27 terms

Chemistry ch 3

atoms to moles
divide by Avogadro's #
moles to atoms
multiply by avogadro's number
moles to grams
multiply by the atomic mass
grams to moles
divide by the atomic mass
atoms to grams
divide by avaogadro's # and multiply by the atomic mass
grams to atoms
multiply by Avogadro's # and divide by atomic mass
chemical reaction
transfer of a substance into a new substance
law of conservation of mass
matter is neither created or destroyed during ordinary chemical reactions or physical change.
law of definite proportions
the fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.
law of multiple proportions
If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always the ratio of small whole numbers.
smallest part of an element that retains its physical properties.
John Thompson
discovered electrons through cathode ray tube experiment. plum pudding model of aton
measured the charge of the electron
gold foil experiment to show volume of nucleus was very small compared to the atom itself.
contain most of the mass, positively charged.
atomic number
Number of protons in each atom of that element.
volume is due to
electron cloud
# protons
atomic number
# neutrons
Atomic mass - atomic number
# electrons
equals # of protons
elements of the same element with different masses
Calculate average mass of isotope by
multiplying each mass by the percent and adding them up.
1 amu
1/12 the mass of carbon 12
Average atomic mass
weighted average of the atomic masses of the naturally occuring isotopes of an element.
Avogadro's number
6.022X10^23 number of particles in exactly one mole of a pure substance.
molar mass
mass of one mole of a pure substance in grams/mole
relative atomic mass
The mass of an element relative to calcium 12. The units are atomic mass units wjhich represent 1/12 of the mass of carbon 12.