BIOL 118 Lecture 1: BIOL118-Lecture1
25 Jan 2017
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Cation- an atom that loses an electron (positively charged) ex) na+ Anion- an atom that gains an electron (negatively charged) ex) cl- The number of unpaired electrons determines the number of bonds an atom can make ex. Carbon has 4 unpaired electrons -- 4 single bonds, 2 double bonds: single bonds, double bonds, triple bond. Substances are more likely to react when dissolved in water. Why is water a great solvent: water is polar. The h-o bonds in water are polar covalent. Oxygen has a high electronegativity: the o = has partial negative charge, the h = has partial positive charge, hydrogen bonds form between water molecules (figure 2. 11b, highly non-polar molecules do not dissolve in water. Hydrophobic- (cid:862)(cid:449)ate(cid:396)-fea(cid:396)i(cid:374)g(cid:863: do not dissolve in water. Hydrogen bonds between h2o and other polar molecules or ions (figure 2. 12: help the substances stay in solution, hydrophilic - (cid:862)(cid:449)ate(cid:396)-lo(cid:448)i(cid:374)g(cid:863) Acids- give up protons in chemical reactions.
