Grade 9 Unit C: Curriculum Links | Print |

Unit C: Environmental Chemistry
(Social and Environmental Contexts emphasis)

Environments are often viewed from a physical and biological perspective, but to fully understand how they function, it is important to view them from a chemical perspective as well. A study of environmental chemistry helps students become aware that chemical substances make up the underlying fabric of the world and are part of the process in all natural cycles and changes. Through this unit students also become aware of human-produced chemical substances that enter and interact with environments, and investigate potential impacts of different substances on the distribution and abundance of living things.

This unit builds on ideas introduced in Science 8 Unit A: Cells and Systems, Unit B: Mix and Flow of Matter, Unit E: Fresh and Saltwater Systems, and Science 9 Unit B: Matter and Chemical Change. The unit introduces ideas that will be developed further in Science 10 Unit C: Flow ofMatter in Living Systems and in Science 20 Unit B: Changes in Living Systems.

Focussing Questions:

What substances do we find in local and global environments?

What role do they play?

How do changes in their concentration and distribution affect living things?

Key Concepts

  • chemicals essential to life
  • concentration and dispersal
  • substrates and nutrients
  • air and water quality
  • stability and biodegradability
  • organic and inorganic material
  • hazards, probabilities and risk assessment
  • acids and bases
  • uncertainties in environmental monitoring
  • ingestion and absorption of materials
  • uncertainties in assessing toxicity and risk

STS and Knowledge Outcomes

Students will:
Investigate and describe, in general terms, the role of different substances in the environment in supporting or harming humans and other living things

Identify common organic and inorganic substances that are essential to the health and growth of humans and other living things and illustrate the roles served by these materials (e.g., identify calcium as an essential materialfor bones; identify minerals that are known to enhance plant growth-but that limit growth if too little or too much is available).

Describe, in general terms, the forms of organic matter synthesized by plants and animals.

Describe and illustrate processes by which chemicals are introduced to the enviromnent or their concentration is changed (e.g. dilution in streams, biomagnification throughfood chains)

Describe the uptake of materials by living things through ingestion or absorption.

Investigate and describe evidence that some materials are difficult for organisms to break down or eliminate (e.g., DDT mercury)

Identify questions that may need to be addressed in deciding what substances, in what amounts, can be safely released into the environment (e.g., identify questions and considerations that may be important in determining how much phosphate should be released into river water).

Students will:

Identify processes for measuring the quantity of different substances in the environment, and for monitoring air and water quality

Identify substrates and nutrient sources for living things within a variety of environments.

Describe and illustrate the use of biological monitoring as one method for determining enviromnental quality (e.g. assess water quality, by observing the relative abundance of various vertebrate and invertebrate species)

Identify chemical factors in an environment that might affect the health and distribution of living things in that environment (e.g. available oxygen, pH, dissolved nutrients in soil).

Apply and interpret measures of chemical concentration in parts per million, billion or trillion.
[Prerequisite Skills: Grade 8 Matbematics, Number Operations, SO 14, 15]
Identify acids, bases and neutral substances based on measures of their pH (e.g., use indicator solutions or pH meters to measure the pH of water samples)

Investigate safely and describe the effects of acids and bases on each other and on other substances (e.g., investigate and describe the reaction that results when baking powder is dissolved)

Describe the role of acids and bases in neutralizing each other.

Describe effects of acids and bases on living things (e.g., acid rain in lakes, antacids for upset stomachs; pH in shampoos and conditioners)

Students will:

Analyze and evaluate mechanisms affecting the distribution of potentially harmful substances within an environment

Describe mechanisms for transfer of materials through air and water.

Identify factors that may accelerate or retard their distribution (e.g., wind speed, soil porosity).

Describe mechanisms for biodegradation, and interpret information on the biodegradability of different materials.

Comprehend and interpret information on the biological impacts of hazardous chemicals on local and global environments (e.g., interpret evidencefor environmental changes in the vicinity of a substance release, interpret LD50 data)
[LD50 refers to the amount of a substance found to be lethal to 50% of a population, if ingested]
Identify concerns with disposal of domestic wastes such as paints and oils, and industrial wastes.

Describe and evaluate methods used to transport, store and dispose of hazardous household chemicals. (e.g. Swan Hills, Alberta)

Investigate and evaluate potential risks resulting from consumer practices and industrial processes.

Identify processes used in providing information and setting standards to manage these risks (e.g., interpret and explain the significance of manufacturer's information on how wood preservatives can be safely applied, recognize that individuals may have greater sensitivity to particular chemical substances than do others in the general population).

Identify and evaluate information and evidence related to an issue in which environmental chemistry plays a major role (e.g. evaluate evidence that the use of insecticides to control mosquitoes has an effect/has no effect on bird populations)