Unit one Chemistry of Life Chapter 2

Matter Anything that has mass and occupies space Composed of elements 93.6% of the human body’s weight Carbon Hydrogen Oxygen Nitrogen

Other elements essential to life Potassium Sodium Phosphorus Calcium Sulfur Chlorine Magnesium

Trace elements Iodine Copper Iron Tin Zinc

Atomic structure Atom Atomic number Mass number Isotopes

Radioactive isotope Unstable Nucleus decays Emits particles and/or energy

Electrons Valence electrons Ions Cation Anion Orbitals

Electron-distribution diagram (a) (b) Separate electron orbitals Neon, with two filled shells (10 electrons) First shellSecond shell 1s orbital2s orbitalThree 2p orbitals (c) Superimposed electron orbitals 1s, 2s, and 2p orbitals x y z

Bonds Electronegativity Ionic Covalent Single, double triple Polar vs nonpolar Metallic

Molecular attractions Hydrogen bonds Van der waals Molecule ion Dipole-dipole

Molecular shape Recognition Response Receptors

Fig (a) Structures of endorphin and morphine (b) Binding to endorphin receptors Natural endorphin Endorphin receptors Morphine Brain cell Morphine Natural endorphin Key Carbon Hydrogen Nitrogen Sulfur Oxygen

Chemical reactions Formation or breaking of chemical bonds to form new substances Reactants Products

Chemical reaction CO 2 + H 2 O ⇢ C 6 H 12 O 6 + O 2

Chemical reactions Temperature Concentration of reactants Catalysts 3H 2 + N 2 ⇢ 2NH 3