Question | Answer |
Compound | a substance made of two or more kinds of atoms that are chemically combined |
Chemical change | a change in the composition of a substance; a rearrangement of the atoms into a new substance |
Chemical properties | ability to form new substances |
Elements | substances containing only one type of atom |
Matter | has mass and occupies space. |
Physical change | a change in which the composition of the substance is not altered |
Chemical reactions | another term for chemical changes |
Law of constant composition | the number of atoms in a molecule or compound is always the same; e.g. water is always two hydrogens and one oxygen |
Alloy | A substance that contains a mixture of elements and has metallic properties. |
Atom | the fundamental unit of which elements are composed; the smallest sample of an element that has all the properties of that element, generally composed of the three subatomic particles (electrons, protons, and neutrons). |
Chemical change | the change of substances into other substances through a reorganization of the atoms; a chemical reaction. |
Chemical properties | Exhibited by matter as it undergoes changes in composition; The ability of a substance to change to a different substance. |
Chromatography | Any of various techniques for the separation of complex mixtures that rely on the differential affinities of substances for a gas or liquid mobile medium and for a stationary adsorbing medium through which they pass, such as paper, gelatin, or magnesia. |
Compound | A pure substance with constant composition that can be broken down into elements by chemical processes. |
Density | A property of matter representing the mass per unit volume. Density is a derived unit. |
Distillation | -a method for separating the components of a liquid mixture that depends on differences in the ease of vaporization of the components. |
Elements | A pure substance that cannot be decomposed into simpler substances by chemical or physical means. It consists of atoms all having the same atomic number. |
Extensive properties | A non inherent property of a system, such as volume or internal energy, that changes with the quantity of material in the system; the quantitative value equals the sum of the values of the property for the individual constituents |
Filtration | A method for separating the components of a mixture containing a solid and a liquid. |
Intensive properties | properties independent of the quantity or shape of the substance under consideration; for example, temperature, pressure, or composition. |
Gas | One of the three states of matter; has neither fixed shape nor fixed volume |
Heterogeneous mixture | A mixture that has different properties in different regions of the mixture. |
Homogeneous mixture | A mixture that is the same throughout; a solution. |
Law of conservation of energy | energy can be converted from one form to another but can be neither created nor destroyed. |
Law of definite composition | Also known as the Law of Constant Composition; The law that a given chemical compound always contains the same elements in the same fixed proportion by weight. |
Liquid | one of the three states of matter; has a fixed volume but takes the shape of its container. |
Matter | The material of the universe; anything that has mass and occupies space. |
Mixture | A material of variable composition that contains two or more pure substances. Each component in the mixture retains its own properties. |
Molecule | a bonded collection of two or more atoms of the same element or different elements. |
Physical change | a change from one state (solid or liquid or gas) to another without a change in chemical composition |
Physical properties | A characteristic of a substance that can be observed in the absence of change; that is, without the substance becoming a different substance. |
Pure substances | A substance with constant composition. |
Reaction | a change or transformation in which a substance decomposes, combines with other substances, or interchanges constituents with other substances |
Solid | one of the three states of matter; has a fixed shape and volume. |
Solution | a homogeneous mixture. |
States of matter | The three different forms in which matter can exist: solid, liquid, and gas |
Trace elements | Elements required in living systems, found in very small quantities. |