Chapter 4.pdf

4.1
Investigating Matter
Here is a summary of what you
will learn in this section:
• Matter has mass and occupies
volume.
• Matter is composed of
particles. The arrangement and
movement of the particles
determines whether a
substance is solid, liquid, or
gas.
• Matter can be classified as a
pure substance or a mixture.
• Mixtures can be further
classified as mechanical
mixtures, suspensions, and
solutions.
Figure 4.1 Fireworks displays combine art and chemistry.
Figure 4.2 Fireworks are lit with a
flame.
The Chemistry of Fireworks
On Canada Day, when darkness falls, the skies of towns and
cities across the country come alive with colours and sounds.
Flares of red, blue, green, and white are joined by cracks and
bangs as fireworks displays mark Canada’s national day of
celebration (Figure 4.1). Fireworks are an ancient technology,
first invented in China over 2000 years ago. Today, fireworks can
be seen around the world and creating them is an art form called
pyrotechnics. Pyrotechnics is a branch of chemistry, the science
concerned with understanding and changing matter.
The spectacular sights, sounds, and smells of fireworks come
from the fusion of science and art. The designers of fireworks
know that some substances burn with brilliant colours when
heated (Figure 4.2). Aluminum metal is used in the kitchen as
cooking foil. However, when aluminum is heated by an explosion,
the metal burns with a bright white flame. To use aluminum in
fireworks, it is first made into a powder so that it will burn
quickly and spread out easily. The types of fireworks that light up
the night sky or leave a thick glowing trail of light often contain
aluminum.
136 UNIT B Atoms, Elements, and Compounds