1. Temperature, Energy, and Matter
Chapter 7
Temperature, Energy, and Matter

2. Chapter 7 Section 7.1 The Nature of Atoms
Vocabulary
element
atom
compound
molecule
mixture

3. Objectives
Describe the nature of matter at the atomic level.
Explain how Brownian motion supports the theory that matter is made of tiny, invisible particles.
Distinguish between elements, compounds, and mixtures.

4. Matter is made of tiny particles
430 BC, Greek philosophers Democritus and Leucippus
2,300 years few believed
In 1803, John Dalton revived the idea of atoms, but lacked proof.

5. Brownian Motion Robert Brown, a Scottish botanist
1827 noticed tiny particles moving in a jerky motion.

6. Evidence of Atoms
1905 Albert Einstein Brownian proposed the motion is caused by collisions of visible particles and smaller, invisible particles.

7. Throwing marbles at a tire tube moves the tube smoothly
Throwing marbles at a tire tube moves the tube smoothly. Throwing the same marbles at a foam cup moves the cup in a jerky way, like Brownian motion

8. Elements are the purest form of matter
An element is defined as a pure substance that cannot be broken down into simpler substances by physical or chemical means.

9. Water is made from
the elements hydrogen and oxygen.
If you add energy, you can break water down into hydrogen and oxygen, but you cannot break the hydrogen and oxygen down into simpler substances

10. Atoms are the smallest particles that make up elements
A single atom of gold is the smallest piece of gold you can have.
If you split the atom, it will no longer be gold.

11. Size of an Atom A single atom has a diameter of about 10 meters.
1 meter length has 10 billion atoms
-10

12. Atoms of an element are similar to each other
Carbon atoms are different from
sodium atoms, sodium atoms from oxygen atoms.

13. Compounds two or more
different elements chemically joined
Molecules two or more atoms joined together by chemical bonds.
Mixtures more than one kind of atom, molecule, or compound.

14. EXAMPLES Elements Compounds Mixtures
gold, silver, carbon, oxygen and hydrogen
Compounds
water, carbon dioxide, sodium bicarbonate, carbon monoxide
Mixtures
Soup, salad, pizza, chocolate chip cookies, salt water

15. 7.1 Section Review Page 169
Explain why Brownian motion provides evidence for the existence of atoms and molecules.
Describe the difference between elements, compounds, and mixtures.
Give an example of each: element, compound, and mixture.