Organizing the elements Objective: How are the elements organized?

1. Organizing the elements Objective: How are the elements organized?

2. Mendeleev developed the first periodic table of the elements. An element's properties can be predicted from its location in the table. Link to a Periodic Table.

3. Mg Br Cl C H Fe Ca P Zn The modern periodic table Elements are arranged according to atomic number. Periods (7) = horizontal rows of elements Group (18 family) = vertical column of elements with similar properties Zig zag line = separates metals from nonmetals

4. http://www.echalk.co.uk/Science/chemistry/periodicTableGame/periodicTable.htmlhttp://www.echalk.co.uk/Science/chemistry/periodicTableGame/periodicTable.html Why the periodic table works? It works because it's based on the structure of the atoms, especially the valence electrons. All the elements in a family all have the same number of valence electrons.

5. What is a metal? • An element with specific properties: shiny, ductile, malleable, and good conductors of heat and electricity • Usually have 3 or less electrons in outer shell and give up Electrons when forming compounds. • They are found to the left of the zigzag line • Examples: lithium, iron, gold, silver

6. Review Terms: • Malleable – the ability to be pounded into thin sheets. Ex: aluminum • Ductile – the ability to be pulled into a thin wire. Ex: copper

7. Alloys • An alloy is a substance that is a mixture of two or more metals. • Examples: bronze (copper with tin) and brass (copper with zinc)

8. Metals in the periodic table Alkali metals (Group 1) • Are the most reactive • Are never found aselements only in compounds • Are very soft and shiny • 1 valence electron

9. Alkaline earth metals (Group 2) • Are not as reactive as Group 1 metals • Are fairly hard, gray-white • Good conductors of electricity • 2 valence electrons

10. Transition metals (Group 3) • Form a bridge between the (left side) very reactive and less reactive (right side) • Are good conductors of electricity • 2 valence electrons

11. Lanthanides and actinides • Rare earth metals (periods 6 and 7). • Valence electrons: 2 • Lanthanides are soft, malleable, shiny metals with high conductivity • Actinides exist in very small amounts except for thorium and uranium

12. O O O C N C Cl • What are nonmetals? • An element with properties opposite of metals: often gases or dull, brittle solids with low melting points • Found to the right of the zigzag line • Forms compounds with metals (e.g., NaCl, CO2) • Combines with other nonmetals to form diatomic molecules (e.g., O2, N2, H2)

13. Properties of Non-Metals (cont.) • Have five or more electrons in their outer shell. • Poor Conductors • They can share or gain electrons when forming compounds.

14. Families of nonmetals • Carbon family: AKA: tetrels – from Latin tetra (four) • 4 valence electrons

15. Families of nonmetals • Nitrogen family: AKA: pnictide – from Greek pnigein (to choke) • 5 valence electrons

16. Families of nonmetals • Oxygen family: AKA: chalcogens – from Greek chalkos (ore) • 6 valence electrons

17. More families of nonmetals • Halogen family: reactive; found in nature as compounds or diatomic molecules • 7 valence electrons

18. More families of nonmetals • Noble gases: odorless, colorless gases that are not reactive • 8 valence electrons

19. More families of nonmetals • Hydrogen: a very reactive nonmetal because it has 1 valence electron. • This is why it is in the column with the alkali metals. • However, it is not classified as an alkali metal.

20. Metalloids • Have characteristics of both metals and nonmetals • Seven elements on the border between metals • and nonmetals • Great conductors of electricity • Examples: B, Si, As, Te, At, Ge, Sb