| A | B |
|---|
| Covalent bonds | atoms share electrons |
| hydrogen bonds | a weak bond between two polar molecules |
| molecule | 2 or more atoms bonded together |
| ionic bond | giving or taking electrons between atoms |
| reactants | the starting materials in chemical reaction |
| chemical reaction | making new substances by breaking bonds and forming new bonds |
| products | substances formed from a chemical reaction |
| ions | atoms that have a charge |
| compound | matter made of 2 or more different elements in a chemical reaction |
| valence shell | outside shell of electrons in an atom |
| exothermic energy | energy given off in chemical reaction--gasoline burns in an engine |
| endothermic | energy needed to break a chemical bond |
| conservation of mass | in chemical reaction matter is not created or destroyed--stays the same |
