• neutrons

• electrons

An electron has a _________ charge

• positive

• neutral

• negative

• massive

Rutherford's gold foil experiment provided evidence that...

• negative and positive charges are spread evenly throughout the atom.
• alpha particles have a positive charge.
• gold is not a dense as previously thought.
• there is a dense positively charged nucleus at the center of an atom.