1. The Periodic Table Chapter 5 Notes

2. Mendeleev ● Designed first periodic table (1869) ● Arranged mostly by increasing atomic mass ● Elements in the same column have similar properties

3. Moseley ● Arranged by increasing atomic number

4. Periodic Law ● Elements’ physical and chemical properties show a periodic [“repeating”] pattern when arranged by atomic number

5. ● COLUMN = Group or Family o Similar properties based on the same number of valence electrons o Numbered 1-18 or with Roman numerals ● ROW = Period

6. Valence electrons ● Electrons in the outermost shell ● Octet Rule = all atoms want 8 valence electrons to achieve stability o Exceptions: H, He

7. Families of the Periodic Table

8. Alkali Metals ● Soft ● Most reactive metals

9. Noble Gases ● very UNreactive ● “inert”

10. Halogens ● Most reactive nonmetals

11. Metals ● luster/shiny, good conductors of heat & electricity, malleable, ductile ● LEFT SIDE of periodic table

12. Nonmetals ● not shiny, poor conductors, not malleable or ductile, brittle ● RIGHT SIDE of periodic table

13. Metalloids ● “semi-metals” ● some properties of metals, some of nonmetals ● touch ZIG-ZAG LINE

14. Periodic Trends

15. Atomic Radius ● Distance from the nucleus to the outer electrons ● Decreases across a row ● Increases down a column

17. Explanation of Atomic Radius increasing down a column

19. Explanation of Atomic Radius decreasing across a row

21. Electronegativity ● Ability of an atom to attract electrons to itself o Increases across a row o Decreases down a column

22. Ionization Energy ● Energy needed to remove an electron ● Increases across a row ● Decreases down a column

23. Electron Affinity ● How much an atom wants to gain an electron o Decreases down a column o Increases across a row

24. Think about Corners

25. Practice- Circle your answer choice Larger atomic radius? 1) Mg or Sr 2) Mg or S Larger electronegativity? 3) P or Sb 4) Ge or Br Larger ionization energy? 5) Ca or Se 6) Ca or Ra

26. Ion Size ● Cation – atom loses electron o Atom gets smaller ● Anion – atom gains electron o Atom gets bigger

27. Exampl e of Ion Size