| A | B |
|---|
| atom | fundamental unit of matter; made up of a nucleus of protons and neutrons and orbiting electrons |
| atomic number | number of an element; determined by the number of protons in its nucleus |
| atomic mass | the mass of the atom |
| bosons | sub-atomic particles of matter and energy |
| chemical formula | shorthand description of the moleculear make up of a compound |
| covalent bonds | when two or more atoms combine by sharing some of their valence electrons |
| electrons | negatively charged particles that orbit the nucleus of atoms |
| element | an atom with a unique number of protons |
| energy | work, or the capacity to do work |
| hydrogen | element with the atomic number of one; most common element in the universe; symbol of H |
| ion | an atom with more or fewer electrons than protons |
| isotopes | atoms that have more or less neutrons than protons |
| leptons | sub-atomic particles outside the nucleus of atoms--found in electrons. |
| matter | material that makes up objects; cannot be created nor destroyed |
| mass | total quantity of an object's matter |
| molecules | compounds made up of two or more atoms |
| neutron | part of the nucleus of atoms that have no electrical charge |
| noble gases | gases whose outer shells are full, making them extremely stable |
| nucleus | center of an atom |
| orbitals | shapes of the orbits of electrons |
| oxygen | an element with atomic number of eight and element symbol O |
| periodic table | arrangements of elements according to their atomic number and group |
| planetary model | theory that electrons circle the nucleus of atoms like orbiting planets |
| proton | positively charged part of the nucleus of atoms |
| quarks | sub-atomic particles of matter |
| shells | electrons orbit the nucleus of atoms in irregular patters called shells; quantum number |
| transuranium elements | elements with atomic numbers greater than 92; created under laboratory conditions |
| uncertainty principle | theory that it is impossible to know precisely the location of electrons |
| electron cloud model | shows electrons traveling in specific energy levels around a nucleus of protons and neutrons |
| average atomic mass | the weighted-average mass of an element's isotopes |
| mass number | the sum of protons and neutrons in the nucleus of an atom |
| groups (or families) | vertical columns in the periodic table that have elements with similar properties |
| periods | horizontal rows of elements that contain increasing numbers of protons and electrons |
| electron dot diagrams | use the element symbols and dots to represent outer energy level electrons |
| metals | any of various opaque, fusible, ductile, and typically lustrous substances that are good conductors of electricity and heat |
| metalloids | an element that has both metallic and nonmetallic properties, |
| non-metals | an element not having the character of a metal |
| atomic mass unit | a unit of mass for expressing masses of atoms, molecules, or nuclear particles equal to 1/12 the mass of a single atom of the most abundant carbon isotope |
