Chemistry Day 10. Monday, September 17 th Tuesday, September 18 th, 2018

Transcription

1 Chemistry Day 10 Monday, September 17 th Tuesday, September 18 th, 2018

2 Do-Now Title: Brainstorm: Unit 1 1. Write down today s FLT 2. Draw what an atom looks like according to Democritus and Dalton 3. Draw what an atom looks like according to J.J. Thomson 4. Draw what an atom looks like according to Ernest Rutherford 5. Use one of the pro-talk sentence frames to tell me something we have learned about atoms or subatomic particles. 6. Underneath your do-now, write Brainstorm list and number 1-20 Finished? Take out your planner and table of contents.

3 Brainstorm Protocol 1. The goal is to generate the longest possible list as a group 2. When prompted to do so, identify who will provide the first answer 3. Then, go clockwise to the next person. 4. Do not skip people and do not say an answer for them. 5. Only say ONE answer at a time 6. Quantity over quality 7. Stay on topic 8. Pencils must be down when I say time is up 9. Lists must be exactly the same

4 FLT I will be able to calculate the mass number and average atomic mass in an atom by completing Atoms CN Standard HS-PS1-8: Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay

5 Notes Protocol Title your notes & add assignment # Complete Cornell-style Copy down all bolded ideas Noise level 0 Raise hand to question/comment Be prepared to pair-share-respond

6 Distinguishing Among Atoms

7 Guiding Questions What makes elements and isotopes different? How can we calculate the number of neutrons in an atom? How can I calculate the atomic mass of an element? Can I explain why chemists use the periodic table?

8 Recall Atoms of the same element are identical Atoms are composed of identical protons, neutrons, and electrons

9 Recall An atom s atomic number (Z) = the # of protons in the nucleus. Defines element.

10 Recall Elements are different because they contain different numbers of protons à if you change the number of protons, you change the element

11 Atoms are electrically neutral Protons have a +1 charge What balances them? Electrons have a -1 charge Therefore, # protons = # electrons in an atom Recall

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13 Groups have similar properties

14 Recall: Protons have a relative mass of 1 Neutrons have a relative mass of 1 Electrons have a relatively insignificant mass Mass Number

15 Therefore Mass # = p + + n 0 Mass Number Nuclide p + n 0 e - Mass # Oxygen

16 Shorthand Notation Mass Number Symbol Atomic Number

17 Shorthand Notation Find each of these: a) number of protons b) number of neutrons c) number of electrons 14 C d) Atomic number e) Mass Number 6

18 Shorthand Notation If an element has an atomic number of 34 and a mass number of 78, what is the: a) number of protons b) number of neutrons c) number of electrons d) shorthand notation

19 Shorthand Notation If an element has 91 protons and 140 neutrons what is the a) Atomic number b) Mass number c) number of electrons d) shorthand notation

20 Shorthand Notation If an element has 78 electrons and 117 neutrons what is the a) Atomic number b) Mass number c) number of protons d) shorthand notation

21 Isotopes What was Dalton mistaken about? Dalton was also wrong about all elements of the same type being identical

22 Isotopes Atoms of the same element can have different numbers of neutrons. Thus, different mass numbers. These are called isotopes.

23 Isotopes Frederick Soddy ( ) proposed the idea of isotopes in 1912 Isotopes = atoms of the same element having different masses, due to varying numbers of neutrons. Soddy won the Nobel Prize in Chemistry in 1921 for his work with isotopes and radioactive materials.

24 Isotopes We can also put the mass number after the name of the element: carbon-12 carbon-14 uranium-235

25 Isotopes Isotope Protons Electrons Neutrons Nucleus Hydrogen 1 (protium) Hydrogen -2 (deuteriu m) Hydrogen -3 (tritium)

26 Isotopes Elements occur in nature as mixtures of isotopes.

27 Atomic Mass How heavy is an atom of oxygen? It depends, because there are different kinds of oxygen atoms. We are more concerned with the average atomic mass. Average atomic mass = weighted average of the isotopes of a given element based on the abundance (%) in nature

28 Atomic Mass Each isotope has its own atomic mass, thus we determine the average from percent abundance.

29 Calculating Atomic Mass Multiply the atomic mass of each isotope by it s abundance (expressed as a decimal), then add the results. If not told otherwise, the mass of the isotope is expressed in atomic mass units (amu)

30 Atomic Masses Atomic mass is the average of all the naturally occurring isotopes of that element. Isotope Symbol Composition of the nucleus Carbon C 6 protons 6 neutrons Carbon C 6 protons 7 neutrons Carbon C 6 protons 8 neutrons Carbon = % in nature 98.89% 1.11% <0.01%

31 1. What is Z? Pair-Share-Respond 2. Can atoms of the same element have different numbers of protons? 3. Discuss all information you can derive from the shorthand notation pictured 4. Explain how isotopes differ from one another. 5. What is meant by the term average atomic mass?

32 Chemistry Day 11 Wednesday, September 19 th Thursday, September 20 th, 2018

33 Do-Now Title: Nuclear Notation Review 1. Answer the do-now questions on your worksheet 2. Do not begin working on the other questions until instructed to do so Finished? Take out your planner and table of contents.

34 FLT I will be able to describe the three main types of nuclear radiation by completing Ch. 19 CN A Standard HS-PS1-8: Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay

35 Ch. 19 Part A: Radiation Title your notes & add assignment # Complete Cornell-style Copy down all bolded ideas Noise level 0 Raise hand to question/comment Be prepared to pair-share-respond

36 Ch. 19 Part A: Radiation

37 Guiding Questions What are the two nuclear forces? What are the three types of radioactive decay? Which is the deadliest type of radioactive decay? How do you protect yourself from Alpha radiation?

