1. The Chemical Basis of Life

2. Matter: anything that has mass and takes up space
Atom: basic unit of matter
Atomic # = # of protons (and electrons)
Atomic mass = atomic # + # of neutrons
Isotopes: atoms of the same element with different #’s of neutrons (different atomic weights)

3. # + atomic # = atomic weight
Subatomic particles
Particle
Location
Charge
Mass
Other
Proton
Nucleus + 1
Equal to atomic #
Neutron
# + atomic # = atomic weight
Electron
Outside nucleus -
Usually = # of protons

4. Atoms are most stable when they have full outer “shells”
1st shell is full with 2, the rest with 8
When atoms share electrons to stabilize they form a covalent bond
When atoms give up or gain electrons they become charged particles or ions
Oppositely charged ions are attracted to one another in an ionic bond

5. Molecule: two or more atoms bonded together
Compound: when atoms of different elements are combined