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Elements&PerodicTabl
| Term | Definition |
|---|---|
| atom | The basic particle from which all elements are made; the smallest particle of an element that has the properties of that element. |
| electron | A tiny, negatively charged particle that moves around the outside of the nucleus of an atom. |
| nucleus | The central core of an atom which contains protons and neutrons. |
| proton | Small, positively charged particles that are found in the nucleus of an atom |
| energy level | A region of an atom in which electrons of the same energy are likely to be found. |
| neutron | A small particle in the nucleus of the atom, with no electrical charge. |
| atomic number | The number of protons in the nucleus of an atom. |
| isotope | An atom with the same number of protons and a different number of neutrons from other atoms of the same element. |
| mass number | The sum of protons and neutrons in the nucleus of an atom. |
| atomic mass | The average mass of all the isotopes of an element. |
| periodic table | An arrangement of the elements showing the repeating pattern of their properties. |
| chemical symbol | A one-or two- letter representation of an element. |
| period | A horizontal row of elements in the periodic table. |
| group | Elements in the same vertical column of the periodic table; also called family. |
| metal | A class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity. |
| luster | The way a mineral reflects light from its surface. |
| malleable | A term used to describe material that can be hammered or rolled into flat sheets. |
| ductile | A term used to describe a material that can be pulled out into a long wire. |
| thermal conductivity | The ability of an object to transfer heat. |
| electrical conductivity | The ability of an object to carry electric current. |
| reactivity | The ease and speed with which an element combines, or reacts, with other elements and compounds. |
| corrosion | The gradual wearing away of a metal element due to a chemical reaction. |
| alkali metal | An element in Group 1 of the periodic table. |
| alkaline earth metal | An element in Group 2 of the periodic table. |
| transition metal | One of the elements in Groups 3 through 12 of the periodic table. |
| nonmetal | An element that lacks most of the properties of a metal. |
| diatomic molecule | A molecule consisting of two atoms. |
| halogen | An element found in Group 17 of the periodic table. |
| noble gas | An element in Group 18 of the periodic table. |
| metalloid | An element that has some characteristics of both metals and nonmetals. |
| semiconductor | A substance that can conduct electric current under some conditions. |