| A | B |
|---|
| electron | the particle of an atom that moves rapidly in the space outside the nucleus |
| neutron | the particle of an atom that is neutral |
| proton | the particle of an atom with a positive charge |
| mass number | the sum of protons and neutrons in the nucleus of an atom |
| energy level | a specific amount of energy related to the movement of electrons in atoms |
| atomic number | the number of protons in the nucleus of every atom of an element |
| isotopes | atoms of the same element that differ in the number of neutrons, but have the same number of protons |
| nucleus | the very small center core of an atom |
| nuclear fusion | a process in which tow smaller atomic nuclei are forced together forming a larger nuclei |
| plasma | a gas-like state of matter consisting of free electrons and atomic nuclei |
| group | the vertical column on the periodic table that share similar characteristics |
| period | a row in the periodic table |
| atomic mass | the average mass of all isotopes of that element |
| periodic table | Mendeleev's arrangement of elements based on their properties |
| chemical symbol | an abbreviation for the name of an element that cont |
| corrosion | the reaction of a metal with oxygen to form rust |
| malleable | can be hammered into sheets and other shapes |
| reactivity | the ease and speed with which elements combine or react with other elements |
| conductivity | ability of a substance to transfer heat or electricity |
| ductile | can be drawn or pulled into a long wire |
| particle accelerator | a powerful machine that causes nulcear particles to collide and form larger nuclei |
| halogen | a family of very reactive elements whose atoms gain or share one electron |
| nonmetal | a type of element whose properties are generally opposite that of metals |
| semiconductor | material that conducts electricity under certain circumstances |
| metalloid | an element that has some characteristics of both metals and nonmetals |
| diatomic molecule | formed of two atoms |
| noble gas | unreactive elements |
| alph particle | two protons and two neutrons |
| radioactive decay | atomic nuclei of unstable isotopes release fast-moving particles and energy |
| radioactivity | spontaneous emission of radiation by unstable atomic nuclei |
| beta particle | fast-moving electron given off during radioactive decay |
| gamma radiation | high-energy waves that always accompany alpha and beta decay |
| tracer | used by doctors and industry to diagnose problems |
