Radiation from atoms
Atoms are composed of charged particles
- lightweight electrons (- charge) orbiting around protons (+ charge) and neutrons (no charge).
- Charge of nucleus = # of protons = “atomic number”
- examples: 1 (H), 2 (He), 6 (C), 26 (Fe), up to 92 (U)
- atoms neutral so # electrons = # protons
- electrons in cloud orbiting nucleus
- unlike charges attract
- fuzzy ball of diameter ~ 10-10 m
- this is the size of an atom
- the nucleus is 105 times smaller
- “atomic weight” = # protons + # neutrons
- 1 (H), 4 (He), 12 (C), 56 (Fe), 238 (U)
- mass of H atom 10-24 gm -- very small, even for a U atom
- our gas tube had millions of billions of identical atoms
- each atom radiated the same spectrum