1. Unit 1 Atomic Structure Objectives: List the three major parts of an atom. State the law of charges. Discuss the law of centripetal force. Discuss the differences between semiconductors and insulators.

2. Unit 1 Atomic Structure History The Greeks were the first to discover electricity 2500 years ago. The Greeks called amber elektron. About 300 years ago Charles DuFay studied the force of repulsion and attraction using a glass rod.

3. Unit 1 Atomic Structure List of charged materials.

4. Unit 1 Atomic Structure Unlike charges attract and like charges repel.

5. Unit 1 Atomic Structure Atoms The atom is the basic building block of the universe. An element is a substance that cannot be chemically divided into a simpler substance. The principal parts of an atom are the electron, neutron, and proton.

6. Unit 1 Atomic Structure Atomic Theory An element is composed of only one type of atom. The atomic number of an element is the same as the number of protons in the nucleus. The Periodic Table of Elements lists all the types of atoms or elements known to mankind. A molecule is the result of the joining of two or more different types of atoms.

7. Unit 1 Atomic Structure Water can exist in three states.

8. Unit 1 Atomic Structure Table of elements.

9. Unit 1 Atomic Structure The three principal parts of an atom are the electron, the neutron, and the proton.

10. Unit 1 Atomic Structure The electron has a negative charge and orbits the nucleus. The proton has a positive charge. The neutron has no charge and combines with the proton to form the nucleus.

11. Unit 1 Atomic Structure Protons have a positive charge. Electrons have a negative charge.

12. Unit 1 Atomic Structure The Law of Charges Opposite charges attract!

13. Unit 1 Atomic Structure The Law of Charges Like charges repel.

14. Unit 1 Atomic Structure Centripetal Force prevents an object from pulling away from its axis point.

15. Unit 1 Atomic Structure Electrons form orbits or shells that surround the nucleus.

16. Unit 1 Atomic Structure Electrons orbit the nucleus in a circular fashion.

17. Unit 1 Atomic Structure Valence electrons are located in the outer orbit of an atom.

18. Unit 1 Atomic Structure A copper atom contains 29 electrons and has one valence electron.

19. Unit 1 Atomic Structure Electron Flow Electricity is the flow of electrons. This happens when a free electron knocks another electron free out of its orbit. The striking electron settles into a new orbit. This process repeated many times creates electrical flow.

20. Unit 1 Atomic Structure An electron of one atom knocks an electron of another atom out of orbit and takes its place.

21. Unit 1 Atomic Structure The energy of the cue ball is transferred to the ball being struck.

22. Unit 1 Atomic Structure The energy of the striking electron is divided.

23. Unit 1 Atomic Structure The energy of the cue ball is divided between the other two balls.

24. Unit 1 Atomic Structure The energy of the striking electron is divided among the eight electrons.

25. Unit 1 Atomic Structure Semiconductors Semiconductors are materials that are neither good conductors nor good insulators. They contain four valence electrons. When heated, their resistance decreases. Two common materials are silicon and germanium.

26. Unit 1 Atomic Structure Semiconductors contain four valence electrons.

27. Unit 1 Atomic Structure Molecules are formed when atoms are joined together.

28. Unit 1 Atomic Structure There are six basic methods for producing electricity: 1. magnetism 2. chemical action 3. pressure 4. heat 5. friction 6. light

29. Unit 1 Atomic Structure There are five basic effects electricity can cause: 1. magnetism 2. chemical reactions 3. pressure 4. heat 5. light

30. Unit 1 Atomic Structure Producing sound with electricity.

31. Unit 1 Atomic Structure Insulators Insulators resist the flow of electricity. They contain seven or eight valence electrons. Examples of insulators are: rubber, plastic, glass, and wood.

32. Unit 1 Atomic Structure Review: 1.The atom is the smallest part of an element. 2.The three basic parts of an atom are the proton, electron, and neutron. 3.Protons have a positive charge, electrons a negative charge, and neutrons no charge.

33. Unit 1 Atomic Structure Review: 4.Valence electrons are located in the outer orbit of an atom. 5.Insulators are materials that do not provide an easy path for electron flow. 6.Insulators are made from materials containing seven or eight valence electrons.

34. Unit 1 Atomic Structure Review: 7.Semiconductors contain four valence electrons. 8.Molecules are formed by joining atoms together. 9.Semiconductors are materials that are neither good conductors nor good insulators.

35. Unit 1 Atomic Structure Review: 10.Six basic methods for producing electricity are magnetism, chemical action, light, heat, pressure, and friction. 11.Five basic effects that can be caused by electricity are magnetism, chemical reactions, light, heat,and pressure.

36. Unit 1 Atomic Structure Review: 12.The law of charges states that like charges repel and opposite charges attract.