Problem 1.1
Use the Handbook of Chemistry and Physics as s data source to
indicate the nature of the periodic variation of the properties of the
elements in Groups 1, 2, 11, 12, 15, 16, and 18: (a) melting points;
(b) boiling points; (c) formulas of oxides; (d) colored
oxides.
Answer:
(a) melting points
Group 1: Li, 180.5; Na, 98; K, 63.5;Rb, 39; Cs, 28.5. decreasing
Group 2: Be, 1287; Mg, 650; Ca, 842; Sr, 777; Ba, 727. decreasing, Mg odd
Group 11: Cu, 1085; Ag, 962; Au, 1064. ?
Group 12: Zn, 420; Cd, 321; Hg, -39. decreasing
Group 15: N, -246; P, 44; As, 817; Sb, 631; Bi, 209. ?
Group 16: O, -219; S, 115; Se, 221; Te, 450; Po, 254. increasing until Po
Group 18: He, does not solidify; Ne, -249; Ar, -189; Kr, -157; Xe, -112.
increasing
(b) boiling points - trends similar to melting point.
Group 1: Li, 1342; Na, 883; K, 759;Rb, 688; Cs, 671.
Group 2: Be, 2471; Mg, 1090; Ca, 1484; Sr, 1382; Ba, 1897.
Group 11: Cu, 2562; Ag, 2162; Au, 2856.
Group 12: Zn, 907; Cd, 767; Hg, 357.
Group 15: N, -196; P, 280.5; As, sublimes; Sb, 1587; Bi, 271.
Group 16: O, -183; S, 445; Se, 685; Te, 988; Po, 962.
Group 18: He, -269; Ne, -246; Ar, -186; Kr, -153; Xe, -108.
(c) formula of oxides, mostly the same down a group.
Group 1: Li, Li2O; Na, Na2O; K, K2O;Rb, Rb2O; Cs, Cs2O.
Group 2: Be, BeO; Mg, MgO; Ca, CaO; Sr, SrO; Ba, BaO, BaO2.
Group 11: Cu, CuO; Ag, Ag2O; Au, Au2O3.
Group 12: Zn, ZnO; Cd, CdO; Hg, HgO.
Group 15: N, N2O, NO, NO2, N2O3, N2O4, N2O5; P, P2O3; As, As2O3; Sb, Sb2O3; Bi, Bi2O3.
Group 16: O, O3; S, SO2, SO3; Se, SeO2, SeO3; Te, ?; Po, PoO2.
Group 18: He, no oxides; Ne, no oxides; Ar, no oxides; Kr, no oxides;
Xe, XeO3, XeO4.
(d) colored oxides - increasingly colored down a group.
Group 1: Li, white; Na, white; K, gray;Rb, yellow-brown; Cs, yellow-orange.
Group 2: Be,white ; Mg, white; Ca, gray-white; Sr, white; Ba, yellow-white.
Group 11: Cu, black; Ag, brown-black; Au, brown.
Group 12: Zn, white; Cd, brown; Hg, red-yellow.
Group 15: N, N2O colorless, NO colorless, NO2 red-brown, N2O3 blue, N2O4 colorless, N2O5 colorless; P, white; As, white; Sb, white; Bi, yellow.
Group 16: O, blue; S, colorless; Se, white; Te, ?; Po, yellow.
Group 18: He, no oxides; Ne, no oxides; Ar, no oxides; Kr, no oxides;
Xe, white, yellow.