1. Atoms and Elements Elements and the Planet Earth

2. Air: Elements in the Atmosphere The term atmosphere refers to the gaseous envelope surrounding a planet. There are four elements in our atmosphere. –Nitrogen – 78.03% –Oxygen – 20.99% –Argon – 0.94% –Carbon Dioxide – 0.04%

3. Air Cont. Three of the gases go through cycles that we have studied before. They are: Photosynthesis Respiration Dry air does not contain moisture but most of the air on this planet has some trace amounts of moisture in it therefore there are trace amounts of hydrogen in our atmosphere.

4. Water: Elements in the Hydrosphere Earth is covered mostly in water. The planet is sometimes referred to as the “big blue marble” because of its appearance from space. All of the water on the surface of the planet is referred to as the hydrosphere, a nearly continuous layer of water lying on or just under the surface of the Earth’s crust. Water in its pure sense is H 2 O but most water found is not often pure. It usually contains other dissolved substances.

5. Earth: Elements in the Crust The crust is the outermost layer of solid rock on our planet. Oxygen is the most abundant element in the crust of our atmosphere. –The most common elements in the crust of the earth in order are: Oxygen, silicone, aluminum, iron, calcium, sodium, potassium and magnesium.

6. Earth: Cont. There are very few elements including gold, silver, platinum and copper that exist in nature uncombined with other elements. Most elements react in differing degrees. How strongly an element reacts is known as its reactivity.