click below
click below
Normal Size Small Size show me how
8th- Atoms and PT
8th- Atomic Structure and the Periodic Table
| Term | Definition |
|---|---|
| atom | the smallest unit of an element |
| proton | a positively charged subatomic particle that is found in the nucleus and has a mass of 1 amu |
| neutron | a subatomic particle found in the nucleus that does not have an electric charge and has a mass of 1 amu |
| electron | a negatively charged subatomic particle that is found in the electron cloud surrounding the nucleus and has negligible mass |
| atomic mass | the sum of protons and neutrons in the atom |
| atomic mass unit (amu) | the unit in which the mass of one atom is expressed |
| isotope | an atom with a different number of neutrons and therefore a different atomic mass |
| electron cloud | the area around the nucleus where the electrons are; it is mostly empty space |
| orbitals | energy levels that electrons are arranged into |
| valence electrons | the electrons in the last shell that form chemical bonds with other atoms; they are responsible for giving the element its chemical properties |
| ion | an atom that has gained or lost an electron |
| compound | two or more elements bonded together |
| molecule | smallest piece of a compound |
| mixture | two or more substances physically combined |
| physical properties | describe traits or characteristics of matter, such as color |
| chemical properties | describes how an atom reacts or does not react to another |
| nucleus | what the center of an atom is called; where protons and neutrons are found |
| complete | describes an energy level or orbital that is full of electrons |
| atomic number | the name for the number of protons in an atom |
| period | a row in the Periodic Table |
| family | a group of elements with similar properties |
| neutral | overall charge of an atom |
| Lewis Structure | a diagram that includes only an element symbol and valence electrons |
| diatomic molecule | made of two identical atoms bonded together |
| pure substance | consists of only one kind of matter |
| element | the simplest form of matter |
| cation | an ion that has more protons than electrons, so it has a positive charge |
| anion | an ion that has more electrons than protons, so it has a negative charge |