Warm Up Riddle

1. You are shown five cards face down on a table. You are told that the five cards are as follows: 1 Joker and 4 Aces (each of a different suit). Given the following information, determine the position for each card. Warm Up Riddle

2. The club is to the immediate right of the heart. Neither the diamond nor the joker is next to the spade. Neither the joker nor the diamond is next to the club. Neither the diamond nor the spade is next to the heart. Warm Up RIDDLE

3. WARM Up RIDDLE

4. The Periodic Table

5. By the 1850s, chemists had successfully identified 58 elements and they were not sure how many more remained to be discovered. Using chemical symbols (like H for Hydrogen), chemists were able to communicate about the elements and they were often grouped together in families. Unfortunately, the elements within these families often behaved very differently from each other and it became clear that a better system was needed. The Need For Better Classification

6. Dmitri Mendeleev • Born in 1834 in a village outside of Tobolsk, Siberia. • He was instrumental in developing the modern Periodic Table.

7. Dmitri Mendeleev • Mendeleev felt as though elements could be grouped according to their atomic masses and other similar properties. • By arranging the elements in order of increasing atomic mass, Mendeleev found that the properties of the elements repeated at periodic intervals.

8. Dmitri Mendeleev

9. Dmitri Mendeleev • Throughout his research he encountered places where the periodic patterns were broken. He decided to leave these spaces blank. • Mendeleev was even able to use his table to predict the existence of then unknown elements. • His predictions were amazingly accurate.

10. The Modern Periodic Table

11. By about 1915, detailed models of atomic structure had been developed. Amazingly, Mendeleev’s Periodic Table was also able to reflect atomic structure as well as atomic mass and physical and chemical properties. As it turns out, atomic structure is the basis for periodicity in the periodic table and so Mendeleev’s table had to be slightly reorganized. This time, the focus was on atomic structure rather than on atomic mass. The modern periodic table is based on atomic number and this number is unique to each element. The Modern Periodic Table

12. The Modern Periodic Table

13. Groups of Elements • Group 1A - The Alkali Metals • These elements are all very reactive metals.

14. Groups of Elements • Group 2A - The Alkaline Earth Metals • Elements in this group are also reactive metals but less so than the alkali metals.

15. Groups of Elements • Group 7A - Halogens • These elements react vigorously with many things. Even the least reactive halogens are extremely corrosive and harmful.

16. Groups of Elements • Group 8A - Noble Gases • The noble gases are named as such because they are so unreactive. They rarely combine to form compounds and, when they do, they quickly decompose back into single atoms.

17. Is the atom really the smallest form of matter? Atomic Structure

18. In the early 1800s, a British schoolteacher named John Dalton suggested a new way to distinguish between different elements and compounds. He began experimenting with different gases and liquids to study their chemical changes. From his experimental results, he developed what is now known as Dalton’s atomic theory. From Particle Theory to Atomic Theory

19. 1. All matter is made up of small particles called atoms. 2. Atoms cannot be created, destroyed, or divided into smaller particles. 3. All atoms of the same element are identical in mass and size. The atoms of one element are different in mass and size from the atoms of other elements. 4. Compounds are created when atoms of different elements link together in definite proportions. Dalton’s Atomic Theory

20. According to John Dalton, the smallest form of matter was the atom. • An atom was, by definition, meant to be indivisible. • The word atom comes from the Greek word for indivisible or uncuttable. • Towards the end of the 19th century, this belief started to change. Atomic Structure

21. What Happened? • First, scientists like Heinrich Geissler developed technology that allowed electricity to flow through tubes with very little air. • These tubes came to be known as Cathode Ray Tubes.

22. Discovering the Electron • When using Cathode Ray Tubes (with different metal cathodes), scientists began to notice that the positive end (anode) glowed when pressure inside the tube was lowered. • As a result, scientists were led to believe that the glow was produced when the glass is struck with some kind of ray coming from the cathode.

23. Discovering the Electron • Eventually scientists learned that the Cathode Rays were, in fact, particles. • J.J. Thomson furthered the research by showing that these particles were negative. • Rather than calling them cathode rays, scientists settled on the name electrons.

24. J.J. Thomson’s Inferences • Thomson knew that atoms had no charge but he also knew that electrons must be a part of atoms. • What was missing? • Thomson proposed that atoms also contain protons. • Thomson’s Inferences: • Atoms contain both protons and electrons. • All protons are the same and all electrons are the same. They are different from each other, however. • Electrons are negative and protons are positive but there charges are equal. • A proton is considerably more massive than an electron.

25. The PLUM PUDDING MODEL • As it turns out, the atom is divisible; it is made up of tiny subatomic particles (protons and electrons). • Thomson thought that the atom would appear something like a raisin bun.

