1. Matter and Its Organization

Question 1

What is the difference between an element and a compound?

Answer 1

• Element: Made of one type of atom.
• Compound: Made of two or more elements chemically combined.

Compounds can only be separated into elements through chemical reactions, whereas elements are indivisible by chemical means.

Question 2

Name the two types of mixtures.

Answer 2

• Homogeneous: Uniform composition (e.g., saltwater).
• Heterogeneous: Non-uniform composition (e.g., sand in water).

Question 3

List the states of matter.

Answer 3

• Solid
• Liquid
• Gas
• Plasma

Question 4

What are molecules?

Answer 4

Groups of two or more atoms bonded together.

Molecules can consist of the same element (e.g., O₂) or different elements (e.g., H₂O).

Question 5

How do physical and chemical changes differ?

Answer 5

• Physical: No new substance formed (e.g., melting ice).
• Chemical: New substance formed (e.g., burning wood).