Chemistry module 4
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16 terms
Terms | Definitions |
|---|---|
 Pure substance | A substance that contains only one element or compound |
| Mixture | A substance that contains different compounds and/or elements |
| Homogeneous mixture | A mixture with a composition that is always the same no matter what part of the sample you are observing |
| Heterogeneous mixture | A mixture with a composition that is different depending on what part of the sample you are observing |
| The composition of air | 21% oxygen, 78% nitrogen, 1% other gases |
| chemical change | A change that affects the type of molecules or atoms in a substance |
| physical change | A change in which the atoms or molecules in a substance stay the same |
| melting | the transition from solid to liquid |
| freezing | the transition from liquid to solid |
| boiling | the transition from liquid to gas |
| condensing | the transition from gas to liquid |
| the phases of matter | solid, liquid, gas |
| kinetic theory of matter | Molecules and atoms are in constant motion, and the higher the temperature, the greater their speed |
| chemical reaction | When the molecules within a substance change into different molecules |
| homonuclear diatomics | elements in nature that are not composed of individual atoms |
| elements made of homonuclear diatomic molecules | nitrogen, oxygen, chlorine, fluorine, bromine, iodine, astatine, hydrogen |
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