| A | B |
|---|
| molecule | two or more atoms held together by a chemical bond |
| compound | two or more atoms of different kinds held together by a chemical bond |
| Evaporation | change of liquid state to gas state |
| sublimation | change from solid state to gas state |
| Atom | tiny particle of matter made of protons, electrons, and usually nuetrons |
| troposphere | lowest layer of the atmosphere; where weather occurs |
| stratosphere | contains the ozone layer |
| mesosphere | above the stratosphere |
| thermosphere | heated by high energy light |
| infrared | wavelength of light that we feel as heat |
| ultraviolet | light that causes sunburns and skin cancer |
| ozone | gas that absorbs UV light |
| nitrogen | most abundant gas in atmosphere |
| oxygen | makes up about 21% of the atmosphere |
