chemistry 122

exam 1. Chapter R, 1, and 2.

kilo-

milli-

micro-

nano-

10³

10^-3

10^-6

10^-9

scientific method

collecting data, formulating a hypothesis, testing hypothesis

law of definite proportion (constant proportion)

a given compound always contains exactly the same proportion of elements by mass

law of multiple proportions

when 2 elements form a series of compounds the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers

daltons atomic theory

Elements are made of atoms;

All atoms of an element are identical, but the atoms of one element are different from the atoms of all other elements.

atoms are neither created nor destroyed,

compounds are formed with atoms of more than one element combining and a given compound always has the same relative number and kind of atom

JJ Thomson (1888-1903)

cathode ray tube → charge to mass ration of an electron, plum pudding model

Rutherford (1911)

particles →thin metal foil

determined there was a nucleus so nuclear atom

Niels Bohr (1912-1913)

showed that electrons exist in defined orbits

wavelength

distance between crests. long wavelenths have low frequencies and lower energy

amplitude

intensity or brightness

electromagnetic spectrum from high to low frequency (v)

gamma rays, x-rays, UV, IR (infrared waves), microwaves, radio waves, long radio waves

interaction between waves

constructive __

destructive __

interference

waves that interact so they ADD to make a larger wave

waves that interact so they CANCEL each other out of phase

Planck quantum theory

atoms emit E in packets

radiant energy is emitted or absorbed only in discrete quantities

smallest packet is a quantum

constant: 6.626 × 10^-34 Js