S8Q3 Atoms, subatomic particles, ions and isotopes

Atomic structures

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2. hivessel _hivessel [email protected] Hivessel.com REVIEW

3. hivessel _hivessel [email protected] Hivessel.com 🧠 What Are Atomic Models?

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8. hivessel _hivessel [email protected] Hivessel.com Atomic models are not guesses. They are based on evidence. As scientists discovered more, they updated their models. Just like upgrading a drawing based on a better photo! 🧠 What Are Atomic Models?

9. hivessel _hivessel [email protected] Hivessel.com Why do you think scientists didn’t just keep one model forever?

10. hivessel _hivessel [email protected] Hivessel.com

11. hivessel _hivessel [email protected] Hivessel.com DEMOCRITUS VS ARISTOTLE

12. DEMOCRITUS Discontinuity of matter _Atom – smallest and indivisible particle of matter 12

13. hivessel _hivessel [email protected] Hivessel.com Democritus: matter made of “atomos,” tiny uncuttable pieces. Aristotle disagreed → people followed him because he was more famous. Problem: No experiments, just ideas.

14. hivessel _hivessel [email protected] Hivessel.com 📚 Types of Atomic Models Through Time 2. John Dalton “Billiard Ball Model”(1803) Source: sutori 🔹 He said atoms are like solid balls —tiny, indestructible, and all atoms of the same element look exactly the same. 📌 Example: Like tiny marbles. Every oxygen atom is one kind of marble, and every hydrogen atom is another kind.

15. JOHN DALTON Atomic theory – explained the laws of chemical change 15

16. DALTON’S ATOMIC THEORY 1. Elements are composed of minute, discrete, and indivisible particles called atoms. 16 2. Atoms of the same element are identical. Atoms of different elements are different.

17. DALTON’S ATOMIC THEORY 17 3. Compounds are composed of atoms of more than one element. In any compound, the combination of atoms is in a fixed ratio of small whole numbers. 4. A chemical reaction involves the separation, combination, or rearrangement atoms. It does not result in the destruction of the atoms nor the creation of other kinds of atoms.

18. hivessel _hivessel [email protected] Hivessel.com PROBLEM/ LIMITATION Didn’t know about smaller particles inside atoms.

19. hivessel _hivessel [email protected] Hivessel.com 📚 Types of Atomic Models Through Time 3. JJ Thomson’s Plum Pudding Model (1897) Source: britannica 🔹 Key Idea: He discovered electrons, tiny negative particles inside the atom. He thought the atom was like a pudding with electrons like raisins mixed in! 🔹 Why It’s Important: It introduced electrons, the first subatomic particle. 📌 It showed that atoms were not solid—there were parts inside them!

20. hivessel _hivessel [email protected] Hivessel.com PROBLEM/ LIMITATION No nucleus, didn’t explain where positive charge came from.

21. hivessel _hivessel [email protected] Hivessel.com 📚 Types of Atomic Models Through Time 3. Ernest’s Rutherford The Nuclear Model (1897) Source: britannica 🔹 Key Idea: He discovered that atoms have a nucleus in the center that is very small and dense, with positive protons. Electrons move around it. Most of the atom is empty space! 🔹 Why It’s Important: Discovered the nucleus and space inside atoms. 📌 His famous “gold foil” experiment helped prove this model!

22. hivessel _hivessel [email protected] Hivessel.com PROBLEM/ LIMITATION Couldn’t explain why electrons don’t fall into the nucleus.

23. hivessel _hivessel [email protected] Hivessel.com 📚 Types of Atomic Models Through Time 4. Bohr’s Planetary Model (1913) Source: Britannica 🔹 Key Idea: Electrons move in fixed paths or energy levels around the nucleus. 🔹 Visual: Like a solar system—sun in the middle, planets (electrons) orbiting. 🔹 Why It’s Important: Explained how electrons are organized in an atom. 📌 It helped scientists understand chemical reactions better.

24. hivessel _hivessel [email protected] Hivessel.com PROBLEM/ LIMITATION Only worked for hydrogen, not bigger atoms.

25. hivessel _hivessel [email protected] Hivessel.com 📚 Types of Atomic Models Through Time 5. Electron Cloud Model (Modern Model) Source: ZMe Science 🔹 Key Idea: Electrons don’t travel in fixed paths but in regions called orbitals or “clouds.” 🔹 Visual: Like a cloud around the nucleus—you can’t tell the exact location, but you know the area. 🔹 Why It’s Important: This is the current and most accurate model. 📌 It’s based on quantum mechanics and used by scientists today!

26. hivessel _hivessel [email protected] Hivessel.com The atomic model has changed many times. Each model had strengths but also problems. Scientists tested, corrected, and improved the models through experiments. Science is always changing when new evidence is found.

27. hivessel _hivessel [email protected] Hivessel.com If scientists discover new particles tomorrow, what do you think will happen to our atomic model?

28. hivessel _hivessel [email protected] Hivessel.com Do you think the first idea about the atom is still correct today? Why or why not?

29. hivessel _hivessel [email protected] Hivessel.com Atomic Model Puzzle Race

30. hivessel _hivessel [email protected] Hivessel.com You will work in groups. Your goal is to arrange the development of the atomic model in the correct order — from the earliest idea to the most recent model. For each scientist, you must state three things: (1) their name, (2) their contribution or model, and (3) the limitation of their model. At the end, your group will present your final timeline to the class.

