Atomic Theory Flashcards
Greek Philosopher, building blocks, atoms, no experimental evidence.
Democritus
English chemist and meteorologist, experimental methods, 4 ideas, elements are tiny indivisible particles-atoms, atoms of same element-identical, atoms of diff. element are diff., atome of diff. elements can mix or chemically combine in whole # ratios to form compounds, chemical reactions occur when atoms are separated, combined, or rearranged, atoms of one element are not changed into atoms of another, pool ball analogy.
Dalton
English Chemist, discovered electron w/ Cathode Ray Experiment, plumb pudding model analogy.
Thomson
Electricity passes through a tube, charged plates on either side, ray bent toward the positive plate and away from the negative, concluded rays have negatively charged particles- electrons, must be a positive charge to, to keep the atom stable.
Cathode Ray Tube Experiment
English Physicist, discovered nucleus and proton w/ Gold Foil Experiment, peach analogy.
Rutherford
Positive charged particles shot at gold foil, most went straight through, some were deflected, atom has a small dense core-nucleus.
Gold Foil Experiment
Danish Physicist, built on Rutherford, Planetary Model- electron in orbitals or energy level, is fixed, like a ladder, electrons can jump between levels, can’t be between levels, like a person on a ladder, solar system analogy.
Bohr
Number of Protons in element
Atomic Number
Number of Protons & Neutrons in the nucleus
Mass # (x on periodic table)
A group of atoms with a positive or negative charge, when atoms gain or lose electrons.
Ions
Positive, lost electrons
Cation
Negative, gained electrons
Anion
Atoms with the same number of protons, but a different number of neutrons
Isotopes
Weighted Average of masses of all an element’s isotopes (On Periodic Table)
Average Atomic Mass
