Understanding Elements and Atoms

What is an element?

• A substance that can be broken down by chemical means

• A substance that cannot be broken down by chemical means

• A compound of two or more substances

• A mixture of different substances

Which of the following is a correct symbol for an element?

• Na for Sodium

• H for Helium

• C for Calcium

• O for Osmium

What makes each element unique?

• The way it reacts with water

• The specific combination of protons, neutrons, and electrons

• The type of chemical bonds it forms

• The number of atoms it contains

How many hydrogen atoms are in a water molecule?

• Three

• Two

• Four

• One

What is the chemical formula for water?

• H2O

• OH2

• HO2

• H2O2