| Term | Definition |
| chemistry | The science that deals with the materials of the universe and the changes these materials undergo |
| measurement | observations that involve a number and unit |
| scientific method | a pattern of investigation procedures |
| bias | occurs when a scientist's expectations change how the results are analyzed or how the conclusions are made |
| theory | explanation based on repeated observations and investigations |
| natural law | a statement about what happens that seems to be true all of the time |
| experiment | a method of collecting data to test a hypothesis |
| matter | the stuff that the universe is made of |
| atom | a fundamental unit of which elements are made |
| element | only one type of atom |
| allotrope | the same element, but with a different physical form |
| compound | atoms of different elements that form a new substance |
| molecule | a collection of atoms bonded together that behave as a unit |
| physical change | does no effect the composition |
| chemical change | when a new substance is formed |
| mixture | substances added together without chemical change |
| alloy | a solid mixture with metallic properties |
| pure substance | either a pure element or compound |
| homogeneous mixture | a mixture that is the same throughout |
| heterogeneous mixture | a mixture with regions of different properties |
| distillation | separation process that depends on the different boiling points of the substances |
| filtration | separating by using filter paper |
| law of constant composition | a given compound always contains the same proportion of elements |
| the Rutherford experiment | discovered that the atom is mostly empty space |
| valance electrons | electrons in the outer level or sub level that are involved in reations |
| atomic numer | the number of protons |
| atomic mass | the number of protons and neutrons |
| isotope | the same element but with a different number of nuetrons |
| average atomic mass | the average mass of all the isotopes of an element |
| half life | the amount of time it takes for half of a sample of an isotope to break down into other elements |
| carbon dating | using the decay of C-14 to determine the age of organic substances |
| families | columns on the Periodic table |
| periods | rows on the Periodic table |
| electron dot structure | a shorthand method of showing the number of valance electrons |
| ion | an atom that has gained or lost electrons |
| oxidation number | the charge of an ion |
| chemical bond | the force that holds atoms together in a compound |
| ionic bond | where electrons are transferred, creating opposite charges which attract |
| chemical formula | indicates the elements in a compound and the ratio of the elements |
| binary 1 compound | includes two elements, an A group metal and nonmetal |
| binary 2 compound | includes a transition metal and nonmetal |
| binary 3 compoud | includes two nonmetals |
| polyatomic ion | a group of charged atoms that act as a single ion |
| acid | a substance that donates a hydrogen ion |
| standard | the exact quantity that people use to compare measurements |
| length | straight line distance between two points |
| mass | the amount of matter in an object |
| volume | amount of space occupied by an object |
| density | the mass per unit volume of a material |
| temperature | the average kinetic energy of all particles in an object |
| scientific notation | the shorthand method of reporting large and small numbers |
| accuracy | the degree to which a measurement agrees with the actual value |
| precision | the refinement in a measurement |
| significant figures | those digits that carry meaning and contribute to precision |
| molar mass | the mass of 1 mole of a sbustance |
| percent composition (by mass) | the percent of the mass a compound makes up in an element |
| empirical formula | the smallest whole number ratio of elements in a compound |
| molecular formula | a formula of a compound that indicates the true number of the atoms of each element |
| hydrate | a compound with water chemically attached to it |
| chemical reaction | a well-defined example of a chemical change |
| strong electrolyte | completely splits apart in a solution |
| nonelectrolyte | has no ions and doesn't split in a solution |
| molecular equation | equation where all species are listed as molecules |
| complete ionic equation | equation where all ions are included before and after |
| net ionic equation | equation that removes all spectator ions |
| synthesis | a reaction where two or more substances combine to form a new, simpler substance |
| combustion | a reaction where CO2 and H2O are formed |
| decomposition | a reaction where one substance breaks into two or more simpler substances |
| single-displacement | a reaction where one element replaces another in a compouund |
| acid- base reactions | a reaction where H2O and a salt are formed |
| oxidation-reduction | a reaction where electrons are transferred |
| oxidized | becomes more positively charged |
| reduced | becomes more negatively charged |
| salt | an ionic compound whose cation comes from a base, and anion from an acid |
| double-displacement | a reaction where a precipitate, water, or gas is formed when two ionic compounds in a solution are combined |
| activity series | a list of metals arranged in decreasing ease of oxidation |
