Differentiating Elements and Compounds

 

Objective

At the end of the lesson, you should be able to distinguish elements from compounds based on a set of properties.

Elements and compounds are classes under pure substances.

Element

• It is the simplest form of pure substance.
• It is composed of only one kind of atom.
• It could be classified into three: metals, nonmetals, and metalloids.

Compound

• It is composed of two or more elements combined chemically in a fixed proportion by mass.
• It can be classified in terms of properties and elements present.

Compounds: Acids and Bases

Acids

• taste bitter
• turns blue litmus paper to red
• reacts with metals to produce hydrogen gas

Bases

• taste sour
• feel slippery
• turns red litmus paper to red

Examples

Examples of acids are lemon and vinegar.

Examples of bases are soap and drain cleaner.

Compounds: Organic and Inorganic

Organic compounds are compounds containing carbon. However, there are carbon-containing compounds which are considered as inorganic such as carbon monoxide, carbon dioxide, cyanide, carbonate, bicarbonate and carbon disulfide.

Examples

• Elements exist in single atoms.
• Some elements exist in molecules. It consists of more than one atom of the similar type.
• A compound is composed of two or more kinds of atom.

Key Points

• An element is composed only of one kind of atom.
• Elements can be classified into three: metals, nonmetals, and metalloids.
• A compound is composed of two or more elements combined chemically in a fixed proportion by mass.
• Compounds can be classified in terms of properties (acids and bases), and elements present (organic and inorganic).