Chemistry

Question 1

What is an element?

Answer 1

An element is a pure substance made up of only one type of atom that cannot be broken down into simpler substances.

Question 2

What are three key characteristics of elements?

Answer 2

1. Cannot be broken down into simpler substances
2. Have unique properties
3. Represented by chemical symbols (e.g., H for Hydrogen)

Question 3

What is a compound

Answer 3

A compound is a substance made up of two or more different elements chemically combined.

Question 4

What do chemical formulas show?

Answer 4

Chemical formulas show the types and numbers of atoms in a compound, with subscript numbers indicating the number of atoms of each element.

Question 5

What’s the difference between physical and chemical changes?

Answer 5

Physical changes are reversible and no new substance is formed (e.g., ice melting), while chemical changes form new substances and are often irreversible (e.g., rusting).