Elements and Compounds

1. Elements and Compounds

2. Pure substances • Have only one type of particle • Same composition throughout

3. 2 groups: • Elements • Compounds

4. Elements • Cannot be separated by physical or chemical means • 92 elements (naturally occurring) • Classified by properties

5. Unique Characteristic Properties of Elements • Melting point, Boiling point • Density, • Conductivity (heat and electricity) • Reactivity, etc

6. Look @ Fig.3 p83Can you tell the 3 elements apart using… • 1. density?

8. What about … • 2. Conductivity? • 3. Reactivity? • 4. Melting Point?

9. A Substance is identified by • A set of properties • not any one single property

10. Three groups of elements have shared properties: • Metals (most elements) • Nonmetals • Metalloids

11. Metals … • Shiny • Good conductors • Malleable • Ductile • Have high melting & boiling points

12. Examples of metals • Found on the left side of the Periodic Table • Most are solids except for Hg

14. Nonmetals • Dull • Poor conductors • Brittle, unmalleable, not ductile • Lower Melting and Boiling points, Densities.

16. Metalloids • Only 7 of them • Show properties of both metals and nonmetals: • some shiny, some dull; • somewhat malleable, ductile, etc. • Semi-conductors

17. The Metalloids • Boron • Germanium • Silicon • Arsenic • Antimony • Tellerium • Polonium

19. QuizIdentify group(s) of elements that have following properties:metals, nonmetals or metalloids • Good conductors of electricity • Brittle and unmalleable

20. Shiny • Poor conductors of thermal energy

21. Compare Metals and Non Metals

22. Review • Do Review • What is a pure substance?

23. Assignment: • Use a Periodic Table pR12-13 to fill in this table in your notebook: Fill in the first 20 elements then add the ff 15 more …

24. Iron, Cobalt, Nickel, Copper, Zinc, Silver, Tin, Gold, Lead, Mercury, Iodine, Bromine, Lanthanum, Actinium, Uranuim

25. Symbols derived from Latin names of elements

26. Mini-project • Create Flashcards of each element • Get a ring or Ziploc bag or Make a booklet • http://periodictable.com/ Element Chemical symbol Atomic Number State at R.T. Metal/Nonmetal/Metalloid?

27. Section 4-2Compounds The 2nd type of pure substance

28. Two or more elements chemically combined • Atoms combine in specific ratios • They CAN be broken down by chemical means • (Water into hydrogen and oxygen)

29. Compounds to know • (out of nearly 4 million kinds) • Table salt, water, carbon dioxide, glucose, baking soda (FORMULAS?)

30. A Chemical Formula • Symbols used to identify elements present • Tells ratio of element atoms present • Is constant for a particular compound

31. Chemical Formulas: • H2O H2O2 2 : 1 2 : 2 • CO2 H2SO4 1 : 2 2 : 1 : 4

32. Mass Ratio is constant • Hydrogen + Oxygen Water 2g : 16g 18g 1g : 8g Ratio: 1:8

33. Mg + O MgO 12g : 8g Ratio- 3:2 • CAN be broken down by chemical means e.g.(Water into hydrogen and oxygen)

34. Properties: • Each compound has its own unique set • Physical Properties … • Chemical properties … • Different from the elements that formed it e.g. O, H : colorless, odorless gases H2O : liquid. Na -metal, Cl -green gas, poisonous Sodium chloride- salt, colorless, essential for health.

35. Law of Conservation of Matter • Matter is neither created nor destroyed; It only changes from one form to another

36. Compds are classified by: • Their pH – How acidic or basic they are • If Organic (Carbon-containing) or Inorganic • The role they play - Proteins – enzymes, structural - Carbohydrates - Lipids – fats & oils - Nucleic acids

37. For more info… • Visit this photogallery of the elements http://chemistry.about.com/od/periodictableelements/ig/Element-Photo-Gallery.--98/