• Each element gives off a specific color of light ( emission spectra)
  -unique to each element
• If electrons absorb energy they can be bumped to a higher level
• When they fall to a lower level they release energy as light

Atomic Structure

• Atoms are made up of parts called subatomic particles
  -Protons
  -Neutrons
  -Electrons
• Atomic number equals the number of protons

Isotopes

• # of protons determine the type of element
• changing the number of neutrons changes the isotope of the element
• all isotopes have the same chemical properties

Mass Number

• mass# is the total of protons and neutrons
• Different isotopes have different mass
• ex. How many protons and neutrons are in Na?
  -Na has 11 protons with mass number of 23
  -therefore Na has 12 neutrons and 11 protons