Matter
Matter has mass and occupies space
3 states- solid, liquid, gas
about 100 elements found in nature
matter is made of atoms
Elements and compounds;
An element has only one kind of atom
A compound has 2 or more elements in fixed proportions
Atoms and Molecules:
a molecule has 2 or more atoms bonded together
a molecule could be an element orr a compound
substance: 1 element or 1 compound
mixture: 2 or more substances in variable proportions
homogenous: uniform (solution)
heterogenous: non-uniform
adding heat energy can trigger a phase change
protons
postive
in nucleus
neutrons
neutral
in nucleus
electrons
negative
outside the neucleus
atomic number = number of protons
How many electrons?
An atom in neutral
# of electrons = # of protons
An ion is charged
not = to protons
cation: pawwsitive charge
anion: - charge
Mass Number= protons + neutrons
most elemnts have 2 or more ISOTOPES- atoms that have the same atomic number but different mass numbers