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23 Cards in this Set

  • Front
  • Back
Law of conservation of matter
When a chemical reaction takes place, matter is neither created nor destroyed.
Law of constant composition
Multiple samples of any pure chemical compound always contain the same percent of each element.
John Dalton
Atomic Theory (5)
Discovered electron in 1897.
Thomson and Goldstein
Discovered proton in 1907.
Discovered neutron in 1932.
Plum Pudding
Thomson; Negative electrons in positive pudding. Protons yet to be discovered.
Alpha Particle with Gold Foil in 1909.
Why did only some of the particles reflect at wide angles?
Because sometimes the beam passes through the empty space, which debunks Thomson.
Why did some of the particles reflect at wide angles?
Because there is a small positively charged thing, which Rutherford named nucleus.
Holds an atom's protons and neutrons.
How are electrons held in the atom?
The attraction between + and - charges holds the electrons in the atom.
Atomic Number
Number of protons; alone determines identity of atom.
Mass Number
Protons + number of neutrons.
Different versions of same element; same atomic number, but different number of neutrons. Different masses.
Atomic Mass
Each isotope's atomic mass is multiplied by its percent abundance and results summed.
Law of Mendeleev
Properties of elements recur in regular cycles when arranged in increasing atomic mass.
Atomic Size
Atomic radius increases down a group; increases right to left.
Atom without balanced electron-proton; with net charge.
- Ion.
+ Ion
First ionization energy
Minimum amount of energy required to remove 1 electron from an atom.
Ionization Energy
Decreases down a group; decreases right to left.