The Periodic Table Chapter 6

1. The Periodic TableChapter 6

2. Developing the Periodic Table p46 • Warm up: why are tables useful to us? • In the early 1800s, scientists began to classify elements. • German chemist Dobereiner grouped them into triads of similar properties. • English chemist Newlands, arranged them based on mass.

3. Developing the Periodic Table p46 • Russian chemist, Dimitri Mendeleev, organized elements based on mass and properties. • He found properties of elements repeat with increasing masses. • His table was accurate and he could predict properties for elements not yet discovered. ex. Germanium.

4. (DON’T WRITE) Germanium is located below silicon. Mendeleev predicted its properties based on this location in his table.

5. Modern Periodic Law p50 • Warm up: explain how the table reflects (shows us) the structure of the atom. • Henry Moseley revised Mendeleev’s table and used atomic number instead of mass. • Periodic law: properties of elements are periodic functions of atomic numbers.

6. Modern Periodic Table p50 • Rows on the table are called PERIODS • Columns on the table are called GROUPS or FAMILIES • There are 7 periods and 18 groups. • Electron config. are repeated in periods. • similar e- config. in the same group. • Elements in groups are also listed in order of their increasing n.

7. Octet Rule p50 • Eight electrons in an outer energy level make an atom stable. (2 in s and 6 in the p) • True for all except He & H • atoms react with one another to obtain these 8 valence e-. • Some atoms gain or lose e- (ions) and some share e- (molecules).

8. Periodicity Graphing Activityp49 • Use class set of graphs to answer: • What happens to the atomic radius as you move across a period? Down a period? • What happens to the valence electrons as you go across a period? Down a period? • Do properties of elements repeat on the periodic table? Use CREW.

9. Periodic Trends p52 • Warm up: describe the trend that our climate is experiencing. • We can use the Periodic Table to predict properties of elements

10. Atomic Radius (p52) • As energy level increases , the size of the electron cloud i. Size of atoms moving down table. • Atoms by one proton for each element going across. This pulls the e- cloud in tighter= atomic radius. • General rule: atomic size largest at bottom left corner.

11. Sketch picture on p51. • (use ¼ pg)

12. Trends in Oxidation Numbers p52 • This is the charge an element would have if it had an octet (8 ve-) • (talk about valence electrons) • Remember adding electrons is negative and removing electrons is positive.

13. Oxidation numbers- Look at periodic table handout. sketch p 51 1+ 0 2+ or 4+ 2- 3- 1- 2+ 3+ Tend to have more than one oxidation number 3+ 3+ or 4+

14. Ionization Energy p 52 • The energy required to remove an e- from an atom. • As atoms get closer to an octet, the harder it is to remove electrons. As electrons get further from the nucleus, the easier it is to remove them. • Ionization energy greatest at top right corner

15. (LEFT PAGE) draw on p51

16. Electronegativity (p52) • Electronegativity is a measure of an atom’s attraction for another e-. • Metals are low.(need to get rid of extra e-) • Nonmetals are high.(need more for octet) • As atoms get larger, harder to attract e- because they are further from nucleus.

17. Electronegativity (p51) • Increases across table with the arrows (draw on pg, ¼ pg)

18. Organizing Information on the Periodic Table p54 • Warm up: Explain something new that you learned about the periodic table. • label the following on your table : Group 1 Alkali metals Group 2 Alkaline earth metals Group 16 Chalcogens Group 17 Halogens Group 18 Noble gases Sc – Uub Transition metals La – Lu Lanthanoids Ac – Lr Actinoids Inner transition metals

19. Organizing Information on the Periodic Table p54 • Draw a stair step dark line starting between B and Al. • Label the left side: metals • Label the right side: nonmetals • Write METALLOID (semimetal) along stair step line.

20. Basic Properties of Metals, Nonmetals, and Metalloids • Metals: 1. Hard and shiny. Malleable. 2. Conduct heat and electricity well. • Nonmetals: 1. Generally gases or brittle solids. 2. If solid, dull surface. 3. Good insulators. • Metalloids: 1. Properties of both metals and non.

21. Review

22. When graphed, atomic radii demonstrates a periodic trend

23. METAL 1. Low 1st ionization energy. 2. Located on left side of Periodic Table. 3. Form positive ions.(wants to give up extra e- to have an octet on previous energy level) Nonmetal 1. High 1st ionization energy. 2. Located on the right side of Periodic Table. 3. Form negative ions.(want to get more electrons to get octet) Ionization Energy

24. Multiple Ionization Energies • Additional e- can be lost from an atom and the ionization energies can be measured. IONIZATION ENERGIES (kilojoules per mole) Element 1st 2nd 3rd 4th 5th H 1312.0 He 2372.3 5220 Li 520.2 7300 11750 Be 899.5 1760 14850 20900 B 800.6 2420 3660 25020 32660

25. In Summary • Periodic table is a chart of elements in which the elements are arranged based on their e- configurations which dictates their properties. • Moving down a group in the periodic table, atomic radii becomes larger because more energy levels are needed for more e-.

26. In Summary • As the size becomes larger, the e- are located farther away from the positive center. • This decreases the affinity of that atom to hold on to these outer e-, thus decreasing e- affinity. • Ionization energy is low because it is easy for the atom to lose these outer e-.

27. In Summary • Moving across a period in the periodic table, atomic radii becomes smaller because the energy levels of periods are the same but the positive centers of atoms increase. This pulls the e- cloud closer to the nucleus, making the atom smaller. • Ionization energy and e- affinity increases for these smaller atoms.

28. THE END