1. Chapter 6 The Periodic Table and Periodic Law

2. The Periodic Table Periodic – means repeating pattern Remember: The Periodic Table is Your Friend!!

3. 6.1 History of the Periodic Table Mendeleev: Mendeleev: Arranged the periodic table according to atomic mass Arranged the periodic table according to atomic mass Similar chemical properties appeared in repeating intervals Similar chemical properties appeared in repeating intervals Page 175 – Mendeleev’s Periodic Table Page 175 – Mendeleev’s Periodic Table Only 63 elements were known at this time Only 63 elements were known at this time Gaps were left in the table but Mendeleev predicted that these elements did exist Gaps were left in the table but Mendeleev predicted that these elements did exist

6. 6.1 History of the Periodic Table Moseley: Moseley: Arranged the periodic table in order of increasing atomic number Arranged the periodic table in order of increasing atomic number Question: Can you find at least 2 places on Mosely’s periodic table that would be different if Mendeleev was right? (That is if the periodic table was organized by atomic mass not atomic number) Te and I, Co and Ni, Sg and Bh, Th and Pu, U and Np Te and I, Co and Ni, Sg and Bh, Th and Pu, U and Np

7. 6.1 History of the Periodic Table Periodic Law: Periodic Law: When elements are arranged in order of increasing atomic number there is a periodic pattern in their chemical and physical properties

9. Modern Periodic table Groups: vertical columns (1-18) Periods: horizontal rows (1-7) Arrangement: by increasing atomic number with groups containing similar chemical and physical properties

10. 5.2 Periodic Table and Electron Configuration The periodic table consists of 4 different “blocks” The periodic table consists of 4 different “blocks” s – block s – block p – block p – block d – block d – block f – block f – block Pg 183 – Figure 6.8 shows the blocks

12. S - Block Groups: 1 and 2 plus H and He Groups: 1 and 2 plus H and He Group 1 – Alkali Metals Group 1 – Alkali Metals Extremely reactive, seldom found free in nature Extremely reactive, seldom found free in nature Silvery, soft metal Silvery, soft metal Outer energy level = s 1 (H is 1s 1 ) Outer energy level = s 1 (H is 1s 1 ) Group 2 – Alkaline Earth Metals Group 2 – Alkaline Earth Metals Reactive, seldom found free in nature Reactive, seldom found free in nature Harder and stronger than Group 1 metals Harder and stronger than Group 1 metals Outer energy level = s 2 (He is 1s 2 )

14. Alkali Metals

15. P - Block Groups: 13 – 18 except He Groups: 13 – 18 except He Group 17 – Halogens (Diatomic X 2 ) Group 17 – Halogens (Diatomic X 2 ) Most reactive nonmetals Most reactive nonmetals React with metals to form “salts” React with metals to form “salts” Outer energy level = s 2 p 5 Outer energy level = s 2 p 5 Group 18 – Noble Gases Group 18 – Noble Gases Unreactive, most stable elements Unreactive, most stable elements Outer energy level = s 2 p 6 Outer energy level = s 2 p 6

16. D - Block Groups: 3-12 Groups: 3-12 Transition metals Transition metals High melting points, good conductors High melting points, good conductors Used for jewelry, power lines Used for jewelry, power lines Less reactive than Group 1 and 2 metals Less reactive than Group 1 and 2 metals Outer energy level: s and d have electrons Outer energy level: s and d have electrons

17. F – Block Bottom Two Rows: Inner Transition Metals Lanthanide – Lanthanide – Shiny metals Shiny metals Used in TV sets to emit color Used in TV sets to emit color Outer energy level: 6s and 4f Outer energy level: 6s and 4f Actinides – Actinides – Mostly manmade and radioactive Mostly manmade and radioactive Used for nuclear fuel, smoke detectors, A – bomb Used for nuclear fuel, smoke detectors, A – bomb Outer energy level: 7s and 5f Outer energy level: 7s and 5f

18. Periodic Trends Atomic Radius One half the distance between the nuclei of identical atoms that are bonded together One half the distance between the nuclei of identical atoms that are bonded together r

19. Atomic Radius Trend Atomic Radius Atomic Radius Decrease across a period from left to right Decrease across a period from left to right NaMgAlSiP Going across the period the number of protons and the number of outer electrons increase Inner shell electrons remain the same Therefore the positive charge of the nucleus across the period has a greater pull on the outer electrons

20. Atomic Radius Trend Atomic Radius Atomic Radius Increases down a group Increases down a group Going down a group a new electron “shell” or level is added. As a level is added, the atom gets larger. ** Francium has the largest atomic radius

21. Atomic Radius Trend

22. Ions Ion: atom with an unbalanced charge (#p ≠ #e) Cation: Cation: positively charged atom Lose electrons Metals Ex: Na 1+, Mg 2+ Ex: Na 1+, Mg 2+ Anion: Anion: negatively charged atom Gain electrons Nonmetals Ex: Cl 1-, O 2- Ex: Cl 1-, O 2-

23. Ionic Radii same as atomic radii only with ions same as atomic radii only with ionsPeriod: cation (metals) decrease left to right cation (metals) decrease left to right anion (nonmetals) decrease left to right anion (nonmetals) decrease left to rightGroup: Increase down a group

24. Ionic Radii

25. Ionization Energy The energy required to remove an electron from an atom The energy required to remove an electron from an atom Forms cations Forms cations The higher the ionization energy the harder it is to remove an electron The higher the ionization energy the harder it is to remove an electron Element + energy  A + + e - Ex: Na + energy  Na + + e - Hint: Test Question

26. Ionization Energy Ionization Energy Ionization Energy: Increases from left to right Increases from bottom to top ** Francium has the lowest ionization energy

27. Electron Affinity The energy released when adding an electron to an atom The energy released when adding an electron to an atom Creates anions Creates anions Element + e -  A - + energy Example: Cl + e -  Cl 1- + energy

28. Electron Affinity Electron Affinity: Increases from left to right Increases from bottom to top ** Fluorine has the highest electron affinity

29. Electronegativity measure of the ability of an atom in a chemical compound to attract electrons measure of the ability of an atom in a chemical compound to attract electrons N, O, and the halogens are the most electronegative

30. Electronegativity Electronegativity: Increases from left to right Increases from bottom to top ** Fluorine has the highest electronegativity

31. Periodic Trend Summary Atomic and Ionic Radius Increases Ionization Energy Increases Electron Affinity Increases Electronegativity Increases Atomic and Ionic Radius Increases