6 Questions
What is the primary characteristic that distinguishes an element from a compound?
The presence of only one type of atom
Which of the following is a characteristic of a mixture?
Variable composition
What is the primary function of a base in a chemical reaction?
To accept hydrogen ions
Which of the following substances is an example of a compound?
Carbon dioxide (CO2)
What is a characteristic of an element that distinguishes it from a compound?
The inability to be broken down into simpler substances
Which of the following is a characteristic of a base?
pH above 7
Study Notes
Substances
Elements
- A substance that consists of only one type of atom
- Cannot be broken down into simpler substances by chemical means
- Examples:
- Hydrogen (H)
- Carbon (C)
- Oxygen (O)
- Properties:
- Have a fixed melting and boiling point
- Have a specific density
- Can exist as solids, liquids, or gases
Compounds
- A substance formed by the chemical combination of two or more different elements
- Have properties different from their constituent elements
- Examples:
- Water (H2O) - composed of hydrogen and oxygen
- Carbon dioxide (CO2) - composed of carbon and oxygen
- Properties:
- Have a fixed ratio of elements
- Can be broken down into simpler substances by chemical means
Mixtures
- A combination of two or more substances, where each substance retains its chemical properties
- Can be separated by physical means, such as filtration or evaporation
- Examples:
- Air - a mixture of nitrogen, oxygen, and other gases
- Soil - a mixture of minerals, organic matter, and other substances
- Properties:
- Variable composition
- Can be separated by physical means
Bases
- A substance that accepts hydrogen ions (H+)
- Can neutralize acids to form salts and water
- Examples:
- Sodium hydroxide (NaOH)
- Calcium hydroxide (Ca(OH)2)
- Properties:
- Have a pH above 7
- Feel slippery to the touch
- Can turn litmus paper blue
Elements
- Consist of only one type of atom
- Cannot be broken down into simpler substances by chemical means
- Examples: Hydrogen (H), Carbon (C), Oxygen (O)
- Have fixed melting and boiling points
- Have a specific density
- Can exist as solids, liquids, or gases
Compounds
- Formed by the chemical combination of two or more different elements
- Have properties different from their constituent elements
- Examples: Water (H2O) - composed of hydrogen and oxygen, Carbon dioxide (CO2) - composed of carbon and oxygen
- Have a fixed ratio of elements
- Can be broken down into simpler substances by chemical means
Mixtures
- A combination of two or more substances, where each substance retains its chemical properties
- Can be separated by physical means, such as filtration or evaporation
- Examples: Air - a mixture of nitrogen, oxygen, and other gases, Soil - a mixture of minerals, organic matter, and other substances
- Have variable composition
- Can be separated by physical means
Bases
- Accept hydrogen ions (H+)
- Can neutralize acids to form salts and water
- Examples: Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH)2)
- Have a pH above 7
- Feel slippery to the touch
- Can turn litmus paper blue
Learn about the basics of elements and compounds, including their definitions, properties, and examples. Test your knowledge of chemistry fundamentals!
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