BIOL 1201 Lecture : Lecture 3
Document Summary
Atomic nucleus- contains protons and neutrons, positive charge. Atomic number= # of protons in an element. C-carbon, h-hydrogen, o- oxygen, n-nitrogen, s-sulfur, p-phosphorous, na-sodium, K-potassium, cl- chlorine, ca- calcium, fe- iron, mg- magnesium, cu-copper, b- boron. Radioactive isotopes- nucleus decays, energy and mass are lost. Radioactive isotopes are important tools in experimental studies: trace biochemical pathways, determine rates of synthesis, identify cellular locations. Electronegativity- the tendency of an atom to pull e- towards itself. Orbitals- 3 dimensional space of e- in atom. The first e- shell has one s orbital (1s) The second e- shell has four orbitals (2s, 2p) Unpaired electrons determine atomic reactivity rows= e- shell columns= number of e- Electronegativity scale tendency of an atom to pull towards itself. Covalent bonds- atoms share e- equally (h2) or (o2), the number of unpaired e- in outer most shell (oxygen has 6 meaning it has room for 2 e-, causing a double bond.
