Chem
Exam next monday

-structure of an atom
*proton (+)
*neutron
*electrons (-)

12
6  C

Upper # is number of protons
Bottom # is the number of protons/electrons
letter is the symbol

isotopes
different numb of neutrons

atomic mass
 mass spectrometer

average mass
average of all the isotopes in nature

group 1 alkaline
alkaline earth
halogens
noble gases 

non metals-metaloids

molecular compounds are composed of molecules and almost always contain only nonmetals



natural occuring 2 atoms
hydrogen
nitrogen
oxygen
fluorine
chlorine
bromine
iodine

types of formulas
-empirical formulas give the lowest whole number ratio of atoms of each element in a compound
-molecular formulas give the exact number of atoms of each element and compounds

ions
when atoms lose or gain electrons, they become ions
-cations are positive and are formed by elements on the left side of the periodic chart
-anions are negative and are formed by elements on the right side of the periodic chart 

fluorine--->fluoride for anion
bromine--->bromide for anion

accatate nitrate  perchlorate

sulfate 

oxyanion
-when there are two oxyanion