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 matter | anything that occupies space and has mass |
| element | a pure substance that cannot be broken down into other substances by chemical means |
| trace element | elements that make up less than 0.01 percent of your body mass |
| compound | a substance containing two or more elements that are chemically combined in a fixed ratio |
| atom | smallest possible particle of an element |
| proton | subatomic particle with a single unit of positive electrical charge, + |
| electron | subatomic particle with a single unit of negative electrical charge, - |
| neutron | subatomic particle that is electrically neutral |
| nucleus | central core of atom |
| atomic number | number of protons in a particular element |
| isotope | alternate form of an element; have same number of protons in their atoms but different numbers of neutrons |
| radioactive isotope | isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy |
| ionic bond | type of chemical bond that occurs when an atom transfers an electron to another atom |
| ion | atoms (or groups of atoms) that have become electrically charged as a result of gaining or losing electrons |
| covalent bond | forms when two atoms share electrons |
| molecule | two or more molecules held together by covalent bonds |
| chemical reaction | breaking of old and formation of new chemical bonds that result in new substances |
| reactant | starting materials for the chemical reaction |
| product | material created as a result of a chemical reaction |
| polar molecule | a molecule in which opposite ends have opposite electric charges |
| hydrogen bond | bond created by weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule |
| cohesion | the tendency of molecules of the same kind to stick to one another |
| adhesion | type of attraction that occurs between unlike molecules |
| thermal energy | total amount of energy associated with the random movement of atoms and molecules |
| temperature | measure of the average energy of random motion of the particles in a substance |
| solution | a uniform mixture of 2 or more substances |
| solvent | the substance that dissolves the other substance and is present in the greater amount (example - water) |
| solute | the substance that is dissolved and is present in a lesser amount (example - salt: salt dissolves in water) |
| aqueous solution | when water is the solvent, the result is called this |
| acid | a compound that donates H+ ions to a solution |
| base | a compound that removes H+ ions from an aqueous solution |
| pH scale | describes how acidic or basic a solution is: ranges from 0 (most acidic) to 14 (most basic) |