-112 different types (elements)

-make up everything

-ageless

Who came up the idea of the atom?

-Democritus

-distinct types of atoms

-Everything is made up of a combination of elements

-112 types... 88 found naturally 

-90% of atoms are hydrogen

-Hydrogen= the original element

-heavy atoms made inside stars

-light atoms are the remains of exploded stars

1.Hydrogen

2.Carbon

3.Oxygen

4.Nitrogen

-electrons, protons, and neutrons

-nucleus= center of atom (containing protons and neutrons)-most mass contained here

-Robert Brown

-Noticed constant agitation of grains of pollen

-Browninan Motion-jiggling of particles--result of collisions between particles and invisible atoms

-surrounds nucleus

-dictate chemical behavior

-negatively charged

-glowing ray produced inside sealed gas filled tube when voltage is applied across electrodes

-when electric charge brought near tube--ray deflected towards negative charge and away from positive charge

-indicated ray was negatively charged 

-measured deflection of angles of cathode-ray particles in a magnetic field

-deflection depends on:mass of particles and electric charge 

-plum pudding atom model (electrons "plums" in a sea of positively charged "pudding")

-figured out how to calculate the mass of a cathode-ray particle

-discovery that there is something smaller than an atom-- electron

-new model of atom: mostly empty space with a small, dense, nucleus

-experiment:alpha particles through gold foil...most passed straight through.. a few deflected (hit nucleus)

-much more massive than electron, but contains equal charge

-positively charged

-# of protons is balanced by # of electrons

-# of protons an atom contains

-elements classified by this

-found in nucleus

-no charge

-same mass as proton

total mass of an atom

neutrons+electrons+protons

-planetary model of the atom

-electrons orbit around like planets

-layers get closer and closer together (out from nucleus)

-vibrating corpuscle of light

-higher frequency=more energetic

-violet and blue have more energy than red and green

-energy is directly proportional to frequency

-photon of light is emitted when electron jumps from higher energy to lower energy

-atom at high energy level

-de-excites when photon is emitted

-showed certain regions of space centered about the nucleus where an electron of a given energy state was most likely found

-developed by Heisenburg and Schrodinger through calculations

-improvement of planetary model