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7.6: Metals, Nonmetals, and Metalloids

7.6: Metals, Nonmetals, and Metalloids. Text, P. 252. Metals Metallic character refers to the properties of metals shiny or lustrous malleable and ductile oxides form basic ionic solids form cations in aqueous solution Metallic character increases down a group

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7.6: Metals, Nonmetals, and Metalloids

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  1. 7.6: Metals, Nonmetals, and Metalloids Text, P. 252

  2. Metals • Metallic character refers to the properties of metals • shiny or lustrous • malleable and ductile • oxides form basic ionic solids • form cations in aqueous solution • Metallic character increases down a group • Metallic character decreases across a period • Metals have low ionization energies • Most neutral metals are oxidized rather than reduced • form cations Chapter 7

  3. Most metal oxides are basic: • Metal oxide + water  metal hydroxide • Nonmetals • Nonmetals are more diverse in their behavior than metals • Properties are opposite those of metals • Compounds composed only of nonmetals are molecular • When nonmetals react with metals, nonmetals tend to gain electrons: • metal + nonmetal  salt Chapter 7

  4. Most nonmetal oxides are acidic: • nonmetal oxide + water  acid • Nonmetal oxide + base  salt + water • The greater the nonmetallic character of the central atom, the stronger the acidic character of the oxide • Metalloids • Metalloids have properties that are intermediate between metals and nonmetals • Si has a metallic luster but it is brittle • Semiconductors Chapter 7

  5. 7.7: Group Trends for the Active Metals • Group 1A: The Alkali Metals • Alkali metals are all soft • Chemistry dominated by the loss of their single s electron: • M  M+ + e- • Reactivity increases down the group • Alkali metals react with water to form MOH and hydrogen gas: • 2M(s) + 2H2O(l)  2MOH(aq) + H2(g) Chapter 7

  6. Alkali metals produce different oxides when reacting with O2: • 4Li(s) + O2(g)  2Li2O(s) (oxide) • 2Na(s) + O2(g)  Na2O2(s) (peroxide) • K(s) + O2(g)  KO2(s) (superoxide) • (Rb and Cs, too) • Alkali metals: Flame tests • The s electron is excited by the flame and emits energy when it returns to the ground state Chapter 7

  7. Li line: 2p 2s transition Na line (589 nm): 3p 3s transition K line: 4p 4s transition Chapter 7

  8. Text, P. 257 Chapter 7

  9. Group 2A: The Alkaline Earth Metals • Alkaline earth metals are harder and more dense than the alkali metals • The chemistry is dominated by the loss of two s electrons: • M  M2+ + 2e- • Mg(s) + Cl2(g)  MgCl2(s) • Increasing activity down the group: • Be does not react with water • Mg will only react with steam • Ca, Sr and Ba: • M(s) + 2H2O(l)  M(OH)2(aq) + H2(g) Chapter 7

  10. Group 2A: The Alkaline Earth Metals Text, P. 260 Chapter 7

  11. 7.8: Group Trends for Selected Nonmetals • Hydrogen • Colorless diatomic gas, H2 • High IE because there are no inner electrons • It can either gain another electron to form the hydride ion, H-, or lose its electron to become H+: • 2Na(s) + H2(g)  2NaH(s) • 2H2(g) + O2(g)  2H2O(g) • H+ is a proton • The aqueous chemistry of hydrogen is dominated by H+(aq) Chapter 7

  12. Group 16: The Oxygen Group • Metallic character increases down a group (O2is a gas, Te is a metalloid, Po is a metal) • Two important forms of oxygen: O2 and ozone, O3 • Ozone can be prepared from oxygen: • 3O2(g)  2O3(g) H = +284.6 kJ. • Ozone is pungent and toxic Chapter 7

  13. Group 16: The Oxygen Group Text, P. 261 Chapter 7

  14. Oxygen (O2) is a potent oxidizing agent • O2-ion has a noble gas configuration • There are two oxidation states for oxygen: 2- and 1- • Sulfur is another important member of this group • Most common form of sulfur is yellow S8 • Sulfur tends to form S2- in compounds (sulfides) • Allotropes: different forms of the same element in the same state Chapter 7

  15. Group 17: The Halogens • The chemistry of the halogens is dominated by gaining an electron to form an anion: • X2 + 2e- 2X- • Fluorine is one of the most reactive substances known • All halogens consists of diatomic molecules, X2 Chapter 7

  16. Group 17: The Halogens Text, P. 262 Chapter 7

  17. Chlorine is the most industrially useful halogen • Produced by the electrolysis of brine (NaCl): • 2NaCl(aq) + 2H2O(l)  2NaOH(aq) + H2(g) + Cl2(g) • Hydrogen compounds of the halogens are all strong acids with the exception of HF Chapter 7

  18. Group 18: The Noble Gases • These are all nonmetals and monatomic • Unreactivebecause they have completely filled s and p sub-shells • In 1962 the first compound of the noble gases was prepared: XeF2, XeF4, and XeF6 • Xe has a low enough IE to react with substances that readily remove electrons • To date the only other noble gas compounds known are KrF2 and HArF • “Argon hydrofluoride” Chapter 7

  19. Group 18: The Noble Gases Text, P. 263 Chapter 7

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