38 Review Atomic Models

39 Nucleons and Nuclear Forces

40 Subatomic Particles In 1932, James Chadwick discovered the neutron This was important in improving the protonelectron atomic model New model: The proton-neutron nucleus

41 Proton-Neutron Model

42 Subatomic Particles We now have three subatomic particles: Protons p + Electrons e - Neutrons n 0 Nucleons = subatomic particles located in the nucleus of atoms (p + and n 0 ) Nucleons are composed of smaller particles called quarks

43 Forces There are two main forces at play in our nucleus: Electromagnetic force (proton-proton repulsion) Strong force (nucleons stick together)

44 Forces Not all nuclei are stable Positively-charged protons can repel each other Strong Nuclear Force = binds p + and n 0 together in the nucleus

45 Unstable Nuclei Strong force = holds nuclei together over short distances Larger nuclei can be more unstable

46 Nuclear Stability

47 Nuclear Stability Strong Nuclear Force This force can only act over very short distances It is the strongest attractive force (137 times more than electromagnetic) Over extremely short distances, the strong nuclear force overrides the repulsion of the electromagnetic force Looking at the ratio of protons to neutrons can help us determine the stability of the nucleus

48 The region on a graph which indicates all stable nuclei when the number of neutrons are compared to the number of protons for all stable nuclei Band of Stability

49 Nuclear Stability Larger nuclides tend to be more unstable All nuclides with more than 83 protons (bismuth) are unstable Most nuclides want a 1:1 of neutrons: protons Heavier nuclides need more neutrons

50 Pair-Share-Respond 1. What are nucleons? 2. What force holds nucleons together? 3. What types of nuclei tend to be unstable?

51 Radioactivity

52 Radioactivity How does an unstable nucleus release energy?

53 Context Marie Curie ( ) helped discover new elements (Polonium and Radium), as well as radioactive elements Curie studied materials that gave off rays, which she called radioactivity

54 Radiation Radiation = Rays & particles emitted by a radioactive source

55 Radiation Radioisotopes = unstable isotopes whose nuclei undergo changes to become more stable

56 Radioactivity An unstable nucleus decays into a new nucleus by changing its number of protons spontaneously If the number of protons changes, is it the same element anymore?

57 Radioactivity Radioactive decay = unstable nucleus releases energy/emits radiation

58 Types of Radiation

59 Types of Radiation What are the three main types of nuclear radiation?

60 Main Types of Radiation 1. Alpha (α) Radiation 2. Beta (β) Radiation 3. Gamma (Υ) Radiation

61 Alpha Radiation Alpha radiation = Emits alpha particles (helium) Mass number decreases by 4, atomic number decreases by 2

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63 Ex/ Alpha Radiation

64 Beta Radiation Beta Radiation = Emits a beta particle (electron) Mass number stays the same. Atomic number increases by 1.

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66 Ex/ Beta Radiation

67 Gamma Radiation Gamma radiation = Emits a high-e photon(gamma ray). Tends to accompany other nuclear decay processes

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69 Types of Radiation Alpha particles are the least penetrating. Gamma rays are the most penetrating.

70 Figure 4.2: The penetrating power of radiation John Wiley and Sons Publishers

71 Are there other types of decay? α-particle production Spontaneous fission β-particle production Positron production γ-ray production

72 Positron Production Positron = positively charged anti-electron

73 Pair-Share-Respond 1. What are radioisotopes? 2. What are our three main types of radiation? 3. Which type is the most dangerous? 4. What is emitted in beta decay? 5. What is emitted in alpha decay?

74 CW 1. Underneath your notes, complete the questions from page 601: 19.1 Questions #1, 3-7, 9-10, Finished? Read Ch. 19 Carefully

75 Chemistry Day 12 Friday, September 21 st Monday, September 22 nd, 2018

76 Do-Now Title: Video Notes: Nuclear Processes 1. Write down today s FLT. 2. When can you retake quizzes? 3. What can you trade in your dojo points for? List specific examples with how many points they cost 4. Why do some nuclei undergo decay? 5. Identify the three main types of decay, and list them in order from least penetrating to most penetrating 6. Use a pro-talk sentence frame to make a claim about nuclei, radiation, or decay. 7. Write Video Notes underneath your do-now Finished? Take out your planner and table of contents.

77 Video Notes Let s review some of the concepts we covered, as well as look at some topics we will be covering soon

78 Video Notes 1. What are the four fundamental forces? 2. Distinguish between nuclear fusion and fission. 3. An atomic bomb uses which of these processes? 4. Why is radioactive decay useful to us when studying history? 5. One additional fact

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80 Video Notes 1. What are the four fundamental forces? 2. Distinguish between nuclear fusion and fission. 3. An atomic bomb uses which of these processes? 4. Why is radioactive decay useful to us when studying history? 5. One additional fact

81 Introduction to Half-Life

82 Introduction to Half-Life Unstable nuclei decay Do they all decay at the same rate?

83 Introduction to Half-Life The half-life of a nuclide is the time it takes for ½ of the sample to decay After each half-life, half of the remaining atoms have decayed into a new element We can represent this graphically What would that look like?

84 Introduction to Half-Life

85 Mini-Lab

86 Time 1 million years Class data 2 million years 3 million years 4 million years 5 million years 6 million years 7 million years 8 million years 9 million years 10 million years 11 million years 12 million years