Unit 1 Flashcards
isotopes
atoms of the same element with different masses
example of an isotope
U-235
average atomic weight
average weight of a naturally occurring mixture of an elements isotopes
When determining average atomic weight we consider the ____ of the isotopes as found in nature
percent
where do electrons exist
only in certain areas outside the nucleus called energy levels
how many energy levels are on the periodic table
7
what do protons determine ?
the identity of the element
what is the atomic number
number of protons
what is the atomic mass
mess of the nucleus (protons plus neutrons)
Comes from the Average of the abundance in isotopes
how to find neutrons
mass #- atomic #
on the left which numbers go on top/bottom?
top is the mass
bottom is the atomic #
ions
atoms with a charge
do protons equal electrons in ions ?
noo
if its a negative charged ion you,,,
add electrons
if its a positive charged ion you…
remove electrons
intrinsic properties
dont change regardless of sample size *many on periodic table
extrinsic properties
do change depending on sample size
ex of intrinsic
color, density, boiling point
ex of extrinsic
volume, length, mass, width
The higher the abundance (quantity) and percent composition, the close the ________ is to that number
Average mass
Discovered electron, charge and mass
Jj Thomson
Discovered nucleus/proton, charge, mass
Ernest Rutherford
Bohr model of an atom
Electrons move within certain energy levels/orbit around nucleus
Niels Bohr
Neutron, charge, mass
James Chadwick
