2. Matter Anything that has mass and takes up space. Anything that has mass and takes up space. All matter can be measured All matter can be measured Mass Mass Volume Volume Density Density

3. Hundreds of years ago, scientists found that certain types of matter couldn’t be broken down into any other simpler substances Hundreds of years ago, scientists found that certain types of matter couldn’t be broken down into any other simpler substances They called these special pure substances: They called these special pure substances: elements elements

4. No matter how small you divide it, gold is only made of gold atoms.

5. So what is an atom? The smallest particle an element can be divided into and still maintain the properties of that element. The smallest particle an element can be divided into and still maintain the properties of that element. Atoms are the building blocks of all matter. Atoms are the building blocks of all matter.

6. Why learn about atoms? All matter is made of atoms, atoms are the basic building block of everything in the universe

7. What does an atom look like? The model of the structure of the atom has changed as technology has improved and as more evidence has been gathered. The model of the structure of the atom has changed as technology has improved and as more evidence has been gathered.

8. HISTORY OF THE ATOM 460 BC Democritus develops the idea of atoms He pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he called ATOMA (greek for indivisible)

9. First atomic models – roughly based on earth, air, water, and fire

10. HISTORY OF THE ATOM 1808 John Dalton Suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them ATOM S

11. The new model of an atom- a tiny solid sphere

12. HISTORY OF THE ATOM 1898 Joseph John Thompson found that atoms could sometimes eject a far smaller negative particle which he called an ELECTRON

13. Thompson develops the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron's charge 1904 like plums surrounded by pudding. PLUM PUDDING MODEL

14. The new model of an atom- atoms contain smaller, negatively charged particles

15. 1910 Ernest Rutherford English scientist who tested JJ Thompson’s model Rutherford’s new evidence allowed him to propose a more detailed model with a central nucleus. He suggested that the positive charge was all in a central nucleus. This held the electrons in place by electrical attraction

16. Rutherford’s experiment The results? His hypothesis:

17. The new atomic model- a dense, positively charged nucleus in the center surrounded by electrons

18. 1913 Niels Bohr studied under Rutherford in Manchester, England Bohr refined Rutherford's idea by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons.

19. Bohr’s Atom electrons in orbits nucleus

20. The new atomic model- electrons are in orbits around the nucleus at different energy levels

21. 1920’s Electron Cloud Model Electron Cloud Model Electrons surround the positively charged nucleus, but not in set orbits Electrons surround the positively charged nucleus, but not in set orbits They are in different levels, or clouds They are in different levels, or clouds There are set amounts of electrons found in each cloud There are set amounts of electrons found in each cloud

22. The new atomic model- set numbers of electrons are found in different cloud layers

25. Atomic Model History http://www.youtube.com/watch?v=QbWK F9uDF7w http://www.youtube.com/watch?v=QbWK F9uDF7w http://www.youtube.com/watch?v=QbWK F9uDF7w http://www.youtube.com/watch?v=QbWK F9uDF7w https://www.youtube.com/watch?v=thnDx FdkzZs https://www.youtube.com/watch?v=thnDx FdkzZs https://www.youtube.com/watch?v=thnDx FdkzZs https://www.youtube.com/watch?v=thnDx FdkzZs

26. Neutron The neutron was not discovered until 1932 when James Chadwick The neutron was not discovered until 1932 when James Chadwick This new idea dramatically changed the picture of the atom This new idea dramatically changed the picture of the atom

27. ATOMS AND ATOMIC STRUCTURE Atom Nucleus Proton Neutron Electron

28. WHAT IS AN ATOM? o The smallest unit of an element. o Consists of a central nucleus surrounded by one or more electrons.

29. WHAT IS THE NUCLEUS? o The central part of an atom. o Composed of protons and neutrons. o Contains most of an atom's mass.

30. WHAT IS A PROTON? o Positively charged particle. o Found within an atomic nucleus.

31. WHAT IS A NEUTRON? o Uncharged particle. o Found within an atomic nucleus.

32. WHAT IS AN ELECTRON? o Negatively charged particle. o Located in shells that surround an atom's nucleus.

33. Summary Particle Charge Mass (amu) Location Proton positive 1 nucleus Neutron neutral 1 nucleus Electron negative < 1 shells outside the nucleus

34. Atoms are neutral Since protons (positive charge) are equal to the numbers of electrons (negative charge), the overall charge of an atom is neutral Since protons (positive charge) are equal to the numbers of electrons (negative charge), the overall charge of an atom is neutral

35. Atomic number equals the number of ____________ or ___________. Atomic mass equals the number of ______________ + ____________. (mass number) Atoms as Pictured on the Periodic Table Atomic Number Symbol Name Atomic Mass protons electrons protons neutrons

36. Ion charged particle formed when an atom gains or loses an electron

37. Video of particles http://www.youtube.com/watch?v=lP57gE WcisY http://www.youtube.com/watch?v=lP57gE WcisY Bill Nye http://www.youtube.com/watch?v=aNK1 mQfNeik http://www.youtube.com/watch?v=aNK1 mQfNeik

38. Let’s review The Atomic Number of an atom = number of ______________ in the nucleus. (Equal to The Atomic Number of an atom = number of ______________ in the nucleus. (Equal to electrons) The Atomic Mass of an atom = number of _________ _________ in the nucleus. The Atomic Mass of an atom = number of _________ _________ in the nucleus. The number of Protons = Number of ____________. _____________ orbit the nucleus. _____________ orbit the nucleus. Protons Protons + neutrons electrons Electrons

40. Build an atom http://phet.colorado.edu/en/simulation/bui ld-an-atom http://phet.colorado.edu/en/simulation/bui ld-an-atom http://phet.colorado.edu/en/simulation/bui ld-an-atom http://phet.colorado.edu/en/simulation/bui ld-an-atom

41. Atom arrangement animation http://web.visionlearning.com/custom/che mistry/animations/CHE1.3-an- animations.shtml http://web.visionlearning.com/custom/che mistry/animations/CHE1.3-an- animations.shtml http://web.visionlearning.com/custom/che mistry/animations/CHE1.3-an- animations.shtml http://web.visionlearning.com/custom/che mistry/animations/CHE1.3-an- animations.shtml

42. http://www.bbc.co.uk/newsround/223694 68 http://www.bbc.co.uk/newsround/223694 68 http://www.bbc.co.uk/newsround/223694 68 http://www.bbc.co.uk/newsround/223694 68