Sodium loses an electron and chlorine gains an electron. Simply put. It's a little more complicated, but that's what i think they're looking for.
Warmer atoms expand. There is also more movement. This is also explained when putting it into terms with solid vs. gas. In a solid, the atoms vibrate, but they can't move very far because there is not a lot of space between them. In a gas, on the other hand, the atoms are spread apart, and they move very fast. Putting it into context with water, the steam (gas) version is hot, and the ice cube (solid) version is cold. Which one moves more freely? The gas.
A fish species that specializes in eating only a few aquatic plants species
