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Chem Unit 2

Atoms composed of electrons, protons, and nuetrons
Molecules combinations of atoms
Ions changed particles
Aontoine Lavoisier: Law of Conservation of Mass or Matter (1790) Total mass remains constant during a chemical reaction; or total mas of reactants=total mass of products
Joseph Proust: Law of Constant Composition (law of definite properties) All samples of a compound have the same composition, or all samples have the same proportion by mass of the elements present.
Dalton's Atomic theory of Matter 1) all mater consists of small, indivisible particles call atoms 2) all atoms of a given element are alike but atom of any one element are different from the atoms of every other element.
Compounds formed when atoms of different elements unite in small whole number ratios (part of atomic theory of matter)
Chemical reactions involve rearrangments of atoms: no atoms are created, destroyed or broken apart in a chemical reaction-dalton say atoms are indvisible and indestructable
Law of Multiple Proportions: Dalton a given set of elements may combine to produce two or more different compounds, each with a unique compound.
Thomson 1897 Discovered electrons through experiments for conduction of electricity by gases at low pressures. led to plum pudding model
Robert MIllikan and oil drop experiment obtained the charge on an electron allowing the calculation of the mass of an electron
Rutherford and Gold Foil Experiments gold foil hit with "a" particles. Some deflected, led to discovery of nucleus w/ protons
Protons mass nearly equal to the H atom. Postive charge=negative electron charge in a nuetral atom
Nutrons (chadwick 1932) mass slightly greater than proton. help disperse the strong repulsion of positive charges
A mass number; protons + nuetrons
Z Atomic Number; number of protons
Isotopes atoms of the same element but different mass number. Boron -10: 10B 5 Boron -11: 11B 5
Ions atoms gain electrons to become negative ions or anoins. charge=p+ -e-
Atomic mass the relative mass of an atom compared to a standard (carbon-12). It is not equal to the mass number.
Isotopic Abundance the percent or fraction of each isotope found in nature.
Radioactive isotopes unstable and decay over time. They emit other particles and are transformed into other elements
Particles Emitted High speed electrons: B (beta) particles Helium nuclei: Alpha (a) particles High energy light: Gamma (y) particles
Metals shrink, smooth, solid at room temp, good conductor of heat and electricity, malleable (able to become sheet metal) and ducible (drawn into wire)
Metaloids physical and chemical properties of both metals and non-metals
Non-metals low melting and boiling points, brittle, dull-looking solids, porr conductors of heat and electricity
Mendeleev developed modern periodic table according to atomic weight. orgranized table to predict undiscovered elements
Periodic law element properties are periodic functions of their ATOMIC NUMBERS (not wieght)
Moseley arranged the periodic table in order of increasing atomic numbers
Molecule a group of two or more atoms held together ina definite shape by covalent bonds. (shared e-)
Empirical the simplest whole number ratio of elements ina compound. CH20
Molecular gives the ACTUAL number of each kind of atom in a molecule. C6H12O6
Structural show how atoms are attached to one another
Ions: cations positive ions
anions negative ions
Polyatomic a group of atoms w/ a charge
Ionic Compounds cations and anions, held together by electrostate attraction: formulas simplest ratio of numbers of atoms and represent one formula.
Created by: cnov232



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