1. The Periodic Table Arranging the Elements

2. Trends Trend = pattern What trends to you see from right to left? What trends to you see from top to bottom?

3. Right to Left the body of each character in each row is the same shape as you move there is a finger added each time Top to Bottom In the first two columns, as you move down another hair is added to the head In the third column, the feet get longer In the fourth column, there is an additional line added in the body

4. To Review: Finding Your Way Around the P.T. Period = row (across) Period = row (across) Group = column (down) Group = column (down) Like coordinates on a grid Like coordinates on a grid

5. Actual Shape of the Periodic Table If the Lanthanides and Actinides are put in the table and not left underneath

6. Group = Column

7. Period = Row

8. Mendeleev’s Periodic Table 1860’s: Mendeleev ordered elements by atomic mass Predicted properties of unknown elements based on properties of surrounding elements But some elements were still out of place—he thought his calculations were wrong

9. What element is it? Mendeleev’s Predictions Actual Properties Atomic Mass 7272.6 Density5.5g/cm 3 5.3g/cm 3 AppearanceDark gray metalGray metal Melting Point High melting pt937 C The unknown element turned out to be Germanium

10. Proton Discovered 1914—Proton discovered and understood British scientist Henry Moseley arranged elements based on atomic number

11. Periodicity Element properties show “periodicity”—regular, repeating pattern Element properties show “periodicity”—regular, repeating pattern Since 1914 more elements have been discovered Since 1914 more elements have been discovered All follow the periodic law: chemical and physical properties of elements are periodic functions of their atomic number All follow the periodic law: chemical and physical properties of elements are periodic functions of their atomic number

12. Periodicity of Density

13. Metallic Character

14. Atomic Radius Trend across a period? Trend across a period? Trend down a group? Trend down a group?

15. Reactivity Reactivity (how intensely an element reacts with other substances) Reactivity (how intensely an element reacts with other substances) Elements react by taking, giving, or sharing electrons to get a full shell Elements react by taking, giving, or sharing electrons to get a full shell

16. Melting Point Metals: basically decrease down the group Metals: basically decrease down the group Non-metals: basically increase down the group Non-metals: basically increase down the group

17. Density

19. Spiral Periodic Table