AST101H1 Lecture Notes - Lecture 10: Atomic Number, Photon, Mass Number

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler, C. Barth Netterfield, Ilana MacDonald

Document Summary

All matter is made of atoms, which all have. Nucleus made of positively charged protons and neutral neurons. Number of protons determines which element the atom is composed of. Number of electrons = number of protons in nucleus. Mass number = number of protons + neutrons. Phases of matter : materials behave different at different temperature. Solid: atoms/molecules are held in rigid structure. Liquid: atoms/molecules are stuck together, but change positions. Plasma: when material very hot, electrons separate from nucleus (interior of sun) Transmitted as photons: think of them as tiny baseballs travelling at light speed. Each photon of a given colour (wavelength/frequency) carries exactly same energy. Red light: low frequency, carried by low-energy photons. Blue light: high frequency, carried by high-energy photons. Electron can change to higher energy orbital by absorbing photon of light corresponding exactly to energy change. Absorption line: light missing at one specific colour. Earth"s atmosphere blocks out specific colours from sunlight.