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Chapter 2 Notes

things that might be important from chapter 2
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Democritus and early Greek philosophers
thought the material would must be made of tiny invisible particles called atomos meaning "indivisible or uncuttable"
Isaac Newton
favored the idea of atoms
John Dalton
created Dalton's atomic theory
Dalton's atomic theory-1
Each element is composed to extremely small particles called atoms
Dalton's atomic theory-2
All atoms of a given element are identical to one another in mass and other properties, but the atoms of one element are different from the atoms of all other elements.
Dalton's atomic theory-3
The atoms of one element cannot be changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions
Dalton's atomic theory-4
Compounds are formed when atoms of more than one element combine; a given compound always has the same relative number and kind of atoms
atoms
smallest particles of an element that retain the chemical identity of the element
law of conservation of mass
The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.
law of multiple proportions
if two elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers.
subatomic particles
the atom is composed of these smaller parts
particles with the same charge
repel one another
particles with unlike charges
attract one another
cathode rays
radiation produced from the negative electrode when high voltage was applied to partially excavated tubes
cathode
negative electrode
J. J. Thomson
observed cathode rays and discovered the electron, "plum-pudding model"
Robert Millikan
oil-drop experiment; discovered the mass of an electron
radioactivity
the spontaneous emission of radiation
Henri Becquerel
studying uranium and discovered it spontaneously emits radiation
Marie Curie
with husband began experiments to isolate radioactive components of uranium
Ernest Rutherford
revealed three types of radiation: alpha, beta, gamma; "gold foil experiment"
"plum-pudding model"
J. J. Thomson proposed that the atom was a uniform sphere with embedded electrons
protons
positively charged particles in the nucleus
neutrons
neutral particles in the nucleus
James Chadwick
discovered neutrons
electronic charge
1.602 x 10⁻¹⁹ C; all charges of subatomic particles are represented as multiples of this charge
atomic mass unit
1.66054 x 10⁻²⁴ g = 1 amu
angstrom
A°, 10⁻¹⁰ m
atomic number
the number of protons in any element (subscript)
number of electrons
same as number of protons
mass number
total number of protons plus neutrons in an atom (superscript)
isotopes
atoms with identical atomic numbers but different mass numbers
average atomic mass
found using masses of isotopes and relative abundance on earth
metallic elements or metals
left side and middle of periodic table
nonmetallic elements or nonmetals
separated from metals by a diagonal step ladder in the periodic table
metalloids
lie along the line between metals and nonmetals in the periodic table
molecule
assembly of two or more atoms tightly bound together
chemical formula
shows the elements in the compound and the ratio of atoms
diatomic molecule
made up of two atoms
molecular compounds
composed of molecules of more than one type of element
molecular formulas
actual numbers and types of atoms in a molecule
empirical formulas
lowest ratio of elements in a molecule
structural formula
shows which atoms are attached within a molecule
ion
a charged particle
anion
negatively charged particle
cation
positively charged particle
polyatomic ions
consist of atoms joined as in a molecule with a net charge
ionic compound
compound that contains both positively and negatively charged ions
chemical nomenclature
system for names and formulas of compounds
hydrocarbons
only contain carbon and hydrogen
alkanes
hydrocarbons that contain carbon atoms that are bonded to four other atoms