| A | B |
|---|
| atomic number | the number of protons in an atom |
| isotopes | atoms of the same element that have different numbers of neutrons |
| mass number | the sum of the neutrons and protons in the nucleus of an atom |
| element | substance that cannot be broken down into simpler substances |
| electron | negatively charged particles that exists in an electron cloud formation around an atom's nucleus |
| proton | positively charged particle in the nucleus of an atom |
| neutron | electrically neutral particle that has the same mass as a proton and is found in an atom's nucleus |
| electron cloud | region surrounding the nucleus of an atom, where electrons are most likely to be found |
| malleable | property of metals that allow them to bend |
| energy level | area around the nucleus that contains the electrons |
| protons and neutrons | located in the nucleus |
| nucleus | center part of the atom that contain the mass of the atom |
| symbol | one or two letters that represent an element |
| neutral | normal charge of all atoms on the periodic table |
| balanced equation | when the atoms of the right side equal the elements on the left side of an equation |
| reactants | atoms on the left side of an equation |
| products | the atoms on the right side of the equation |
| element | identified by only one capital letter |
| atom | smallest part of an element |
| molecule | two or more atoms joined together, smallest part of a compound |
| compound | two or more different atoms combined |
| family or group | vertical column of the periodic table, each has the same characteristics |
| period or energy level | rows of the periodic table |
| alkali metals | 1st column of the periodic table, very reactive |
| alkali earth metals | second column of the periodic table |
| halogens | second to last column of the periodic table |
| nobel gasses | last column of the periodic table, these don't react with other elements, inert |
