Science in Action 9: Matter & Chemical Change Summary | Print |

Unit 2 - Matter and Chemical Change
Summary

Key Concepts

Section Summaries

1.0

? Workplace Hazardous
Materials Information
System (WHMIS) and safety
? substances and their
properties
? elements, compounds, and
atomic theory

1.0

Matter can be described and organized by its physical and chemical properties.
? Recognition of WHMIS symbols is important to lab safety.
? Matter can be organized in different ways. One way is as solids, liquids, and gases. Another way
is as mixtures and solutions.
? Physical properties of matter such as colour, hardness, boiling point, and density are used to
identify substances. Chemical properties describe how a substance interacts with other
substances.

2.0

? substances and their
properties
? elements, compounds, and
atomic theory
? periodic table

2.0

An understanding of the nature of matter has developed through observations
over time.

? Human understanding of matter grew as people suggested explanations for their observations of
the natural world. Theories were confirmed or rejected as people learned more about matter.
? The Greek philosopher Democritus stated that matter was made up of tiny indivisible particles
called atomos. This theory was not widely accepted for 2000 years.
? Investigations by scientists, such as Robert Boyle, in the 1600s confirmed that matter is made up
of tiny particles. Further investigation by researchers gradually developed the understanding we
have today that matter is made up of atoms. Each atom has a nucleus containing protons and
neutrons. Electrons orbit the nucleus.
? Elements are pure substances made up of only one type of atom. The periodic table organizes the
elements according to their atomic number and atomic mass. The atomic number is the number
of protons in the nucleus. The atomic mass is the average mass of an atom of an element.
? Patterns of information on the periodic table include groupings of metals, metalloids, and nonmetals.

3.0

? periodic table
? elements, compounds, and
atomic theory
? chemical nomenclature

3.0

Compounds form according to a set of rules.
? Every chemical compound has a chemical formula and chemical name. The chemical formula
identifies the elements in the compound and their proportions.
? An ion is an atom or a group of atoms that has become electrically charged through the loss or
gain of electrons from one atom to another.
? Ionic compounds form between atoms of metals and non-metals.
? Molecular compounds form between atoms of non-metals.

4.0

? endothermic and exothermic
reactions
? reactants and products
? conservation of mass
? factors affecting reaction
rates

4.0

Substances undergo a chemical change when they interact to produce different
substances.

? A physical change may change the appearance or state of a substance but not its composition
(e.g., melting). A chemical change results in the formation of one or more different substances.
? Reactions involving oxygen are some of the most common types of chemical reactions. These
include combustion, corrosion, and cellular respiration.
? A chemical reaction occurs when substances called reactants interact to produce different
substances called products.
? According to the principle of the conservation of mass, the mass of the products in a chemical
reaction equals the mass of the reactants.
? An exothermic reaction gives off energy. An endothermic reaction takes in energy.
? The rate of reaction can be affected by the addition of a catalyst, or an increase in the
concentration, temperature, or surface area of the reactants.