Lecture 11. C. Temp. is Motion. Example: H2O
We'll always use the Kelvin temperature scale: all motion ceases at 0 K = "absolute zero"
Higher temperature means larger motions occur, giving different states (or
phases) of matter. As T increases:
- SOLID: above 0 K, atoms in molecules of ice vibrate -- until vibrations destroy crystalline
structure at 273 K (0o C), and ice melts into water
- LIQUID: above 273 K, molecules flow around each other but are still held together by the tiny
electrical forces of their constituent atoms -- until motions allow some molecules to break free at
373 K (100o C), and liquid boils into steam
- GAS: now molecules are free to fly about, bouncing off of each other -- until collisions
are so violent that the molecules destroy each other (about 1000 K), leaving free H & O atoms, but still a GAS
- PLASMA: finally, H & O atoms hit each other with such force that they knock electrons free,
or IONIZE the atoms, greater than 5,000 K (Sun's surface) -- a gas of e-'s and p+'s and O nuclei (w/ some
e-'s left)
These statements are statistical: they apply to most, but not all, particles
at a given temperature.