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Chem Unit 2
Question | Answer |
---|---|
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. |