Ch 101 test 1

chemistry is the study of

matter

matter is any substance that has

mass

the molecules that are diatomic are

H2 N2 O2 F2 Cl2 Br2 I2

compounds

can be broken down into more elemental particles

atomic theory of matter

the theory that atoms are the fundamental building blocks of matter

each element is composed of extremely small particles

called atoms

atoms are neither created or destroyed in

chemical reactions

Compounds are formed when

atoms of more than one element combine

the atomic nucleus is

tiny

Goldsteins experiment in 1886 observed

positive rays using a perforated cathode

thomson in 1897 determined the

mass-charge ratio of cathode rays: discovering the electron

Radioactivity

the spontaneous emission of radiation by an atom

1911 gold foil experiment discovered the

atomic nucleus

protons and electrons are the

only particles that have a charge

protons and neutrons have essentially the same

mass

the mass of an electron is so small we

ignore it

elements are symbolized by

one or two letters

all atoms of the same element have the same number of

protons

the atomic number corresponds to the number of

protons and neutrons

the mass number of an atom is the sum of the number of

protons and neutrons in the nucleus

isotopes have the same atomic number but different

mass numbers

isotopes have different numbers of

neutrons

average atomic mass is calculated from the

isotopes of an element weighted by their relative abundances

structural formulas show the order in which atoms

are bonded

perspective drawings also show the 3-d array of

atoms in a compound

limiting reactant

the compound that is completely consumed first

black body radiation

light emitted by hot objects

photoelectric effect

Photons with frequencies above a certain threshold can eject electrons from metal surfaces

hydrogen atom emmission spectrum

Hydrogen (and other) gas discharges only emit discrete, characteristic wavelengths of light

a wave is a

disturbance that propagates through space

amplitude is the

maximum disturbance

wavelength is the

distance required for one complete oscillation

frequency is a measure of the number of

waves passing a given point per unit of time

for waves traveling at the same velocity, the longer the waveletngth

the smaller the frequency

constructive wave interference

amplitudes are additive for waves that are in-phase

destructive interference

amplitudes cancel for waves that are out-of-phase

for all waves the product of wavelength and frequnecy is the

waves speed

electromagnetic radiation moves at the

speed of light

𝜈𝜆 = speed and speed is

C (speed of light)

Speed of light

= 2.998 × 10^ 8 m/s

long wavelength

small frequency

short wavelength

high frequency

Wien’s Law

𝜆𝑚𝑎𝑥𝑇 = 2.898 × 10^−3 m ∙ K

The energies of oscillators can only be

integer multiples of a constant times the frequency of oscillation.

energy is absorbed or emitted in

discrete amounts (integer multiples of h𝜈)

An object can gain or lose energy by

absorbing or emitting radiant energy in QUANTA.

energy of radiation is proportional to

frequency

E =

h * v

h =

plancks constant

threshold frequency

t electrons are ejected only when the frequency of the impingent light is greater than a “threshold” frequency.

each photon delivers an energy equal to

E_photon = ℎ𝜈 = ℎ𝑐/ wavelentgh

one photon in

one electron out