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