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Chemistry Unit 2
Question | Answer |
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atomic mass | The weighted average of the relative masses of all the isotopes of an element |
atomic number | an identifying number for each element that is equal to the number of protons in the nucleus of an atom of that element. |
chemical property | any characteristic of a chemical compound that uses element symbols and subscripts to indicate the number of each kind of atom in a chemical compound |
chemical reaction | a chemical change in which one or more substances change into new substances with different properties |
compound | a pure substance made up of two or more elements chemically combined in definite proportions |
element | a pure substance that cannot be broken down into simpler substances by chemical or physical means |
extensive properties | physical properties of matter that depend on the amount of matter present |
intensive properties | physical properties of matter that do not depend on the amount of matter present |
isotope | an atom of a particular element with the same number of protons but a different number of neutrons |
law of conservation of mass | a scientific law which states that matter is neither created nor destroyed in a chemical reaction |
mass number | the number of protons plus the number of neutrons in the nucleus of an atom |
matter | anything that has mass and takes up space |
mixture | a combination of two or more pure substances, each of which maintains its individual chemical properties and can be separated by physical means |
physical change | a change in a substance that does not involve a change in its composition |
physical property | a characteristic of a substance that may be observed or measured without changing the composition of the substance |
polar molecule | a molecule with a slightly positive charge on one side and a slightly negative charge on the other side |
product | a substance obstained from another substance in a chemical reaction |
pure substance | matter that has a uniform composition and properties throughout |
reactant | any substance that undergoes chemical change in a chemical reaction |
solvent | the component in which a solute is dissolved to form a solution |
thermal conductivity | the ability of a material to conduct heat |
dehydration reaction | a chemical reaction in which hydrogen and oxygen molecules are removed from the reactants to produce water |
electrolysis | a chemical reaction that occurs when an electric current is passed through an electrolyte to bring about a decomposition reaction |
inorganic compound | any compound except a carbon oxide, a carbide or a carbonate that does not contain the element carbon |
organic compound | any compound except a carbon oxide, carbide or carbonate that contains the element carbon |
law of definite proportions | a scientific law which states that a chemical compound will always contain the same elements in the same definite proportions by mass regardless of the size of the sample |
law of multiple proportions | a scientific law which states that when more than one compound is formed by different combinations of the same elements, the different masses of one element that combine with the same mass of a second element will form ratios of small whole numbers. |
adhesion | the intermolecular force of attraction of the particles of one substance for the particles of a different substance at the point of contact |
alloy | a solution formed by dissolving a metal in a metal or a non-metal in a metal while the components are molten (melted) |
capillarity | the distortion, elevation or depression of the surface of a liquid due to the adhesion of its surface particles to the particles of the solid containing the liquid; also known as capillary action |
centrifuge | a device that rotates a sample at high speeds, causing the components of a mixture to separate |
chromatography | a method of separating a mixture into its components based on the adhesion rate of the individual components to a stationary phase |
colloid | a mixture consisting of particles larger than 1 nm but smaller than 1000 nm suspended in a dispersal medium |
distillation | the process of physically separating a single-phase mixture into components if the components have different boiling points |
filtration | the process of separating a solid phase from a fluid phase in a mixture by passing the mixture through a porous barrier that traps the solid |
fractional crystallization | a method of separating a mixture of two solids that are both soluble in the same solvent but have different rates of solubility |
fractional distillation | the separation of a mixture of liquids in which the components, called fractions, each have a different boiling point |
heterogeneous mixture | a mixture in which the individual components remain distinct in separate phases without a uniform consistency |
homogeneous mixture | a mixture in which the components form a single phase with a uniform consistency |
mobile phase | a solution composed of the components of a mixture dissolved in a solvent to be separated by chromatography |
phase | a homogeneous region within a heterogeneous system |
solubility | the amount of solute that will dissolve in a solvent at a given temperature and pressure |
solute | the component being dissolved in a solvent to form a solution |
solution | a homogeneous mixture in which a solute is dissolved in a solvent; particles in a solution are less than 1 nanometer in diameter |
suspension | a heterogeneous mixture in which particles are not uniformly distributed throughout the mixture and will settle out unless it is constantly agitated; particles in a suspension are larger than 1000 nanometers in diameter |
stationary phase | the substance used to separate the components in chromatography |