1. CHEMISTRY pp

2. Atoms smallest unit is an atom
nucleus: center/core is most of the mass of the atom
a. protons: +
b. neutrons: 0
electron cloud: outermost level needs to be filled with 8 electrons (or 2 for H) and if not it’s reactive

3. Atoms: isotopes Atomic number: number of protons
Atomic weight (mass): number of protons + neutrons
Isotope: different number of neutrons
Changes weight
Ex: C12 vs C14

4. Atoms: ions
Ion: charged atom due to gaining or losing electrons ( Na vs Na+ )

5. Element pure substance that can’t be broken into other types of matter
each element has its own symbol that uses 1 or 2 letters

6. Compounds substance made up of 2 or more elements
compound behaves different than individual elements
EX. Na vs NaCl

7. held together by bonds
a. covalent bonds (strong): 2 or more atoms
share electrons
b. ionic bonds (weak) : attractions between +
and – ions by transferring electrons

8. Chemical Reactions (rxn)
EX. NaOH + HCl  NaCl + H2O
reactants: left side
products: right side
Exergonic/exothermic: release energy like heat, explosion, light etc. – feels warm
endergonic/endothermic: requires energy to occur and takes it from the environment- feel cold

9. Activation Energy energy needed to start a rxn

10. NEED TO MEMORIZE THE FOLLOWING ELEMENTS AND COMPOUNDS FOR YOUR QUIZ AND TEST!
H: hydrogen
O: oxygen
N: nitrogen
C: carbon
Na: sodium
Cl: chlorine
K: potassium
S: sulfur
COMPOUNDS
H2O: water
NaCl: sodium chloride/salt
H2SO4: sulfuric acid
HCl: hydrochloric acid
NaOH: sodium hydroxide
CO2: carbon dioxide
O2: oxygen gas