History of the Atom

Democritus
atoms cannot be further divided
John Dalton
The Atomic Theory
1) elements are made of atoms
2) all atoms of certain element are identical
3) atoms of different elements have different properties
4)atoms of one element cannot change into another element-atoms are not created or destroyed.
5)compounds are more than 1 element combined
6)the kind of atoms are constant in a compound
parts of atomic theory
J.J. Thompson
discovered the electron with cathode tube experimen, “Plum Pudding”/ “Raisin Model”
Robert Milikan
oil drop experiment. determined mass of an electron and magnitude of its charge
Ernest Rutherford
3 types of radiation. Gold foil experiment
what are the 3 types of radiation
beta –
gamma neutral
alpha +
what did Milikan conclude from his oil drop experiment?
-the nucleus is positive
-has protons….which are +
-dense nucleus with electrons/space surrounding it
Niels Bohr
– presented model of hydrogen
– solar-sytem- like model: orbits
– each orbit has specific energy level
**not entirely accurate because it only explained on level of 1 electron
Erwin Schrodinger
-Wave mechanical model
-thought of electron location in “probabilities”
-orbitals (regions of space) -NOT orbits
Heisenberg
-uncertainty principle: said it was
Not possible to measure precisely the location/velocity of electrons
James Chadwick
-Neutrons!
-said since you couldn’t account for
All the mass in an atom with just
The protons and electrons…there
Must be more particles
– neutrons have mass same size of that of the proton
electromagnetic radiation
A FORM OF ENERGY THAT EXHIBITS WAVELIKE BEHAVIOR AS IT TRAVEL THROUGH SPACE
wavelength
distance from one wave to the base of the next
frequency
number of waves that pass a certain point in a particular amount of time, usually a second
electromagnetic spectrum
CONSISTS OF ALL
ELECTROMAGNETIC RADIATION, ARRANGED ACCORDING TO INCREASING WAVELENGTH
y rays (Gamma) – x rays- ultraviolet- visible- infared- microwaves- radio waves
electromagnetic spectrum- name by increasing in wavelength
inverse
________ relationship between frequency and wavelength
infrared, visible light, ultraviolet, x rays, gamma rays
kinds of electromagnetic radiation (5)
1. WHEN AN OBJECT MADE OF A MATERIAL THAT DOES NOT BURN IS HEATED, IT GIVES OFF LIGHT.

2. PHOTOELECTRIC EFFECT

what are 2 properties of wave that could not be explained by wave theory?
emission of electrons from certain metals when light shines on them
what is the photoelectric effect?
photon
an individual quantum of light
ground level
THE STATE OF LOWEST ENERGY OF AN ATOM
excited state
A STATE IN WHICH IT HAS A HIGHER POTENTIAL ENERGY
THAN IT HAS IN ITS GROUND STATE
Mosely
organized the elements according to atomic number

Pauli

exclusion principle (electron configuration)

-no 2 electrons can have same 4 quantum numbers

Mendeleev
first to organize elements according to atomic mass
Hund

"everyone gets own room"

-get own orientation before have to share

-takes more energy to share rooms

 

Aufbau

principle

-fill lowest energy level possible first

Avogadro
his number…mole day
Proust
Law of definite proportions, compund always contains same elements

Lavoisser

Conservation of Mass
Bacon
observation and experimentation
x

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