31. hivessel _hivessel [email protected] Hivessel.com What lesson about science can we learn from the fact that the atomic model changed many times?

32. The Atom: A Look Into the Ultimate Particle 32

33. THE SUBATOMIC PARTICLES 33

34. THE SUBATOMIC PARTICLES 34

35. THE SUBATOMIC PARTICLES 35 The Electron Comes from the Greek word electron meaning “amber” Negatively charged particle Located outside the atomic nucleus

36. THE SUBATOMIC PARTICLES 36

37. THE SUBATOMIC PARTICLES 37

38. THE SUBATOMIC PARTICLES 38

39. EUGEN GOLDSTEIN 39 He worked with a special kind of discharge tube. Instead of just seeing the cathode rays (electrons) , he noticed rays moving in the opposite direction . He called them “Kanalstrahlen” or canal rays (now known as positive rays ). These rays showed that atoms also contained positively charged particles .

40. ERNEST RUTHERFORD Conducted a gold foil experiment which led to the discovery of the atomic nucleus. Nucleus - Occupies a very small portion but is massive and its mass almost constitutes the total mass of the atom. 40

41. THE SUBATOMIC PARTICLES 41

42. THE SUBATOMIC PARTICLES 42 The Neutron An uncharged particle found in an atom’s nucleus Established by James Chadwick

43. THE SUBATOMIC PARTICLES 43

44. THE SUBATOMIC PARTICLES 44

45. Atomic Number and Mass Number 45

46. The atomic number serve as the identity of an atom. The mass number usually corresponds to the atom’s total number of nucleons. 46 Nucleons -Particles in the nucleus (p+ and n)

47. The atomic number serve as the identity of an atom. The mass number usually corresponds to the atom’s total number of nucleons. 47 Nucleons -Particles in the nucleus (p+ and n)

48. Atomic number(Z) = # of protons = # of electrons Mass number (A) = # of protons + # of neutron number of neutrons = A-Z

49. 49 Element Atomic Number Mass Number Number of p+ Number of e- Number of n A 20 40 B 84 48 C 82 125 D 52 76 E 108 47 A. Complete the following table.

50. 50 Element Atomic Number Mass Number Number of p+ Number of e- Number of n A 20 40 20 20 20 B 36 84 36 36 48 C 82 207 82 82 125 D 52 128 52 52 76 E 47 108 47 47 61 A. Complete the following table.

51. 51 Element Atomic Number Mass Number Number of p+ Number of e- Number of n Hydrogen 1.) 2 2.) 3.) 4.) B 5.) 108 6.) 47 7.) C 8.) 9.) 39 10.) 89 D 55 11.) 12.) 13.) 78 14.) 15 15.) 15 15 15 QUiz. 2 Complete the following table.

52. 52 Element Atomic Number Mass Number Number of p⁺ Number of e⁻ Number of n Hydrogen 1 2 1 1 1 B (Silver) 47 108 47 47 61 C (Yttrium) 39 128 39 39 89 D (Cesium) 55 133 55 55 78 (Phosphorus) 15 30 15 15 15 QUiz. 2 Complete the following table.

53. 53 Element Name of Element Complete Designation of Element A B C D E B. Using your periodic table, identify each element described in part A.

54. 54 B. Using your periodic table, identify each element described in part A. Element Name of Element Complete Designation of Element A Calcium B Krypton C Lead D Tellurium E Silver

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56. Isotopes and Atomic Mass 56

57. ISOTOPES ISOTOPES is defined as the variants of chemical elements that posses the same number of protons and electrons, but different number of neutrons. NUCLEON= The total # of protons and neutrons

58. ISOTOPES In most cases, the atoms of a given element do not have the same mass . 58

59. ISOTOPES Isotopes are primarily represented in two ways: Uranium-235 Uranium-239 mass number mass number

60. ISOTOPES Isotopes are primarily represented in two ways: C 12 6 symbol Atomic number Mass number

61. ISOTOPES Atomic number(Z) = # of protons = # of electrons Mass number (A) = # of protons + # of neutron number of neutrons = A-Z

62. ISOTOPES CARBON ISOTOPES ISOTOPE NUMBER OF PROTONS NUMBER OF NEUTRONS Carbon-13 6 7 Carbon- 14 6 8

63. 235 U 92 U 238 92 U 92 234 PRACTICE PROBLEM ISOTOPE NUMBER OF PROTONS NUMBER OF NEUTRONS NUMBER OF ELECTRONS ATOMIC NUMBER MASS NUMBER Uranium-235 92 143 92 92 235 Uranium-238 92 146 92 92 238 Uranium-234 92 142 92 92 234

64. IONS Is an atom or group of atoms that has an electric charge Cation – Ions with a positive charge Anion – Ions with a negative charge 64

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66. EXERCISE ATOMIC NUMBER MASS NUMBER NUMBER OF PROTONS NUMBER OF NEUTRONS NUMBER OF ELECTRONS ISOTOPIC SYMBOL ELEMENT NAME 84 211 (1) (2) (3) (4) (5) (6) 140 (7) 82 (8) (9) (10)

67. EXERCISE ATOMIC NUMBER MASS NUMBER NUMBER OF PROTONS NUMBER OF NEUTRONS NUMBER OF ELECTRONS ISOTOPIC SYMBOL ELEMENT NAME 84 211 84 127 84 Polonium-211 Polonium 58 140 58 82 58 Cerium -140 Cerium