Chapter 1 Activity 4: Are Atoms Divisible?

1. Chapter 1Activity 4: Are Atoms Divisible?

3. (1st Verse) They’re tiny and they’re teeny, Much smaller than a beany, They never can be seeny, The Atoms Family.  (Chorus) (2nd Verse) Together they make gases, And liquids like molasses, And all the solid masses, The Atoms Family  (Chorus) (Chorus) They are so small. (snap, snap) They’re round like a ball. (snap, snap) They make up the air. They’re everywhere. Can’t see them at all. (snap, snap) (3rd Verse) Neutrons can be found, Where protons hang around; Electrons, they surround The Atoms Family.  (Chorus) (4th verse) The periodic table, It isn’t just a fable; You’ll read it when your able; The Atoms Family (Chorus) (Chorus)

5. Democritus Ancient Greece • Greek philosopher • He thought atoms were uncuttable • 3. Therefore: Atoms are indivisible particles • Atomos—Greekmeaning ‘indivisible 470-380 B.C.

6. John Dalton—late 18th century 1. What are atoms? 2. Do Carbon atoms differ from Oxygen atoms? Dalton’s Atomic Model: Hard, indivisible sphere 1766-1834 Yes

8. https://www.youtube.com/watch?v=iVk0yf6MqL4 HAS THIS EVER HAPPENED TO YOU?

9. Are there things inside the atom? YES!Subatomic particles- particles that are smaller than the atome- p+ n0

11. Discovery of electron (e-) Discovered the electron in 1897. J.J. Thomson 1856-1940 • Identified a glowing beam of particles that traveled through a chamber of gas when exposed to an electrical current. Cathode ray tube

12. -This beam (cathode ray) was attracted to positive charges and repelled by negative charges. -Thomson concluded the beam must be composed of negatively charged particles. These came to be known as electrons.

14. Thomson’s Atomic Model “Plum Pudding” Model POSITIVE CHARGE ELECTRONS EMBEDDED WITHIN Negative electron plums are floating around in a sphere of positive pudding.

16. Discovery of the Nucleus 1871-1937 Ernest Rutherford

17. Rutherford’s Au foil Experiment -Discovered the Nucleus (through the Gold Foil Experiment) -Discovered that the atom is mostly empty space -Alpha particle: a positively charged particle, consisting of two protons and two neutrons (helium nucleus). “+” charge Rutherford’s experiment

18. Rutherford’s Nuclear Atom Negative electrons surround nucleus amidst lots of empty space. Positive Nucleus

19. Discovery of the proton Eugen Goldstein In 1886, Goldstein observed rays in a cathode ray tube that traveled oppositely than the electrons previously discovered.

20. James Chadwick 1. Discovered the neutron in 1932 2. This subatomic particle is heavy enough to split a nucleus 3. Led the way to the creation of the atomic bomb

21. Protons Ch 1: Activity 4 • Located in nucleus • Determine which element (DNA) • # of protons = atomic number • equal to # of electrons in a neutral atom

22. LETS HAVE SOME PRACTICE 12 6 Atomic Number (Protons) 6 C Carbon 12 Element Symbol Element Name Mass Number (Proton+Neutrons) Mass Number (Protons+Neutrons) C Atomic Number (Protons)

23. Mass Number Almost all the mass of an atom comes from protons & neutrons # Protons + # Neutrons = mass number

24. Atomic # = # of protons (P) # protons = # electrons in an atom Mass # = number of protons and neutrons (P + N) So,to get the # of neutrons we must Subtract Atomic # from the Mass # = # Neutrons REVIEW TIME C 12 6 6 neutrons

25. Practice Determine the # of protons,neutrons, & electrons

26. Subatomic Particles • Electron: e- • negative charge • 9.11 x 10-31 kg • Proton: p+ • positive charge • 1.67 x 10-27 kg • Neutron: n0 • no charge • 1.67 x 10-27 kg

27. What did Battleship teach us? Battleship simulated Rutherford’s Gold Foil Experiment.

28. Atoms vs Ions

29. IONS Can’t Change the Number of Protons

30. Ions An ion is an atom with a positive (+) or negative (-) charge Atoms that gain electrons have - charges Atoms that lose electrons have + charges

31. Isotopes Atoms of an element can have different numbers of neutrons – these are isotopes The number of protons is always the same, but since more neutrons add more mass, the mass number can be different

32. Isotopes

33. Isotopes

34. Atoms are really small

35. How Big Is An Atom? How Big Is An Atom?

36. The Scale of the Universe http://htwins.net/scale2/ Virtual Atom Ted Talk: How Small is an Atom

37. Practice • The atomic number of an atom is always equal to the total number of: a. Neutrons in the nucleus b. Protons in the nucleus c. Neutrons plus protons in the nucleus d. Protons plus electrons in the atom

38. Practice • If the number of electrons and protons are not equal: a. an atom exists b. an isotope exists c. an ion exists d. None of the above

39. Practice POSITIVE • Once it has lost electrons it is no longer an atom. What is it called? CATION • An atom that has lost electrons has what type of charge?

40. Practice • An atom of 42Ca contains: a. 20 protons and 22 neutrons b. 20 protons and 42 neutrons c. 20 electrons and 42 neutrons d. 20 electrons and 22 protons

41. Practice isotopes • Atoms that have the same atomic number but different mass numbers are called?

42. Practice • Look at the picture below and then fill in the chart:

43. Practice • The nucleus of an Fe-56 atom contains: a. 26 protons, 30 neutrons and 26 electrons b. 26 protons, 26 neutrons and 30 electrons c. 26 protons and 56 neutrons d. 26 protons and 30 neutrons

44. Practice • What did Rutherford’s Gold Foil experiment discover? a. electron b. neutron c. nucleus d. proton

45. Practice • A 52Cr3+ ion contains: a. 24 protons, 52 neutrons, 21 electrons b. 24 protons, 28 neutrons, 24 electrons c. 24 protons, 28 neutrons, 27 electrons d. 24 protons, 28 neutrons, 21 electrons

46. Practice • What is the total number of electrons in an atom with an atomic number of 30 and a mass number of 65? a. 30 b. 65 c. 35 d. 95

47. Practice • Who discovered the electron and how? a. Democritus, atomic theories b. Dalton, cathode ray tube c. Rutherford, gold foil experiment d. Thomson, cathode ray tube