Basic Chemistry Department of Biology, WCU

Matter Elements 85% in nature Most common C, O2, H, N2

Elements Composed of atoms Protons, neutrons, electrons physical chemical Protons, neutrons, electrons

Identifying elements Number of particles

Identifying elements Protons: identify Electrons: chemical properties 3 measures Atomic number (2He) Mass number (4He)

Identifying elements 3 measures Isotope - Atomic weight (H+ = 1.008)

Bonding Molecule H + H = H2 Compound = 2H + O = H2O Compound = molecule x 2

Chemical bonding Energy of electrons Electron shells Valence shell 1 = 2 e-s, 2 = 8 e-s, 3 = 18 e-s Valence shell

Chemical bonding 1. Ionic bonds Electron donor (cation) and acceptor (anion)

Chemical bonding 2. Covalent bonds Electron sharing (H+) Single, double and triple bonds

Chemical bonding 2. Covalent bonds double bonds

Covalent bonds Non-polar: equal sharing Polar (H2O is a dipole)

Covalent bonds 3. Hydrogen bonds Weak (water beading)

Elements in biology Most are C, H, N, O Organic Inorganic (water, salt, acids)

Inorganic compounds Water High heat capacity High heat of vaporization (sweating) Solvent dissociation (digestion) hydration Cushioning (cerebral fluid)

Acid-base balance Acid Base Releases H + (HCl = H+ + Cl-, digestion) Takes up H+ (NaOH = Na + + OH- = H2O)

Acid-base balance pH Acidity [H+] High pH (alkaline - proton acceptor) Low pH (acid - proton donor) Scale 0 - 14 Logarithmic

pH scale Acidic pH 1 = [H+] 100 Basic pH 14 = [H+] 10-14

Buffer Release H+ if pH increases, bind H+ if pH decreases e.g. proteins Blood pH 7.35 - 7.45