Term | Definition |
atom | Smallest particle of an element that has the properties of that element |
molecule | the particle of a kind of compound (ex.: H2O) |
element | Substance with a single kind of atom; ex. O2 (oxygen) |
property | Describes a substance or object |
closed system | Nothing gets in or out -- like a closed box or balanced equation. |
conservation of matter | Stuff doesn't go away, and it doesn't come from nowhere. |
physical change | A change in some description (property) for a substance, but it remains the same substance |
density | The amount of matter in a given volume: D=m/v |
temperature | A measurement of the average thermal energy (commonly called "heat") in a substance |
mixture | Two or more substances combined (Do not confuse with compound.) |
compound | A particle (molecule or ionic) made of two or more elements (Do not confuse with mixture.) |
volume | Measures how much space the object takes up, given in cubic units or liters |
chemical change | When a substance becomes new substance(s) with new properties |
matter | Anything that has volume and mass |
characteristic property | Description for a substance that could identify the substance, no matter how much you had |
substance | Matter of all one kind of particle, and with specific properties |
mass | A measurement of the amount of matter in an item; does not change with gravity |
weight | A measure of the force of gravity on an item; do not confuse with mass |
heat | a transfer of thermal energy from a warmer object to cooler one (and ALWAYS in that direction) |
solid | particles close together, vibrating in place; may be formed from molecules or crystals |
liquid | particles close together like solid but can change relative position |
gas | particles widely spaced and moving freely |
endothermic | reaction in which products store energy in chemical bonds from surroundings, having more stored energy than the reactants; detected as decrease in temperature |
exothermic | reaction in which products release energy from chemical bonds to surroundings, having less stored energy than the reactants; detected as increase in temperature |
reactants | the starting substances in a chemical change |
products (chemical change) | the resulting substances from a chemical change |