| A | B |
|---|
| Proton | Positively charged particle that exists in the nucleus of an atom |
| Neutron | Particle with no charge that exists in the nucleus of most atoms |
| Electron | Negatively charged particle that exists in the space surrounding an atom's nucleus |
| Subatomic Particles | particles that are smaller than an atom containing protons, neutrons, and electrons. |
| Nucleus | the center core of an atom that contains protons and neutrons. |
| Atomic Number | the number of protons that an atom contains in the nucleus. |
| Strong Nuclear Force | The reason that an atom's protons don't break it's nucleus apart |
| Energy Levels | a region around the nucleus of an atom where electrons are most likely to be found.Each period (row) of the periodic table indicates specific levels which contain electrons. |
| Atomic Mass | average of all known isotopes for particular element. |
| Atomic Mass Unit | Equal to 1/12th the mass of a carbon-12 atom |
| Group of Elements | Elements with similar properties, listed in a single column on the periodic table |
| Periodic Table | A chart of the elements, arranged to provide information about each element's behavior |
| Chemical Symbol | The abbreviation for the name of an element |
| Mass Number | The total number of protons and neutrons in the nucleus of an atom |
| Isotope | forms of the same element that have different numbers of neutrons and different mass numbers.U235 is a wellͲknown one. |
| Periodic Table of Elements | visually organizes the similarities between all known elements.Elements are listed by atomic number. |
| Element | substances that contain only one kind of matter.2 or more make up a compound.The periodic table lists them by atomic number. |
| Noble Gases | – Elements in Group 18 of the periodic table.Inert gases with completely filled valance shells.Stable and do not bond well with other elements. |
| Valance Shell | the outermost region of the electron cloud. |
| Electron Cloud Model | identified by Erwin Schrodinger through quantum mechanics.This is the latest model of Atomic Theory representing the probability of electron position. |
| Strong Nuclear Force | works over a short distance; a force greater than gravity that holds the nucleus of an atom together. |
| Compound | substances made of two or more elements that cannot be separated by physical means.(CO2 or H2O are examples) |
| Mass Number | the total number of protons and neutrons in the nucleus of an atom. |
| Ion | charged atom that has gained or lost electrons. |
