1. 1869 DMITRI MENDELEEV Arranged the elements by increasing atomic mass, and noticed properties repeat regularly Left a space if an element didn’t belong in a particular column THE PERIODIC TABLE 1H-1 (of 10)

2. Mendeleev stated the PERIODIC LAW: The properties of the chemical elements are not arbitrary, but vary with their atomic masses in a systematic way Mendeleev was able to predict properties of undiscovered elements However, accurate atomic mass determinations showed errors in the table 1H-2 (of 10)

3. 1912 HENRY MOSELEY Measured the frequency of x-rays from excited atoms Found they were proportional to the ATOMIC NUMBER of the atoms, not the atomic mass 1H-3 (of 10)

4. 1912 HENRY MOSELEY This work changed the PERIODIC LAW: The properties of the chemical elements vary with atomic number 1H-4 (of 10)

5. PERIOD or SERIES – A rowGROUP or FAMILY – A column Elements in columns have similar properties because they have the same number of valence electrons 1H-5 (of 10)

6. PERIODIC TRENDS OF ATOMS The attraction of either (1) outer shell electrons or (2) free electrons to the nucleus of an atom depends on (1)The number of protons in nucleus (2)The number of energy levels blocking or SHIELDING the nucleus from the outer shell or free electrons 1H-6 (of 10)

7. 1)ATOMIC RADIUS – The distance from the nucleus to the outer shell of an atom 1H-7 (of 10)

8. PERIODIC TRENDS IN ATOMIC RADII Period – The atomic radii decrease moving to the right the outer shell electrons are attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the same Group – The atomic radii increase moving down a column even though the nuclear charge is increasing, the outer shell electrons are more shielded from the nuclear charge Atom with the largest atomic radius ? Atom with the smallest atomic radius? 1H-8 (of 10)

9. 1H-9 (of 10)

10. EXCEPTIONS TO THE TRENDS IN ATOMIC RADII Group Atoms in the 5d sublevel section of the periodic table are not larger than atoms in the 4d sublevel section Radii V(Z = 23)0.122 nm Nb(Z = 41)0.134 nm 0.134 nm IncreasingDecreasingFactor 1 more EL18 more p + 1 more EL32 more p + V(Z = 23) Nb(Z = 41) Ta(Z = 73) This is called the LANTHANIDE CONTRACTION 1I-10 (of 10)

12. 2)IONIZATION ENERGY (IE) – The energy change for the removal of an electron from a gaseous atom X (g) → X + (g) + e - Endothermic – A process in which energy is absorbed (∆E is positive) Exothermic – A process in which energy is released (∆E is negative) Ionization Energies are always endothermic 1I-1 (of 15)

13. SUCCESSIVE IONIZATION ENERGIES Mg (g)→ Mg + (g) + e - 1 st IE = 736 kJ/mol Mg + (g)→ Mg 2+ (g) + e - 2 nd IE = 1,451 kJ/mol Mg 2+ (g)→ Mg 3+ (g) + e - 3 rd IE = 7,728 kJ/mol Mg 3+ (g)→ Mg 4+ (g) + e - 4 th IE = 10,534 kJ/mol Successive ionization energies always increase because successive ions have less e - -e - repulsion 1I-2 (of 15)

14. SUCCESSIVE IONIZATION ENERGIES Mg (g)→ Mg + (g) + e - 1 st IE = 736 kJ/mol Mg + (g)→ Mg 2+ (g) + e - 2 nd IE = 1,451 kJ/mol Mg 2+ (g)→ Mg 3+ (g) + e - 3 rd IE = 7,728 kJ/mol Mg 3+ (g)→ Mg 4+ (g) + e - 4 th IE = 10,534 kJ/mol Successive ionization energies always increase because successive ions have less e - -e - repulsion 7,728 kJ/mol 10,534 kJ/mol Small ionization energies occur when removed e - s are valence e - s, which are the most shielded from the nuclear charge 1I-3 (of 15)

15. Determine which atom is sodium and which atom is aluminum 1 st IE = 578 kJ/mol 2 nd IE = 1,817 kJ/mol 3 rd IE = 2,745 kJ/mol 4 th IE = 11,577 kJ/mol 1 st IE = 496 kJ/mol 2 nd IE = 4,562 kJ/mol 3 rd IE = 6,912 kJ/mol 4 th IE = 9,543 kJ/mol NaAl Atom 2Atom 1 1I-4 (of 15)

16. PERIODIC TRENDS IN 1 st IONIZATION ENERGIES Period – The 1st IE increases moving to the right the removed electron is attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the same Group – The 1 st IE decreases moving down a column even though the nuclear charge is increasing, the removed electron is more shielded from the nuclear charge Atom with the highest 1 st IE ?Atom with the lowest 1 st IE? 1I-5 (of 15)

17. 1I-6 (of 15)

18. EXCEPTIONS TO THE TRENDS IN 1 st IONIZATION ENERGIES Period LiBeBCNOFNe 519900108814061682208051990079910881406131416822080 1s2s2p B ↑↓↑↓↑ _________ ___ ___ The removed e - for B is in a p orbital, whereas the removed e - for Be is in an s orbital - e - s in p orbitals are more shielded from the nuclear charge than e - s in s orbitals 1I-7 (of 15)

19. EXCEPTIONS TO THE TRENDS IN 1 st IONIZATION ENERGIES Period LiBeBCNOFNe 51990079910881406131416822080 The removed e - for O is paired and experiencing e - -e - repulsion, whereas the removed e - for N is not ↑↓↑↓↑↓ ↑ ↑ _________ ___ ___ O 1s2s2p 1I-8 (of 15)

