Chem Sem 2

vocab

valence electron

electrons in the outermost energy level

oxidation number

a number that represents the number of electrons gained or lost by an atom or group of atoms

atomic radius

 the distance from the nucleus to the outer edge of the electron cloud

ionization energy

energy required to remove an electron from a gaseous atom

polar covalent bond

bond in which electrons are not shared equally

molar mass

mass of one mole (units g/mole), found on PT

molecule

two or more atoms held together by covalent bonds, smallest individual particle of a molecular compound

cation

positive ion

solute

substance that is dissolved in a solution

products

formed as a result of a chemical reaction

chemical formula

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expression that use the atomic symbol to indicate the type of atoms or ions present and subscripts to indicate how many atoms or ions are present

mole

metric unit used to measure the amount of a substance; one mole is the amount of a pure substance that contains 6.02 x 1023 particles (atoms, ions, molecules or formula units)

electronegativity

 indicates the relative ability of an element’s atoms to attract electrons in a chemical bond

ionic bond

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bond in which electrons are ***transferred***, ions are held together by the attraction between opposite charges

VSEPR Theory

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 bonds and unshared pairs are oriented around the central atom so that the electrons are oriented as far apart as possible

formula unit

lowest whole number ratio of ions represented in an ionic compound 

octet rule

atoms will gain, lose or share electrons to achieve the electron configuration of the nearest noble gas

solvent

able to dissolve solutes in a solution

single replacement

chemical reaction that occurs when the atoms of one element replace the atoms of another element in a compound

chemical reactivity

the tendency of a substance to lose, gain or share electrons in a system

dipole

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region in a molecule with an excess or lack of electrons

empirical formula

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a chemical formula that shows the smallest whole number ratio of the elements in a compound 

nonpolar covalent bond

bond in which electrons are being shared equally

molecular formula

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a chemical formula that specifies the __actual__ number of atoms of each element in a molecule

anion

negative ion

stoichiometry

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the study of quantitative relationships between the amounts of reactants used and products formed by a chemical reaction

solution

mixture of solvent (normally water) and a solute

reactants

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starting substance in a chemical reaction

double replacement

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a chemical reaction that involves the exchange of positive ions between two compounds and produces either a precipitate, a gas or water

chemical equation

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statement using chemical formulas to describe the identities and relative amounts of the reactants and products involved in the chemical reaction