Chapter 11: Modern Atomic Theory

Ernest Rutherford

1. nucleus is composed of protons & neutrons

2. nucleus is very small compared to entire size of atom

3. electrons revolve around the nucleus like the planets revolve around the sun

examples of electron radiation

holding your hand few inches from the light bulb; move close to wood in a fireplace; energy you feel from the sun

electromagnetic radiation

energy is transferred from one place to another by light

properties of wavelengths

1. wavelength

2. frequency

3. speed

wavelength

distance between two consecutive wave peeks

frequency

indicates how many wave peaks pass a certain point per given time period

speed

indicates how fast a given peak travels through water

photon

a stream of tiny packets of energy

process of emission of energy by atoms

1. atoms receive energy from some source

2. become excited

3. release energy by emitting light

4. emitted energy is carried away by a photon

high energy photons

short wavelength

low energy photons

long wavelengths of light

excited state

atom with excess energy; can release some or all of its excess energy by emitting a photon->move lower energy state

ground state

lowest possible energy state of an atom

quantized

only certain values are allowed

Bohr theory

atom could be pictured as a small positive nucleus w/ electrons orbiting around it

Bohr's model

hydrogen atom with quantized energy levels that agreed with hydrogen emission

Bohr's suggestion

electron could jump to a different orbit by emitting a photon of light with exactly correct energy content

Bohr's atom

energy levels in hydrogen atom represented certain allowed circular orbitals

Louis Victorde Broglie & Erwin Schrodinger

light seems to have both wave & particle characteristics (it behaves simultaneously as a wave & as a stream of particles), electron might also exhibit both of these characteristics

Schrodinger

carried out mathematical analysis of Bohr's idea; led to a new model for hydrogen atom that seemed to apply equally well to other atoms

orbital

probability map for hydrogen electron

1s

hydrogen electron's lowest energy state

orbital level

number tells principle energy level; letter tells shape;

s

spherical orbital

p

two-lobed orbital

x,y,z, subscript on p orbital label

coordinate axes two lobes lie

electron spin

two electrons must have opposite spins to occupy same orbital

orbital diagram

orbitals are represented by boxes grouped by sublevel with small rows indicating electrons

metal properties

lustrous appearance; ability to change shape w/o breaking; can be pulled into a wire or pounded into a thin sheet; excellent conductivity of heat & electricity

nonmetal properties

do not have physical properties

exceptions of atomic properties

solid iodine is lustrous; graphite form of carbon is an excellent conductor of electricity; diamond form of carbon is an excellent conductor of heat

metalloids

elements that exhibit both metallic and nonmetallic behavior

ionization energy

energy required to remove an electron from an individual atom in gas phase

nonmetals

large ionic energy

atomic size

across a period requires a little thought about the atoms in a given row (period) of periodic table

wave mechanical model

electron has both wave and particle characteristics

Pauli exclusion principle

atomic orbital can hold a maximum of two electrons, and those electrons must have opposite spins

levels

...

sublevels

...

electron configuration

...

core electrons

...

lathanide series

...

actinide series

...

main-group elements

...

metals

...

principle energy levels

series of energy levels

atomic size decreases

left to right

atomic size increases

up to down