Chemistry Chapter 5

quantum mechanical model

- 1926 Austrian Physicist Erwin Schrodinger ( 1887-1961) - used calculations and results to devise and solve mechanical equations describing the behavior of the electron in an hydrogen atom - came from the mathematical solutions of Schrodinger - determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom

Rutherford's atomic model

- could not explain the chemical properties of elements - could not explain why metals or compound metals give off characteristic colors when heated in flame

Photons

- light is this -subatomic particle -travel through space in the same direction -particles of energy -travel at a constant velocity

Light

-created by excited electrons -when atoms release energy it becomes this - it can be fluorescent -consist of waves and particles

plank's constant

6.626 x 10 ^-34

1911

Ernest rutherford finds an atom has a small dense positively charged nucleus

1926

Erwin Schrodinger develops mathematical equations to describe the motion of electrons in atoms which leads to quantum theory

1904

Hantaro Nagoaka suggest that an atom has a central nucleus. Electrons move in orbits like the rings around saturn

1897

J.J. thompson discovers electrons. He pictures electrons embedded in a sphere of positive electrical charge

1932

James Chadwick confirms the existence of neutrons which have no charge. Atomic nuclei contain neutrons and positively charged protons

1803

John Dalton pictures atoms as tiny indestructible particles

1923

Louis de Broglie proposes that moving particles like electrons have some properties of waves

the borh model

Niel's Bohr(1885-1962), young danish physicist a student of Rutherford. - proposed that an electron is found only in specific circular paths, or orbits, around the nucleus

hertz

SI unit of cycles per second

atomic orbital

a mathematical expression describing the probability of finding an electron at various locations around the nucleus. - each energy sublevel corresponds to one or more orbitals of different shapes. - orbitals describe where an electron can be found

spin

a quantum mechanical property of electrons and may be thought of a clockwise or counterclock wise

Pauli exclusion principle

an atomic orbital may describe at most two electrons

wavelength

distance from the peak to the crust to the next peak -it stays the same once a particle of light has one - the greater the mass the less it is - the less the mass, the greater the mass - measured in nonometers

photoelectric effect

electrons are ejected when light shines on metals

Hund's rule

electrons occupy orbitals of the same energy in a way that mae the number of electrons with the same spin direction as large as possible

aufbau principle

electrons occupy the orbitals of lowest energy first

The quantum theory

explains that all particles have a duality of character

1913

in Niels Bohr's model the electron moves in a circular orbit at fixed distances from the nucleus

electromagnetic radiation

includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays

frequency

measure of how many waves pass a location is an amount of time per second

heisenberg uncertainty principle

states that it is impossible to know both the velocity and the position of a particle at the same time

quantum

the amount of energy required to move an electron from one energy level to another

energy levels

the fixed energies an electron can have

amplitude

the wave's height from zero to the crest

electron configurations

the way in which electrons are arranged in various orbitals around the nuclei of atoms

spectrum

when sunlight passes through a prism, the different wavelengths separated into colors

ground state

when the electron is at it lowest possible energy level