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chem 8th grade
| Question | Answer |
|---|---|
| atomic number | the number of protons in the nucleus of an atom |
| electron cloud | a region inside an atom where electrons are like;y to be found |
| Dimitri Mendeleev | created the first periodic table |
| John Dalton | believed "atoms cannot be created or destroyed" #all elements made of atoms which combine to form compounds" |
| therm | unit of heat |
| plastic | term used to describe a material that doesn't return to its original shape after stretching |
| adhesive | able to stick |
| endo | internal within |
| exo | giving out |
| periodic table | table of the elements arranged according to their atomic number |
| family/group | vertical column of elements on the periodic table |
| period | horizontal row of elements on the periodic table |
| chemical property | a property of matter that describes a substance based on its ability to change into a new substance with different properties |
| physical property | a property of matter that can be observed or measured without changing the identity of the matter |
| metals | elements that are shiny,ductile,malleable andare good conductors of thermal energy and electrical current |
| non-metals | elements that are not shiny are poor conductors of thermal energy and electrical current |
| metalloids | elements that have properties of both metals and non-metals: sometimes known as semi-conductors |
| insulators | materials that reduce or inhibit the transfer of thermal energy and electrical current |
| conductors | materials that conduct thermal energy and electric current well |
| ions | a charged particle that forms during chemical changes when one or more valence electrons transfer from one atom to another |