chapter 2.3

• water is a polar molecule
• polar: a molecule that reigons of positive and negative charge
• hydrophillic: water loving, hydrogen bonded
• hydrophobic: water fearing, not hydrogen bonded
• water dissolves most substances
• solvent: a liquid capable of dissolving substance
• aqueous: watery
• hydrophobic effect: the exclusion of non polar molecules, which drives biological processes such as the formation of cell membranes and folding proteins
• hydrogen bond: an interaction between a hydrogen atom and electronegative atom, depicted by a dashed line
• hydrogen bonds are weaker than covalent bonds
• weak hydrogen bonds can help stabilize biological molecules
• cohesion: attraction between molecules, causes surface tension
• cohesion between molecules contributes to water in plants
• molecules are in constant motion, and the motion increases as the temperature increases
• when water is heated, some energy added by heating is used to break hydrogen bonds
• pH is a measure of the concentration of protons in solution
• pH= -log[H+]
• the pH scale ranges from 0-14, neutral pH is 7
• acidic: when the concentration of protons is higher than hydroxide ions
• basic: when the concentration of protons is lower than hydroxide ions
• basic: when the concentration of protons is lower than that of hydroxide, pH is higher than 7
• acid: a molecule that releases a proton (H+)
• base: a molecule that accepts a proton in an aqueous solution