20. 3)ELECTRON AFFINITY (EA) – The energy change for the addition of an electron to a gaseous atom X (g) + e - → X - (g) Electron Affinities are always exothermic 1I-9 (of 15)

21. PERIODIC TRENDS IN ELECTRON AFFINITIES Period – EA increases (becomes more exothermic) moving to the right a free electron is attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the same (except noble gases) Group – EA decreases (becomes less exothermic) moving down a column even though the nuclear charge is increasing, a free electron is more shielded from the nuclear charge 1I-10 (of 15)

22. 1I-11 (of 15)

23. EXCEPTIONS TO THE TRENDS IN 1 st ELECTRON AFFINITIES Group In the p block of the periodic table, adding e - s to small atoms (those in the 2 nd period) results in large e - -e - repulsion, so their 1 st EA’s are slightly less exothermic than atoms in the 3 rd period F Cl-349 kJ/mol Br -343 kJ/mol I-295 kJ/mol -328 kJ/mol ← element with the highest EA 1I-12 (of 15)

24. EXCEPTIONS TO THE TRENDS IN 1 st ELECTRON AFFINITIES Period KCaGaGeAsSeBrKr -49-76-116-195-325-49~0-76-116-75-195-325~0 The added e - will go into an orbital of a new sublevel, where it will be very shielded from the nuclear charge ↑↓ ______ ___ ___ ___ ___ ___ ___ ___ Ca [Ar] 4s3d4p ↑↓↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ______ ___ ___ ___ ___ ___ ___ ___ Kr [Ar] 1I-13 (of 15)

25. EXCEPTIONS TO THE TRENDS IN 1 st ELECTRON AFFINITIES Period KCaGaGeAsSeBrKr -49~0-76-116-75-195-325~0 The added e - will experience e - -e - repulsion ↑↓↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ ↑ ↑ ______ ___ ___ ___ ___ ___ ___ ___ As [Ar] 4s3d4p 1I-14 (of 15)

26. EXCEPTIONS TO THE TRENDS IN 1 st ELECTRON AFFINITIES Period KCaGaGeAsSeBrKr -49~0-76-116-75-195-325~0 What other two elements in the 4 th period would you expect to have low electron affinities? 1I-15 (of 15)

28. Bismuth (Z = 83) – The element of highest atomic number with at least one stable isotope Plutonium (Z = 94) – The element of highest atomic number found naturally on Earth 1J-13 (of 13)

29. METALS Physical Properties – Low number of valence electrons, metallic luster, malleable, ductile, conductors of heat and electricity Solids are brilliant white (or silver) except copper (red) and gold (yellow), mercury is a liquid Chemical Properties – Due to the low ionization energies of their valence electrons, they can lose their valence electrons to produce positive ions (called CATIONS) 1J-1 (of 13)

30. Group 1 -Alkali Metals Group 2 -Alkaline Earth Metals Group 11-Coinage Metals 8, 9, 10 -Fe-Co-Ni Triad - The Ferromagnetic Metals 8, 9, 10-Noble Metals (Ru, Rh, Pd, Os, Ir, Pt) d Block-Transition Metals f Block-Inner Transition Metals (Lanthanides and Actinides) 1J-2 (of 13)

31. Metal Hardness Group 1 metals are soft, hardness increases to Group 6, and then hardness decreases to Group 16 1J-3 (of 13)

32. Metal Activity Group 1 metals are extremely active, and activity decreases to Group 11, with the Noble Metals, Coinage Metals, and Hg being very inactive Al and Zn are very active, and activity decreases down and to the right 1J-4 (of 13)

33. NONMETALS Physical Properties – High number of valence electrons, opposite of metals Some are crystalline solids, bromine is a liquid, and some are gases Chemical Properties – Due to their highly exothermic electron affinities, they can gain electrons until their outer shells are full to produce negative ions (called ANIONS) 1J-5 (of 13)

34. Group 18 -Noble Gases Group 17 -Halogens Hydrogen-A group of its own in that it can form 1+ and 1- ions 1J-6 (of 13)

35. Hydrogen-Colorless gas (H 2 ) Helium-Colorless gas (He) 1J-7 (of 13)

36. ALLOTROPES – Forms of an element with different interatomic bonding, so different properties Boron -Crystalline brown Carbon-Crystalline as diamond, graphite, or buckminster- fullerene; amorphous as charcoal 1J-8 (of 13)

37. Nitrogen-Colorless gas (N 2 ) Oxygen -Colorless gas allotropes dioxygen (O 2 ) and ozone (O 3 ) Phosphorus-Crystalline red, white (P 4 ), and black allotropes Sulfur-Crystalline yellow (S 8 rings) and other allotropes (S 8 chains) 1J-9 (of 13)

38. Fluorine-Pale yellow-green gas (F 2 ) Chlorine -Yellow-green gas (Cl 2 ) Bromine-Orange liquid (Br 2 ) Iodine- Crystalline black (I 2 ), sublimes to violet vapor Noble Gases-Colorless monatomic gases 1J-10 (of 13)

39. Nonmetal Activity Group 17 nonmetals are extremely active, and activity decreases down and to the left H is active, and the Noble Gases are inert 1J-11 (of 13)

40. METALLOIDS Intermediate number of valence electrons, properties of metals and nonmetals 1J-12 (of 13)