emc Flashcards
def elements
simplest structure, cannot be broken down further
def compounds
2 or more elements chemically combined together
how to obtain compounds (4)
- reacting 2 elements
- reacting an element & compound
- reacting a compound & compund
- decomposing a compound
def mixtures
2 or more substances NOT chemically combined together
metals vs non-metals: physical appearance
m: shiny
n-m: dull
metals vs non-metals: melting point
m: high
n-m: low
metals vs non-metals: strength
m: ductile (can be drawn into wires without breaking) & malleable (can be hammered into different shapes
n-m: brittle (fragile)
metals vs non-metals: conductors of electricity & heat
m: good conductor
n-m: poor conductor
metals vs non-metals: state at r.t.p (room temp & pressure)
m: solid
n-m: liquid/gas
mixtures vs compounds: chem/physical changes
m: no chem change & may involve physical change
c: invloves chem change
mixtures vs compounds: transfer of energy
m: little/no energy taken in/ given out
c: energy taken in/given out (usually in the form of light/heat)
mixtures vs compounds: chem/physical properties
m: same chem properties, may be diff physical properties
c: diff chem & physical properties
mixtures vs compounds: separation
m: easily separated by physical methods
c: only separated by chem methods (usually strong heating)
- mixtures vs compounds: proportions *
m: NOT mixed in fixed proportions
c: FIXED proportions (BY MASS)
def physical change
change in physical properties & appearance
same materials, reversible changes
eg!! melting, crushing a box, etc
