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Chem exam 2
| Question | Answer |
|---|---|
| polar covalent bond | covalent bond between 2 atoms with significantly different electronegatives resulting in uneven distribution of electron density |
| electronegativity | the ability of an atom to attract electrons to itself in a covalent bond |
| increases | the electronegativity ______________ across the periodic table |
| decreases | the electronegativity _____________ down the periodic table |
| nonpolar covalent bond | difference in electronegativity is small |
| ionic bond | difference in electronegativity is large |
| EN 0-0.4 | nonpolar covalent |
| EN 0.4-2 | polar covalent |
| EN 2.0 | ionic |
| dipole moment | a measure of the seperation of positive and negative charge in a molecule |
| distance and magnitude | the dipole moment is dependent on ______ and _______ |
| percent ionic character | ratio of a bonda actual dipole moment to the dipole moment it would have if the electrons were completely transfered from one atom to another |
| resonance structure | one of two or more avlid lewis structures shown with double headed arrows between them to indicate that the actual structure of the molecule is intermediate between them |
| resonance hybrid | the actual structure of a molecule that is intermediate between 2 or more resonance structures |
| formal charge | fictitious charge assigned to each atom in a lewis structure if all bonding electrons were shared equally |
| zero | the sum of all formal charges in a neutral molecule must be _____ |
| ion | the sum of all formal charges in an _____ must equal the charge of the ______ |
| small, large | ______ formal charges on indivdula atoms are better than ______ one |
| electronegative | when formal charges cant be avoided, negative formal charges should reside on the most ______ atom |
| free radicals | a molecule or ion with an odd number of electrons in its lewis structure |
| boron | expanded octets happens with _______ |
| third | expanded octets happen with the _____ row of the periodic table and beyond |
| bond energy | for a chemical bond, the energy required to break 1 mol of the bond in the gas phase |
| bond length | the average length of a bond between 2 particular atoms |
| weaker | the longer the bond, the ______ the bond |
| VSPER | a theory that allows the prediction of the shapes of molecules based on the idea that electrons repel one another |
| electron groups | a general term for lone pairs, single bonds, multiple bonds and lone electrons in a model |
| seperation | preferred geometry is maximum _________ |
| number, bonding | geometry depends on - ______ of electron groups around the central atom - how many _______ vs lone pairs |
| 2 | electron groups in linear electron geometry |
| 3 | electron groups in trigonal planar electron geometry |
| 4 | electro groups in tetrahedral electron geometry |
| smaller | the more lone pairs the bonds get progressively __________ |
| polar | any atom with lone pairs is going to be ________ |
| most repulsive | lone pair- lone pair |
| least repulsive | bonding pair-bonding pair |
| chemical change | a change that alters the molecular composition of a substance |
| physical change | a change that alters the state of appearance of a substance but not its chemical composition |
| chemical property | a property that a substance displays only by changing the chemical composition |
| physical property | a property that a substance displays without changing chemical composition |
| chemical equation | representation of a chemical reaction; contains an equal number of atoms on either side of the equation |
| reactants | starting substances in a chemical reaction |
| products | substances produced in a chemical reaction |
| combustion reaction | CxHx + O2 ----> CO2 + H20 |
| stoichiometry | the numerical relationship between amounts of reactants/products in a balanced chemical equation |
| mole to mole ratio | the key in stoichiometry |
| solution | homogenous mixture of 2 substance |
| solvent | the majority component of a solution |
| solute | the minority component of a solution |
| aqueous solution | water acts as the solvent |
| dilute solution | a solution that contains a very small amount of a solute relative to the amount of the solvent |
| concentrated solution | a solution contains a large amount of solute relative to the amount of solvent |
| molarity | concentration; moles of solution per liter |
| stock solution | a highly concentrated form of a solution used in labs to make less concentrated solutions via dilution |
| electrolytes | a substnace that dilutes in H2O to form solutions that conduct electricity |
| strong electrolytes | a substance that completely dissolves into ions when disolved into water |
| nonelectrolytes | a compound that doesnt dissociate into ions when dissolved in water |
| acids | ionize to form H+ when in water |
| strong acid | an acid that completely ionizes in a solution |
| weak acids | an acid that doesn't completely ionize in H2O |
| weak electrolytes | a substance that doesnt completely ionize in water, only weakly conducts electricity |
| soluble | describes a compound that is able to dissolve a significant extent, usually in h2O |
| insoluble | incapable of dissolving in H2O or is extremely difficuly to dissolve H2O |
| precipitate | a solid, insoluble, ionic compound that forms in seperate fro a solution |
| precipitate reaction | reaction in which a solid, insoluble product forms upon mixing two solutions |
Created by:
alexiarecinella
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