BIOL 150 Chapter Notes - Chapter 2: Louis Pasteur, Electron Shell, Atomic Number
Document Summary
Tested the idea that organisms arise from nonliving organisms. Maintains that inputs of energy led to the formation of increasingly complex carbon- containing substances, culminating in a molecule that could replicate itself. 4 types of atoms: hydrogen, carbon, nitrogen and oxygen. Make up 96% of all matter found in organisms today. *they all can be measured in grams (g). # of protons = # of electrons (balanced and neutral) Mass number (# of protons and neutrons) Dalton (da) (special unit used to measure n, p and e) Mass of p and n virtually identical and are routinely rounded to 1 da each. Mass of electron so small that it"s normally ignored. *if atomic number changes, then it"s no longer same element* Isotopes (form of an element with different numbers of neutrons) (equal-places) *isotopes of same element have different masses because they have different numbers of neutrons* Atomic weight (average of all masses of naturally occurring isotopes based on their abundance)
