| A | B |
|---|
| molecule | The smallest unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound. |
| mixture | Two or more substances that are not chemically united and that exist in no fixed proportion to each other. |
| proton | A positively charged part of an atom found in the nucleus |
| neutron | A neutral part of an atom, found in the nucleus of all atoms, except hydrogen. |
| electron | A negatively charged part oa an atom, found circling around the nucleus. |
| nucleus | A positively charged area within an atom, composed of neutrons and protons, and possessing almost all of the mass of the atom, but occupying only a small fractgion of the volume of the atom. |
| ion | An electrically charged atom formed by the loss or gain of one or more electrons |
| compound | A particle composed of two or more elements. |
| matter | Anything that has mass and takes up space. |
| isotope | One of two or more atoms having the same atomic number but different mass numbers. |
| core | The central portion of the earth, believed to be composed mainly of iron & nickel in a molten state. |
| mantle | The portion of the earth, between the crust and core. |
| crust | The outer layer of the earth, about 22 miles deep under the continents and 6 miles deep under the oceans. |
| sedimentary rock | Rock that has been formed through the deposition & solidification of sediment. These are often deposited in layers, and frequently contain fossils. |
| igneous rock | Rock formed by the solidification of molten magma. |
| metamorphic rock | Rock that was once one form of rock but has changed to another under the influence of heat and/or pressure. |
| weathering | Various mechanical and chemical processes that cause exposed rock to decompose. |
| stalactite | A deposit, usually of calcium carbonate, shaped like an icicle, hanging from the roof of a cave. |
| stalagmite | A deposit, usually of calcium carbonate, resembling an inverted stalactite, formed on the floor of a cave. |
| geology | The science that deals with the dynamics and physical history of the earth. |
