Chapter 2 Flashcards
law of constant composition
compounds have definite composition; # of atoms in compound = always the same
law of conservation of mass
total mass of substances present at end of chemical process=same as mass of substances before
law of multiple proportions
if 2 elements combine to form a compound, the masses combined = ratio
dalton’s atomic theory (5 parts)
- matter = made of atoms
- atoms of 1 element = identical
- atoms of diff element= diff weights/properties
- atoms of diff elements combine to form compounds
- atoms aren’t created or destroyed
cathode rayes
(-) particle stream travels through (+) electrode; study electrons
Millikan oil-drop experiment
determined charge of electron = (-)
radioactivity
spontaneous emission of high-energy radiation
3 types of radiation
alpha, beta, gamma
alpha radiation
(+) charge; decay emission = 2 p + 2 n
beta radiation
(-) charge; decay emission = 1 e
gamma radiation
no charge; decay emission = gamma ray
“plum pudding model”
even spread of + charges through atom; radiation passes through center, rejected
nuclear atom (Rutherford, gold foil experiment)
most mass and (+) - dense nucleus; (-) moves in space around
subatomic particles
protons, neutrons, electrons; opposite charged attract, same repel
protons
1+
neutrons
neutral
electrons
1-
1 amu
1.66054 x 10^-24 g
atomic number
number of protons (=number of electrons)
mass number
protons + # neutrons
isotopes
atoms of same element
- (same atomic number- # proton = # electrons)
different masses (# of neutrons)
atomic weight
average atomic mass of element (using isotopes)
(isotope mass)x(fractional abundance)= atomic weight
mass spectrometer
determines atomic weights w/ accelerator
of protons =
of electrons