26. X-Rays • While other scientists were busy figuring out the components of the atom, Wilhelm KonradRöntgen accidentally used Cathode Ray Tubes to discover X-rays. • As some of you are probably keenly aware, modern medicine would be very different without X-rays.

27. Radioactivity • As a result of Röntgen’s work, Henri Becquerel decided to see if sunlight gave off X-rays too. • He tested his hypothesis by placing samples of crystals (some containing uranium) on fully wrapped photographic plates and then he placed them in the Sun. • This testing, in the end, didn’t matter. • On a cloudy day, he placed the crystals and the photographic plates in a dark drawer. • Becquerel was obviously surprised when he found that the films were exposed even in complete darkness.

28. RADIOACTIVITY • Clearly, some new self-generated rays were coming from the uranium bearing samples. • Marie Curie took a great interest in this discovery and she coined the term radioactivity to describe the emission of these new rays.

29. Ernest Rutherford • As a result of Madame Curie’s research, the Kiwi scientist Ernest Rutherford performed many experiments and he eventually discovered that radioactivity included three types of radiation: • Alpha particles (a) • Made of matter • 4x the mass of 1 proton • Same positive charge as 2 protons • Beta particles (b) • Made of matter • Same mass as 1 electron • Same negative charge as one electron • Gamma rays (g) • Made of energy • No mass • No charge

30. Using his knowledge of radiation and the particles involved, Rutherford designed an experiment to probe the atom. He used alpha particles as “atomic bullets.” The alpha particles were shot from a polonium source towards a thin strip of gold foil. Rutherford’s Gold Foil Experiment

31. Rutherford’s experiment also led to an unexpected discovery; Gold has 79 protons in its nucleus but their total mass accounts for less than half of the mass of the nucleus. Something was missing… Rutherford correctly inferred that the nucleus must contain additional, uncharged particles. These particles came to be known as neutrons. What about the Missing Mass?

32. The BOHR-Rutherford MODEL • As we already know, opposites attract. Therefore, why weren’t the electrons crashing into the positive nucleus? • Niels Bohr reasoned that electrons don’t crash into the nucleus because they revolve at just the right speeds to remain in distinct orbits around the nucleus.

33. The Bohr-Rutherford Model • These electron orbits came to be known as electron shells. • Bohr concluded that given electrons are in particular shells based on how much energy they possessed.

34. BOHR Model of a Nitrogen Atom

35. OTHER BOHR DIAGRAMS

36. The number of protons in the nucleus of an atom is the atomic number. • The atomic number is what identifies an atom as a specific element. • Ex: If the atomic number of an atom is 6, the element must be carbon. Atomic Number

37. The sum of the number of protons and the number of neutrons in an atom is called the mass number. The mass number is always a whole number. Atomic Mass Number

38. C Chemical Symbols 12 Mass Number Chemical Symbol 6 Atomic Number

39. Atomic Number = Number of protons Mass Number = Number of protons + number of neutrons Number of neutrons = Mass number – number of protons Number of protons = Number of electrons (in a neutral atom) Calculating the Number of Subatomic Particles

40. What happens when you change the number of protons in an atom? • If the number of protons changes, the atomic number changes and you have a different element. • This is not an easy thing to do! Protons, Electrons and Neutrons

41. What happens when you lose or gain neutrons in an atom? Many elements have atoms that exist with varying numbers of neutrons within their nuclei. Isotopes: Forms of an element that have the same number of protons but different numbers of neutrons. ISOTOPES

42. ISOTOPES OF HYDROGEN

43. DEUTERIUM • Deuterium is a major component in Canada’s CANDU Nuclear Reactors. • These reactors use heavy water (water containing deuterium) as a way to transfer heat energy from the radioactive uranium to the steam generators.

44. CARBON-14 Dating • Carbon also has a number of isotopes. • By far the most common isotope is carbon-12. • Carbon-14 is slightly radioactive and it can be used to determine the age of organic (carbon-based) remains.

45. CARBON-14 Dating • Living tissues are constantly ingesting small amounts of carbon-14. • When an organism dies, however, carbon-14 is no longer incorporated into the tissues. • It then starts to undergo radioactive decay.

46. CARBON-14 dating Not this half-life! • Carbon-14 has a half-life of about 5730 years. • Scientists can determine the age of organic remains based on how much carbon-14 is remaining in the tissues.

47. The SHROUD OF TURIN • The shroud is a linen cloth that many believe is the burial cloth placed over the body of Jesus of Nazareth during his burial. • Carbon-14 dating was performed on pieces of the shroud and it was determined that it was likely made in the Middle Ages.

48. The SHROUD OF TURIN

49. We now know what happens when an atom gains or loses protons or neutrons but does anything change when an atom gains or loses electrons? Ions are formed when an atom gains (anion) or loses (cation) electrons. Ions are often used to form compounds. IONS