The Foundations of Chemistry

Figure 1-3 Physical changes that
occur among the three states of
matter. Sublimationis the conversion
of a solid directly to a gas without
passing through the liquid state;
the reverse of that process is called
deposition.The changes shown in
blue are endothermic (absorb heat);
those shown in red are exothermic
(release heat). Water is a substance
that is familiar to us in all three
physical states. The molecules are
close together in the solid and the
liquid but far apart in the gas. The
molecules in the solid are relatively
fixed in position, but those in the
liquid and gas can flow around each
other.

8 CHAPTER 1: The Foundations of Chemistry

Figure 1-4 Some physical and chemical properties of water. Physical:(a) It melts at 0°C;

(b) it boils at 100°C (at normal atmospheric pressure); (c) it dissolves a wide range of

substances, including copper(II) sulfate, a blue solid. Chemical:(d) It reacts with sodium

to form hydrogen gas and a solution of sodium hydroxide. The solution contains a little

phenolphthalein, which is pink in the presence of sodium hydroxide.

Gas

Solid Liquid

Melting

Freezing

Condensation

Evaporation

Deposition

Sublimation

(a) (b) (c) (d)