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20 Cards in this Set
- Front
- Back
|
chemical elements
|
substance that cannot be
split in simpler substance |
|
|
how many elements
|
112 element 92 occur
naturally |
|
|
chemical symbol
|
1 or 2 letters in
english, latin, or another language |
|
|
H, C,O,N,Ca,Na
|
hydrogen, carbon, oxygen,
nitrogen, calcium, sodium |
|
|
elements in body
|
26
|
|
|
96% of elements
|
oxygen, carbon,
hydrogen, nitrogen |
|
|
8 other elements present
in body |
calcium, phosphorus, potassium,
sulfur, sodium, chlorine, magnesium, iron |
|
|
how many additional
elements |
14 trace elements
.2% |
|
|
atoms
|
smallest units
of matter that retain properties of element |
|
|
subatomic particles
|
protons, neutrons,
electrons |
|
|
nucleus
|
dense central
core of atom |
|
|
electron shells
|
electron moving
about central core |
|
|
1st 2nd 3rd + shells
|
2, 8, 18, 18
|
|
|
most massive
element |
iodine
|
|
|
electrons equal
|
protons
|
|
|
atomic #
|
# of protons
|
|
|
mass #
|
sum of protons
and neutrons |
|
|
isotopes
|
different # of
neutrons |
|
|
radioactive isotopes
|
unstable nuclei
decay(change) into stable |
|
|
half-life
|
time required for half
of radioactive atoms to decay into stable form |
