2. Chapter Nineteen: Solutions  19.1 Water  19.2 Solutions  19.3 Acids, Bases, and pH

3. 19.1 Water  We live on a watery planet.  All life on Earth depends on this combination of hydrogen and oxygen atoms.  What are the properties of water that make it so valuable?

4. 19.1 The shape of a water molecule  When two hydrogen atoms each share one electron with an oxygen atom, a neutral molecule is formed.

5. 19.1 The shape of a water molecule  Because negative charges repel, the electrons pairs around the oxygen atom are located where they are the farthest apart.  This results in a geometric shape called a tetrahedron.

6. 19.1 Water is a polar molecule  A water molecule has a negative end (pole) and a positive end.  A molecule (like water) with a charge separation is called a polar molecule.

8. 19.1 Another polar molecule  Ammonia, NH 3, is another polar molecule. With one lone pair and three bonding pairs of electrons.  This gives the ammonia molecule a pyramid shape.

9. 19.1 Water is a polar molecule  Methane, CH 4, is a nonpolar molecule.  Since there are no lone pairs of electrons, the electrons are shared equally between atoms.

11. 19.1 Hydrogen bonds  A hydrogen bond is a bond between the hydrogen on one molecule to another atom on another molecule.  Hydrogen bonds are relatively weak so they constantly break and re-form.

12. 19.1 Ice and hydrogen bonds  Frozen water (or ice) has an organized structure that resembles a honeycomb because each water molecule can form hydrogen bonds with four other water molecules.

13. 19.1 Properties of water  Water has a high specific heat value because of hydrogen bonds.  In order for water to boil, enough energy must be added to separate the hydrogen bonds.

14. 19.1 Plants and hydrogen bonds  The attraction between water molecules helps water travel from roots to stems and leaves.

15. 19.1 Water as a solvent  Water dissolves sodium chloride (salt) to form a solution of sodium (+) and chlorine (-) ions.

16. 19.1 Water as a solvent  In general, like dissolves like:  water dissolves polar substances  non-polar solvents dissolve non-polar substances