Chemistry of Life

Unit 1 – Ch 2

Elements of Life

• C, O, H, N ….96% of living matter • P, S, Ca, K …. Approx 4 % of living matter• Trace Element : Fe, I (I) is essential to hormone production in the

human thyroid…goiter (Fe) essential for many functions (blood)…cause iron deficiency, fatigue, exhaustion, ADD etc b/c it carries Oxygen

Atoms & Molecules

• Define Matter, Element, Compound• Atom: nucleus, protons,

neutrons, electrons, orbitals• Atomic # - # protons• Mass # - p+ + n0

• Dalton 1.7 x 10-24g …mass of p+ and n0

• Atomic Wt more precise

Isotopes

• Same # of protons but differ is # of neutrons• Radioactive Isotopes- elements w/extra

neutrons….unstable and it splits releasing positrons (positively chgd e-’s) that attract electrons of neighboring atoms (tracers) and generate a gamma ray…shows changing [] and location. PET Scans

Energy Levels of Electrons

• Electrons are the only subatomic structure that are involved in chem rxns

• Potential enery = stored energy e- dist potential energy

Orbitals p37 Fig 2.10

Electron Configurations

Chemical Bonds

Covalent – sharing e-’s

Chemical Bonds

• Polar Covalent bonds – e-’s are not shared equally. 1 atom is more electronegative than the other.

Chemical Bonds

• Nonpolar covalent bonds - share e-’s equally-O2, H2, CH4

Chemical Bonds

• Ionic – transfer electrons from +/- ions

Cation = + chgd ion Anion = - chgd ion

Form Salts

Chemical Bonds

• Hydrogen Bonds – wk bonds amongst electronegative atoms. (H2O and NH3)

Van der Waals

Van der Waals – occur between atoms and molecules that are close to each other.

Shape/Function

• A molecules shape determines its function• Orbitals determine shape

Chem Rxns

• Reactants Products

• Equilibrium when reactants and products have concentrations stabilized