Periodic Trends in the Properties of the Elements Reactivity Metals: as you move down a family, reactivity goes up. As you move across a period, reactivity goes down. Brainiacs Video Nonmetals: as you move down a family, reactivity goes down. As you move across a period, reactivity goes up. Except for the Noble Gases!!!! Atomic Size Either volume or radius.
Treat atom as a hard marble. As you move down a column on the periodic table, the size of the atom increases. Valence shell farther from nucleus. As you move left to right across a period, the size of the atom decreases. Adding electrons to same valence shell. Valence shell held closer. Trends in Atomic Size, Continued Be (4p+ and 4e-) Mg (12p+ and 12e-) Ca (20p+ and 20e-) Group IIA 2e- Li (3p+ and 3e-) Be (4p+ and 4e-) B (5p+ and 5e-) C (6p+ and 6e-)
Period 2 2e- 1e- 3 p+ 2e- 4 p+ 2e- 3e- 5 p+ Li(3p+ and 3e-) Be(4p+ and 4e-) B(5p+ and 5e-) 6 p+ 2e- 4e- 8 p+ 2e- 6e- 10 p+ 2e- 8e- C(6p+ and 6e-) O(8p+ and 8e-) Ne (10p+ and 10e-) Choose the Larger Atom in Each Pair
C or O Li or K C or Al Se or I? PracticeChoose the Larger Atom in Each Pair.
1.N or F 2.C or Ge 3.N or Al 4.Al or Ge PracticeChoose the Larger Atom in Each Pair, Continued.
N or F, N is further left N or F C or Ge N or Al, Al is further down & left N or F C or Ge, Ge is further down N or F C or Ge N or Al Al or Ge?opposing trends Ionization Energy Minimum energy needed to remove an electron from an atom. Valence electron easiest to remove. M(g) + 1st IE M1+(g) + 1 e- M+1(g) + 2nd IE M2+(g) + 1 e- First ionization energy = energy to remove electron from neutral atom; 2nd IE = energy to remove from +1 ion; etc. Trends in Ionization Energy
As you move down a family, the IE gets smaller. Valence electron farther from nucleus. As you move left to right across a period, the IE gets larger. Trends in Ionization Energy, Continued ExampleChoose the Atom in Each Pair with the Higher First Ionization Energy
Al or S, Al is further left 1.Al or S 2.As or Sb 3.N or Si 4.O or Cl,opposing trends Al or S As or Sb N or Si, Si is further down and left Al or S As or Sb, Sb is further down PracticeChoose the Atom with the Highest Ionization Energy in Each Pair
1.Mg or P 2.Cl or Br 3.Se or Sb 4.P or Se PracticeChoose the Atom with the Highest Ionization Energy in Each Pair, Continued
1.Mg or P 2.Cl or Br 3.Se or Sb 4.P or Se ? Metallic Character How well an elements properties match the general properties of a metal. In general, metals are found on the left of the periodic table and nonmetals on the right. As you go left to right across the period, the elements become less metallic. As you go down a column, the elements become more metallic Trends in Metallic Character ExampleChoose the More Metallic Element in Each Pair
Sn or Te, Sn is further left Sn or Te P or Sb Ge or In S or Br?opposing trends Sn or Te P or Sb Ge or In, In is further down & left Sn or Te P or Sb, Sb is further down PracticeChoose the More Metallic Element in Each Pair
Sn or Te Si or Sn Br or Te Se or I PracticeChoose the More Metallic Element in Each Pair, Continued
Sn or Te Si or Sn Br or Te Se or I ? Electronegativity Measure of the pull an atom has on bonding electrons. Increases across the period (left to right). Decreases down the group (top to bottom). The larger the difference in electronegativity, the more polar the bond. Negative end toward more electronegative atom. d+H Fd- Electronegativity, Continued
2.1 1.0 0.9 0.8 0.7 1.5 1.2 1.3 1.1 1.4 1.6 1.8 1.7 1.9 2.2 2.4 2.0 2.5 3.0 3.5 4.0 2.8 Electronegativity, Continued Melting/Boiling Point
High melting/boiling point indicates strong bonding Middle of Periodic Table Low melting/boiling point indicates weak bonding Lowest MP/BP across period indicates completely filled orbital Edges of Periodic Table Noble gases have no bonding forces MP/BP unusually low Melting/Boiling Point