5.1 Introduction to Carbon Compounds
Carbon compounds are divided into organic and inorganic compounds. Carbon is continually recycled through the environment, living organisms and non-living substances via the carbon cycle.
Learning Objectives
- Define carbon compounds and classify them into organic and inorganic carbon compounds based on their origins.
- Give examples of organic carbon compounds and inorganic carbon compounds.
- Describe the carbon cycle and identify the processes involved in releasing and absorbing carbon dioxide.
- Explain the importance of photosynthesis in maintaining carbon balance in the atmosphere.
The Carbon Cycle and Classification of Carbon Compounds
Carbon compounds are grouped by their origins, and carbon moves between the atmosphere, living things and non-living substances.
Short Explanation
Definition
Carbon compounds are compounds that contain the element carbon, C.
In nature, carbon compounds are divided into two main groups based on their origins.
Organic Carbon Compounds
These originate from living things. Examples include petroleum, silk and charcoal.
Inorganic Carbon Compounds
These originate from non-living things. Examples include limestone and carbon dioxide.
The Carbon Cycle
The carbon cycle shows how carbon elements are recycled through the formation or decomposition of carbon compounds in living things and organic substances in the environment.
Three processes release carbon dioxide into the atmosphere: respiration, combustion and decomposition. One main process absorbs it: photosynthesis by green plants.
Processes in the Carbon Cycle
Carbon dioxide moves into and out of the atmosphere through four main processes.
| Process | What happens | Effect on atmospheric carbon dioxide |
|---|---|---|
| Respiration | Carried out by all living things, including plants, animals and microorganisms. | Releases carbon dioxide |
| Combustion | Burning of fossil fuels such as petroleum, natural gas and coal, as well as natural occurrences like volcanic eruptions and forest fires. | Releases carbon dioxide |
| Decomposition | Decomposers such as bacteria and fungi break down dead organisms. | Releases carbon dioxide |
| Photosynthesis | Green plants absorb carbon dioxide using light energy and chlorophyll to produce glucose and oxygen. | Absorbs carbon dioxide |
Photosynthesis
Green plants absorb carbon dioxide from the atmosphere to carry out photosynthesis.
Inputs
Carbon dioxide is absorbed from the air, water is absorbed by the roots, and light energy comes from the sun. The process happens in chlorophyll.
Products
Glucose and oxygen are produced. Photosynthesis enables green plants to make their own food and provides food to animals.
Importance of photosynthesis. It increases the oxygen content in the air and removes excess carbon dioxide from the air to maintain the carbon dioxide content in the air.
Try to Answer First
Answer in your mind, then press “Check Answer”.
What are the two main groups of carbon compounds based on their origins?
State three processes that release carbon dioxide into the atmosphere.
What is the main process that absorbs carbon dioxide from the atmosphere?
Common Mistakes
- Assuming that any compound containing carbon is automatically an organic compound. Carbon compounds include both organic compounds like petroleum and inorganic compounds like carbon dioxide and limestone.
- Thinking that plants only absorb carbon dioxide and do not release it. Green plants carry out both photosynthesis to absorb carbon dioxide and respiration to release carbon dioxide.
- Forgetting that decomposition releases carbon dioxide into the atmosphere. Decomposers such as bacteria and fungi break down dead organisms and release carbon dioxide through their respiration.
Concept Misunderstandings
Petroleum and coal are inorganic because they are found underground in rocks.
Petroleum and coal are organic carbon compounds because they originate from the remains of ancient living organisms.
Respiration only occurs in animals.
Respiration is carried out by all living things, including animals, green plants and microorganisms.
Summary
- Carbon compounds contain carbon and are classified into organic carbon compounds, from living things such as petroleum, silk and charcoal, and inorganic carbon compounds, from non-living things such as limestone and carbon dioxide.
- Carbon dioxide is released into the atmosphere by respiration, combustion and decomposition.
- Carbon dioxide is absorbed from the atmosphere by green plants during photosynthesis.
- Photosynthesis maintains atmospheric balance by removing excess carbon dioxide, releasing oxygen and producing food for living organisms.
Short Activity
A. Objective Quiz
1 Which of the following is an inorganic carbon compound?
2 What process removes carbon dioxide from the atmosphere to maintain its balance?
B. Fill in the Blanks
3 Carbon compounds that originate from living things are called carbon compounds.
4 Decomposers such as bacteria and fungi release carbon dioxide into the atmosphere during the process of .
C. Drag and Drop: Match Each Process or Substance to Its Description
Drag each item to the correct description. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.
C. Match Each Process or Substance to Its Description
Write the correct item next to each description.
| Description | Item |
|---|---|
| 1. Absorbs carbon dioxide from the atmosphere using light energy | |
| 2. Releases carbon dioxide through living things including plants and animals | |
| 3. Burning of fossil fuels or forest fires releasing carbon dioxide | |
| 4. An inorganic carbon compound originating from non-living things |
Answer choices: Photosynthesis • Respiration • Combustion • Limestone
