1. Common Elements

2. Hydrogen (H) The simplest element The most abundant element in the universe. Found mostly in stars. One of the elements in water (H 2 O) A major part of all living things.

3. Helium (He) Second most abundant element in the universe. Used in balloons, airships, and many scientific applications. First observed in the Sun and later discovered on Earth

4. Carbon (C) All living things are carbon based A major part of fossil fuels Combines with iron (Fe) to form steel

5. Nitrogen (N) Most abundant gas in the atmosphere (78%) Important part of all living things

6. Oxygen (O) Second most abundant gas in the atmosphere (21%). Major part of living things One of the elements in water (H 2 O) Makes up the majority of the Earth’s crust.

7. Sodium (Na) C ombines with chlorine (Cl) to form salt (NaCl) Important part of animal diets. Pure sodium reacts violently with water.

8. Silicon (Si) Most common metalloid 2 nd most abundant element in the Earth’s crust Used in glass, ceramics, cement, and semiconductors Also part of silicone rubbers and plastics

9. Phosphorus (P) Required by all living things. An important fertilizer. White phosphorus will burst into flames when exposed to air and glow in the dark. Red phosphorus is used to make matches

10. Sulfur (S) Also known as “brimstone” Important for all forms of life. Causes onions, garlic, and skunk spray to have strong odors

11. Chlorine (Cl) Combines with sodium (Na) to make salt (NaCl) Chlorine is very poisonous to all forms of life, but small amounts are used keep drinking water safe Chlorine is often used as a disinfectant.

12. Calcium (Ca) The hard parts of animals (bones, teeth, shells, etc) usually contain lots of calcium. Common in the Earth’s crust. Found in limestone

13. Iron (Fe) Most abundant element in the Earth’s interior Most used metal Combines with carbon (C) to make steel. Combines with oxygen (O) in the air to form rust