| A | B |
|---|
| matter | anything that has mass and takes up space; a physical substance |
| pure substance | a material made of only one kind of element or compound; not a mixture |
| mixture | a physical combination of two or more substances. mixtures can be separated by physical means |
| state of matter | the physical form of matter described by its physical characteristics; the state of a pure substance largely depends on its temperature; matter can be a solid, liquid, gas, or plasma; pahse of matter is another term for state of matter |
| temperature | the hotness or coldness of a substance, stated in degrees; a measure of the average kinetic energy of the particles of a substance |
| solid | a rigid state of matter in which the particles align in a fixed arrangement; a solid substance has an unchanging shape and volume |
| liquid | a fluid state of matter in which the particles are free to move but are held close to each other; a liquid substance has an unchanging volume but a changeable shape |
| gas | a fluid state of matter in which the particles move so fast and are so far apart as to have little interaction with each other; gases have both a changeable shape and volume |
| plasma | a fluid state of matter made of extremely high-temperature ionized particles; plasmas have both a changeable shape and volume; since stars are made of plasma, it is the most common state of matter in the universe |
| melting | the change of state from a solid to a liquid at the melting point that is caused by adding energy; melting is the opposite of freezing |
| freezing | the change in state from a liquid to a solid caused by removing energy; freezing is the opposite of melting |
| vaporization | the change in state from a liquid to a gas caused by adding energy; vaporization is the opposite of condensation |
| boiling | the change of state from a liquid to a gas at the boiling point; boling is a form of vaporization that occurs when the pressure in the liquid exceeds the atmospheric pressure |
| evaporation | the change of state from a liquid to a gas below the boiling point but above the freezing point; evaporation is a form of vaporization that occurs when particles near the surface of the liquid gain sufficient energy to escape the liquid |
| condensation | the change in state from a gas to a liquid caused by removing energy; condensation occurs at the dew point and is the opposite of vaporization |
| sublimation | the change in state from a soild directly to a gas caused by adding energy; sublimation is the opposite of deposition |
| deposition | the change in state from a gas directly to a solid caused by removing energy; deposition is the opposite of sublimation |
| mass | the measure of the amount of matter in an object |
| weight | the force of gravitational attraction between an object's mass and its resident planet |
| volume | the amount of space that an object occupies |
| force | a push or pull on an object |
| gravity | the attractiove force between any two objects based on their masses; the strength of gravity decreases rapidly as the two objects move apart |
| work | work is done when a force acts on a moving object in the same or opposite direction of its motion or when energy is transferred from one object to another |
| energy | the ability to do work; energy exisits in many forms and can transfer between objects or change form |
| first law of thermodynamics | scientific law that states that matter and energy caanot be created or destroyed, but can only transfer between objects or transform to a different form; also called the law of conservation of matter and energy |
| atom | the smallest neutral particle of a element that retains the characteristics of that element; atoms are composed of a positive nucleus containing protons and usually neutrons, surrounded by negatively charged electrons |
| ion | a charged atom or group of atoms caused by a charge imbalance, which is produced by an unequal number of protons and electrons |
| element | a pure substance made of only one kind of atom |
| compound | a pure substance formed by chemically combining two or more elements |
| molecule | two or more chemically bonded atoms; molecules can be made of just one kind of element or a combination of elements |
| physical change | a change inmatter that doesn't alter its chemical identity; physical changes include changes of state, changing shape, polishing, dissolving, etc. |
| chemical change | the change from one pure substance to another by the rearrangement of atoms in a chemical reaction; we typically recognize chemical changes by a change in color, change in energy, formation of a gas, and/or formation of a solid |
| nuclear change | a change of one element into another element by changes occurring in the nucleus of the atom; nuclear changes can occur when atoms emit or absorb rays or particles; it can also occur in nuclear reactions when atoms split apart through fission or join together through fusion |
