Properties of Water Polarity Polarity is when one

Properties of Water

Polarity Ø Polarity is when one atom attracts electrons more strongly than another atom. l In H 2 O, the oxygen atom (O) attracts electrons more than the hydrogen atom (H). Ø The water molecule acts like the oxygen is positively charged and the hydrogen is negatively charged.

Hydrogen Bonds Ø When water molecules are close, weak bonds form between the hydrogen and oxygen atoms.

Hydrogen Bonds (con’t) Ø Cohesion – attraction between molecules of the same substance. l Because water forms hydrogen bonds, water molecules stick together very tightly • This is why water forms drops when placed on a flat surface.

Hydrogen Bonds (con’t) Ø Adhesion – attraction between molecules of different substances. l l Water can form hydrogen bonds with other materials. This is why water can rise up in narrow tubes.

Aqueous Mixtures Ø Water l l can form two kinds of mixtures. Solutions Suspensions

Solutions Ø All components of a solution are mixed evenly. l l Solute – the substance that is dissolved. Solvent – the substance that the solute dissolves in.

Suspensions Ø Small particles of material do not dissolve in water, but do not settle out. l Example: Coffee, Tea, Blood

p. H scale Ø Measure the amount of H+ ions in a solution. Ø Ranges between 0 -14. Ø For each increase in unit, the amount of H+ ions increases by 10. l l From p. H 2 to p. H 3, the p. H increases by 10 From p. H 2 to p. H 4, the p. H increases by 100

Acids Ø An acid is any substance that will form H+ ions in water. Ø Acids have a p. H range of less than 7

Bases Ø Bases are any substance that forms OHions in solution. Ø Bases have a p. H range over 7.

Class work Ø Pg l 57 1 -5, 11 -13, 15 -17