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Understanding Elements and Compounds: Key Properties and Classification

This comprehensive overview covers the characteristics and classification of pure substances, including elements and compounds. Elements consist of only one type of particle and cannot be separated by physical or chemical means, while compounds are formed by the chemical combination of two or more elements. The text highlights key properties such as melting point, boiling point, density, conductivity, and reactivity. It also distinguishes between metals, nonmetals, and metalloids, detailing their unique properties and roles in chemistry. Explore the periodic table and gain insights into various compounds and their significance.

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Understanding Elements and Compounds: Key Properties and Classification

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  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?

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

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

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

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

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

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

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

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

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

  16. Shiny • Poor conductors of thermal energy

  17. Compare Metals and Non Metals

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

  19. 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 …

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

  21. Symbols derived from Latin names of elements

  22. 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?

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

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

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

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

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

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

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

  30. 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.

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

  32. 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

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

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