Covalent bonds

• Methane has four covalent bonds between carbon (C) and hydrogen (H).

• The figure above shows the methane molecule in four different views.

• Notice how these different views represent the atoms and their bonds differently

Dissolving ions in water

• The ability of ions and other molecules to dissolve in water is due to polarity.

• The opposite partial charge of the water molecule surrounds each ion.

NaCl crystal structureNaCl ions in water

The polarity of water

• Water is a polar molecule, meaning that there is an uneven distribution of electron density.

• Water has a partial negative charge near the oxygen atom and a partial positive charge near the hydrogen atoms.

• An electrostatic attraction between the partial positive and negative charges results in the formation of a hydrogen bond.

Hydrogen bondingbetween water molecules

The Energy of Bonds

Biological Energies