| A | B |
|---|
| Chemical Symbol | A shorthand way to write the name of an element |
| Nucleus | The positively charged center of an atom |
| Electron | A negatively charged particle that orbits around the nucleus of an atom |
| Proton | A particle in the nucleus of an atom that has a positive charge |
| Neutron | A particle in the nucleus of an atom that has no electrical charge |
| Atomic Number | The number of protons in an atom's nucleus |
| Electron Cloud | The space where electrons most probably exist around the nucleus of an atom |
| Quarks | A very small particle of matter that makes up protons and neutrons |
| Mass Number | Total particles in an atom's nucleus |
| Isotopes | Atoms of the same element that have different numbers of neutrons |
| Periodic Table | A table of the elements, in order by increasing atomic mass, arranged in rows and columns to show their repeated properties |
| Group | One of the 18 vertical columns in the periodic table |
| Dot Diagram | A diagram of an atom, using the element symbol with dots to show the electrons in the outer energy level |
| Period | A horizontal row of elements in the periodic table; increasing from left to right is the number of electrons in the atoms' outer shell |
| Metals | An element usually having the following characteristics: shiny, ductile, and a good conductor of heat and electricity |
| Nonmetal | An element that usually lacks the characterics of a metal |
| Metalloid | An element having some properties of both a metal and a nonmetal |
| Average Atomic Mass | The average mass of the mixture of isotopes that occur in nature for an element |
| Diatomic Molecule | A molecule composed of two atoms of the same element |
| Ductile | Able to be drawn out into a wire |
| Malleable | Able to be hammered or rolled into thin sheets |
| Radioactive Element | An unstable element whose nucleus breaks down and gives off particles, radiation, and energy |
| Sublimation | The phase process in which a solid changes directly to a gas/vapor without forming a liquid |
| Transition Element | Located in Groups 3-12 of the periodic table |
| Transuranium element | Any element having more than 92 protons, the atomic number of uranium |
