chem112Chapter2 Flashcards
the Atomic Theory of Matter
some Greek philosophers thought that there was a smallest particle “atomos” (uncuttable) that made up all of nature
“atomos”
means uncuttable
Law of Constant Composition
compounds have a definite composition, same number of atoms for the same compounds
Joseph Proust
discovered the law of constant composition
Law of Conservation of Mass
the total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place
Antoine Lavoiser
discovered the law of conservation of mass
Law of Multiple Proportions
If two elements form more than one compound, the masses of one that combine with a given mass of another are in the ration of small whole numbers, when two or more compounds exist from the same elements, they can not have the same relative number of atoms
John Dalton
developed postulates that became scientific law
Cathode Rays
streams of negatively charged particles found to emanate from cathode tubes that glow
J. J. Thomson
discovered cathode rays
Millikan Oil-Drop experiment
determined the charge/mass ratio of the electron
Robert Millikan
determined the charge on the electron in 1909
Radioactivity
the spontaneous emission of high-energy radiation by an atom
Henri Becquerel
first discovered radioactivity
Marie and Pierre Curie
also studied radioactivity
Three kinds of particles
a particles
b particles
y rays
a particles
positively charged +2
b particles
negatively charged -1
y rays
uncharged
plum pudding model
electrons in a positively charged sphere like a raisin cake
Ernest rutherford
discovered the nucleus in his gold particle experiment
atom size
1-5 Å
Isotopes
atoms of the same element with different masses
atomic mass unit (amu)
1 amu = 1.66054 x 10^-24
spectrometer
measures the atomic mass of a molecule or atom
atomic weight
= Ʃ [(isotope mass) × (fractional natural abundance)]
rows
periods
columns
groups
empirical formulas
give the lowest whole-number ratio of atoms of each element in a compound
Molecular formulas
give the exact number of atoms of each element in a compound
STructural formulas
show the order in which atoms are attached, not the three dimensional shape
perspective drawings
show a drawing of a three-dimensional molecule
ball and stick models
show a three-dimensional picture of a compound with sticks to show the angles of each bond
space-filling models
show a compound if it was to scale
ion
formed when an atom of a group of atoms loses or gains electrons
cations
formed when at least one electron is lost
anions
formed when at least on electron is gained
polyatomic ions
formed when groups of atoms gain or lose electrons
Ionic compounds
formed between metals and nonmetals
chemical nomenclature
naming compounds
organic chemistry
the study of carbon
hydrocarbons
compounds containing only carbon and hydrogen
alkanes
the simplest compounds containing only carbon and hydrogen
isomers
two molecules or more molecules that have the same chemical formula
can a scientist believe in God?
yes
