Cathode Ray Tubes
J.J. Thomson/Robert A. Milikan, discovery that electrons are negative in charge. Tube filled with low pressure gas with circuits at two ends, electrons enter tube, when tube is powered a light is shown showing electron path, with two magnets at opposite ends of tube light goes to positive (electrons=negative charge).
Rutherford's Gold Foil Experiment
Alpha particles are thrown through gold foil, supposed to pass through but 1 in every 8000 particles are deflected. Shows that atoms contain high density center (nucleus) which caused alpha particles to bounce back.
Law of Conservation of Mass
Mass can be neither created nor destroyed, it can only change form.
Law of Definite Proportions
The chemical composition of a compound stays the same regardless of the size/source (water is always h2o whether comes from ocean or river, or 2 mL or 1000 mL)
Dalton's Atomic Theory
1. elements are made of extremely small particles called atoms (true) 2. All atoms of a given element are identical (true) 3. Atoms cannot be subdivided, created, or destroyed (false) 4. Atoms combine in ratios to form chemical compounds...H2O (true) 5. Chemical reactions result in atoms combining, separating, and rearranging (true)
Everything is made of atoms
Modern Atomic Theory
1. All matter is composed of atoms 2. Atoms of any one element differ in properties from atoms to another element
Atomic Number (Z)
The number of protons in atom (identical to number of electrons) (bottom number in complete nuclear symbol)
Number of protons plus the number of neutrons (top number in complete nuclear symbol)
Holds nucleus of atom together
When the # of protons does not match the # of electrons in an atom, gives atom net charge
Atoms of same element with different masses due to different # of neutrons than protons
Conversion factor allowing one to convert mole to particles and vice versa (1mol=6.022x10²³atoms)
The mass of 1mol of a pure substance (1mol=#grams of element)