| A | B |
|---|
| protons | postive charge, found in nucleus, defines the element |
| neutrons | no charge, found in the nucleus |
| electrons | negative charge, found around the nucleus |
| nucleus | center of the atom |
| Atomic number | number of protons (or electrons) in an atom |
| Niels Bohr | developed the plantary model of the atom |
| Electron Cloud Model | current model of the atom, electrons move too fast to be sure of exact location in the electron cloud |
| Heisenberg Uncertainty Principle | Electrons' location and velocity can't be determined at the same time |
| 1st energy level | holds 2 electrons |
| 2nd energy level | holds 8 electrons |
| 3rd energy level | holds 18 electrons |
| 4th energy level | holds 32 electrons |
| Quarks | smaller particles that make up protons and neutrons |
| Photons | no-mass particles that make up light when they are released from the atom |
| antiproton | same as a proton but negatively charged |
| Positron | same as an electron, but positively charged |
| Atomic Mass Unit | the mass of one proton or one neutron |
| Mass number | sum of the protons and neutrons in an atom |
| Isotopes | atoms of the same element that have different numbers of neutrons |
| Average Atomic Mass | average of the mass of all the isotopes in a sample of a particular element |
| Mendeleev | Russian chemist that developed the periodic table, ordered by atomic masses |
| Modern Periodic Table | arranged by atomic numbers and properties |
| groups | vertical columns on the PT (1-18), tell you how many electrons ar ein the outer energy levels |
| periods | horizontal rows of the PT (1-7), tell you how many energy levels are in the atom |
| Metals | left side of the PT |
| Non-metals | right side of the PT |
| Metalloids | along the stairstep line, have properties of both metals and non-metals |
| Transition elements | groups 3-12 |
| Particle accelerator | shoots particles like atoms at each other at extraordinary speeds which forms new elements |
