Unit oneChemistry 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

Orbitals

Electron-distributiondiagram

(a)

(b) Separate electronorbitals

Neon, with two filled shells (10 electrons)

First shell Second shell

1s orbital 2s orbital Three 2p orbitals

(c) Superimposed electronorbitals

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. 2-18

(a) Structures of endorphin and morphine

(b) Binding to endorphin receptors

Naturalendorphin

Endorphinreceptors

Morphine

Brain cell

Morphine

Natural endorphin

KeyCarbonHydrogen

NitrogenSulfurOxygen

Chemical reactions Formation or breaking of chemical

bonds to form new substances Reactants Products

Chemical reaction CO2 + H2O ⇢ C6H12O6 + O2

Chemical reactions Temperature Concentration of reactants Catalysts 3H2 + N2 ⇢ 2NH3