atomic structure Flashcards
atomic theory
theory that all matter is composed of atoms
basic unit of matter
atom
pure substance composed of one type of atom
element
pure susbtance composed of atoms of two or more elelments that are chemically combined
compound
compounds always has the same composition by mass (percent)
law of definite proportions
mass is never created or detroyed
law of conservation of mass
mass ratio of elements that are chemically combined can be expressed as whole numbers
law of multiple proportions
whos theory says that matter consists of indivisible particles called atoms and that atoms of a given element are all identical and can neither be created nor destroyed
dalton
what was dalton wrong about
atoms are divisible and they are made of subatomic particles
who discovered atoms consiting of subatomic particles and the electron
jj thompson- by studying the flow of electricty
who discovered electrons
jj thompson
what are atoms charged as
neutral
who did the gold foil experiment and discoverd the atoms nucleus
rutherford
who discoverd the neutron
chadwick
what does atomic nnumber show
(top left)- protons & electrons
where is atomic mass
bottom decimal number
how to find mas number
rounded atomic mass/ p+n
iin carbon-12, what is the mass number
12
how is nuclear notation written
mass number on top, atomic number on bottom, element symbol
how to find number of neutrons
mass number-atomic number
what are isotopes
atoms with the same element, but differnt mass number (differnt top nummber in nuclear notation)
how do u know if an isotope is radioactive
if the atomic number is more than 83
what are cations
positively charged ions that have lost one or more electrons
where does a cations charge come from
how many electrons are being added
what are anions
negatively charged ions which have gained 1 or more electrons
where does a anions charge come from
how many electrons being taken away
what number in the atom changes with isotopes
neutrons
what do letters represent
symbol
how to find mass number from atomic number and neutrons
add them
what do u do when given both isotope info
put percent behind decimal and calculate normal
what if only 1 istope is given
subtract the percent from 100, and then put the answer behind the decimal point
