Understanding the Periodic Table: Mendeleev's Legacy and Atomic Structure

1. The Periodic Table Section 2.2

2. Periodic Table

3. The Periodic Table • A Russian scientist, Dimitri Mendeleev, in 1867, organized the known elements into a table according to properties such as: -density -colour -melting point -boiling point

4. Today Mendeleev’s Table is known as the Periodic Table. • http://www.youtube.com/watch?v=JCfxJv83IvA&feature=related • http://www.youtube.com/watch?v=zGM-wSKFBpo&feature=related

5. The periodic Table • Atomic number: the number of protons in the nucleus of the atoms of that element. The number of protons = # of electrons • Note: Atomic numbers increase as you read across each row of the periodic Table.

6. See handout example: Hydrogen

7. Periodic Table • The vertical lines of elements on the table are chemically similar. These vertical lines are called FAMILIES or GROUPS. • There are 18 families on the table.

8. Horizontal lines of elements are called PERIODS . • There are 7 periods in the table.

10. 1. How many protons and elections are in the following atoms. • A) Beryllium (Be) • B) Neon (Ne) • C) Sodium (Na) • D) Carbon ( C ) • E) Sulphur ( S ) • Remember, Atomic Number = # of protons!!!!!

11. 2. The following is a list of atomic numbers for different elements. Identify the elements: • A) 22 • B) 79 • C) 13 • D) 53 • E) 7

12. Complete Activity 2-2A pg. 49 • Remember the following... • #protons (p+) = atomic # • #electrons (e-)= #p+ • #neutrons = atomic mass -#p+

15. MODELS TO REPRESENT ATOMS • Atoms can be represented by electron diagrams which show how many protons and electrons there are in one atom. • They are arranged in “energy levels” or “orbitals”. • An atom can have at most 2 electronsin the first orbital, 8 electronsin the second, 8 electronsin the third orbital and 18 electrons in the fourth orbital.

17. Bohr-Rutherford Model

18. Electrons in Orbitals • In an atom, the first orbital is filled (2 electrons) before the second orbital is filled. • Likewise, the second orbital is filled (8 electrons) before the third orbital. • This trend continues as the third is filled (8 electrons) before the fourth orbital is filled.

19. Figure 2.24

20. Valence Electrons • The electrons in the outer most shell or orbital are called VALENCE ELECTRONS. • This outer shell is called the valence shell. • Elements in the same family (column) have the same # of valence electrons. (Ex. Family 17 are Halogen gases that have seven valence electrons)

21. Atoms react with other atoms to fill their outer electron shell (sharing or “stealing” electrons). • A full valence shell gives an atom stability because it does not have to react to fill its outer valence shell. • Noble gases have full valence shells so they are unreactive for the most part.

22. Valence Electron #= group or family number. • # of energy levels= Period number

23. REACTANT AND PRODUCTS • Another term for chemical change is chemical reaction. In every chemical reaction there is something used up and there is something produced.

25. MASS AND CHEMICAL CHANGE • MASS AND CHEMICAL CHANGE • In a chemical reaction matter changes however the amount of matter does not.

26. The Law of Conservation of Mass states that : • In a chemical reaction, the total mass of the reactants is always equal to the total mass of the products Or • The number of atoms of each element on each side of the arrow must be equal. Or • During a chemical reaction, mass is neither created nor destroyed.

28. TOPIC 7: REACTIONS AS IDENTIFICATION TEST • Chemical Test: a special chemical reaction that allows you to identify an unknown substance.

29. Type 1:To test for oxygen: • oxygen is a clear, colourless gas • it promotes combustion (The chemical reaction in which oxygen in one reactant and heat is produced.

30. Oxygen Test: glowing splint

31. Type 2:To test for hydrogen • clear, colourless gas • it burns explosively • lighter than air • pop test

32. Hydrogen Test

33. Type 3: To test for Carbon dioxide • -clear, colourless gas • -it does not burn • -does not allow other materials to burn • -heavier than oxygen • test review

34. Carbon Dioxide Test

35. Type 4: To test for water • -Clear, colourless liquid

36. Homework • COMPLETE QUESTIONS ON PAGE 39QUESTION 8 AND 10 ON PAGE 57

37. TOPIC 8: ENERGY IN A CHEMICAL REACTION • ENERGY IN A CHEMICAL REACTION • Energy: The ability to do work, to cause motion and to cause things to change

38. Examples of energy: • electrical energy • light or solar energy • gravitational energy • elastic energy • mechanical energy • sound energy • nuclear energy • chemical energy • endothermic vs exothermic

39. Potential Energy Versus Kinetic Energy • Potential Energy (PE) refers to stored energy • Example: Water held back behind a dam contains potential Energy • Kinetic Energy(KE): Energy in motion • Example: Water flowing through the dam causing turbines to turn to produce electricity.

42. Endothermic Reaction: a chemical reaction that absorbs energy • Example: • cooking an egg

43. TOPIC 9: CONTROLLING CHEMICAL REACTION • Reaction Rate - the speed of a chemical reaction

45. Corrosion a type of chemical reaction involving metals which react with other substances in the environment. (H2O, O2) • Eating away of metals • Metal- Elements that are shiny, hard, can corrode, can conduct electricity, and can be pulled into wires or pressed into sheets • Alloy: mixture formed from 2 or more metals • Brass => combination of zinc and copper

46. Internet Resource: • http://www.saskschools.ca/curr_content/science9/chemistry/lesson10.html

47. Questions • 1. List the conditions that favour the formation of rust • 2. Name 4 conditions that would slow down or prevent corrosion • 3. Which would corrode more quickly-steel wool or a steel nail? Why?. • 4. Which might become badly rusted- a bike in Gander or a bike in Harbour Main?

48. TOPIC 10: ACIDS AND BASES