chem study guide

chem study guide - Chemistry Study Guide Chapter 1 and 2-...

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Unformatted text preview: Chemistry Study Guide Chapter 1 and 2- King Derek Can Make Nothing Kilo, Deci, Centi, Milli, Nano 3, -1, -2, -3, -9- Law of definite proportions: all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements- Law of multiple proportions: when two elements (A and B) form two different compounds, the masses of element B that combine with 1 gram of element A can be expressed as a ratio of small whole numbers- John Daltons Atomic Theory 1. Each element is composed of tiny indestructible parts called atoms 2. Atoms of the same element have the same mass and other properties 3. Atoms combine in simple whole number ratios to form compounds 4. Atoms of one element cannot change into atoms of another element, they can only change the way they bind to other atoms- Cathode ray experiment: discovery that electrons exist and are negatively charged o Cathode rays travel in straight lines from the negative end of the cathode ray to tube to the positive end, independently of the material they came from (because they carry an electrical charge) o Electrical charge results in attractive and repulsive forces (electrostatic forces) o Because charge-to-mass ratio is smaller than smallest atom, deduced that atom is destructible; can be broken down into individual electrons- Oil drop experiment: discovery of the charge of the electron o Charge on oil droplets falling in an electric field calculated; since lower plate was negatively charged, and since strength of electric field could be varied, free fall of negatively charged particles could be slowed and then reversed- Gold Foil Experiment: discovery that all positive charge and most mass of an atom is concentrated in the center of the atom- the nucleus o Expected alpha particles to pass through gold foil undeflected because of plum pudding model; found that most passed through but some deflected at large angles- Plum pudding model: negatively charged electrons are held in a positively charged sphere- Nuclear Theory 1. Most of atoms mass and all of its positive charge is contained in the nucleus 2. Most of the atoms volume is empty space where electrons are dispersed 3. Number of protons and neutrons is equal, so atom is electrically neutral Proton 1 amu +1 Nucleus Neutron 1 amu Nucleus Electron 0 amu-1 Outside nucleus- Proton + neutron= mass number- Number of protons = atomic number- Neutrons= mass number- atomic number/protons- Electrons= atomic#/protons- charge- Atoms of an element that have different numbers of neutrons (and different masses) are isotopes- Atoms that have lost or gained electrons become charged and are cations/anions- Average atomic mass= sum of: (fractional abundance [%/100]* isotope mass) Chapter 3- Ionic bond: transfer of electrons from one atom to another; metal and nonmetal o Left atom: element name o Right atom: ends in ide o Memorize polyatomic ions- As you remove electrons, there are more protons holding the electrons there...
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This note was uploaded on 04/19/2011 for the course CHEM 131C taught by Professor Blogh during the Spring '10 term at Maryland.

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chem study guide - Chemistry Study Guide Chapter 1 and 2-...

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