Representative Elements Big Idea: The structure of atoms determines - PowerPoint PPT Presentation

Chapter 18: The Representative Elements Big Idea: The structure of atoms determines their o Hydrogen properties; o Group 1A consequently, the o Group 2A behavior of elements is o Group 3A related to their o Group 4A location in the o Group 5A periodic table. In o Group 6A general nonmetallic o Group 7A character becomes o Group 8A more pronounced toward the right of the periodic table. 1

The Representative Elements 2 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

The Representative Elements 3 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Hydrogen  Electron configuration is 1s 1 (similar to the electron configurations of group 1A elements)  Classified as a non metal  Therefore it doesn’t fit into any group 4 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Hydrogen  Most H is made up of only two particles (an electron and a proton)  H is the most abundant element in the universe and accounts for 89% of all atoms  Little free H on earth  H 2 gas is so light that it moves very fast and can escape the Earth’s gravitational pull  Need heavier planets to confine H 2 5 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Group 1A The Alkali Metals  Electron configuration is ns 1 (n = period number).  Lose their valence e - easily (great reducing agents).  Most violently reactive of all the metals.  React strongly with H 2 O(l); the vigor of the reaction increases down the group.  The alkali metals are all too easily oxidized to be found in their free state in nature. 6 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Group 1A Lithium Sodium  Strong polarizing power  Mined as rock salt which is a deposit of  Forms bonds with sodium chloride left as highly covalent ancient oceans character evaporated  Used in ceramics,  Extracted using Lubricants, Medicine electrolysis of molten (lithium carbonate NaCl (Downs process) (treatment for bipolar disorder)) Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 7

Group 1A Important Group  NaCl  NaOH  NaHCO 3 (Baking Soda)  HCO 3 - (aq) + HA(aq)  A - (g) + H 2 O(l) +CO 2 (g)  The weak acid (HA) must be present in the dough; Some weak acids are sour milk, buttermilk, lemon jucie, or vinegar. Not ote: Baking powder contains a solid weak acid as well as the hydrogen carbonate therefore CO 2 (g) is released when water is added  KNO 3 ∆ 2KNO 2 (s) + O 2 (g)  2KNO 3 (s) 8 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Group 1A Common Reactions  Reaction with H  Reaction with Halogens  2M + H 2  2MH  2M + X 2  2MX X 2 is any halogen  Reaction with N  Reactions with Oxygen  6Li + N 2  2Li 3 N Li only  4Li + O 2  2Li 2 O Need excess Oxygen  2Na + O 2  Na 2 O 2  Reaction with Water  M + O 2  MO 2  2M + 2H 2 O  2MOH + H 2 M = K, Rb, or Cs  Reaction with Ions  2M + 2H +  2M+ + H 2 9 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Group 2A  Electron configuration is The Alkaline Earth Metals ns 2 (n is the period number).  All group 2 element are too reactive to occur in the uncombined state in nature.  Usually found as doubly charged cations.  All group 2 elements except for beryllium react with water and the vigor of the reaction increases going down the group. Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 10

Group 2A Beryllium Magnesium Calcium  Has some non  Found in sea  Found in sea metal tendencies water water  The gemstone  Mg is present in  The element of emerald contains the chlorophyll rigidity and Be but its green molecule construction color is caused (bones, shells,  Forms protective by Cr 3+ ions concrete, mortar, oxide limestone  Obtained by the  Obtained by (buildings)…) electrolytic either chemical or reduction of electrolytic molten beryllium reduction of its chloride compounds Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 11

Group 2A Important Compounds  Mg(OH) 2 (milk of magnesia)  MgSO 4 (epsom salt)  Chlorophyll  CaCO 3 (calcium carbonate) Δ CaO(s) + CO 2 (g)  CaCO 3 (s)  CaO (quick lime)  CaO(s) +H 2 O(l)  Ca 2+ (aq) + 2OH - (aq)  Ca(OH) 2 (slack lime)  Concrete Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 12

Group 2A Common Reactions  Reaction with  Reaction with N Halogens  3M + N 2  M 3 N 2 High temperatures  M + X 2  MX 2 X 2 is any halogen  Reaction with Water  Reaction with Oxygen  M +2H 2 O  M(OH) 2 + H 2  2M + O 2  2MO  Reaction with Ions  M + 2H +  M 2+ + H 2  Reaction with H  M + H 2  MH 2 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 13

Group 3A  Electron configuration is ns 2 np 1 (n is the period number).  Boron and aluminum almost always have an oxidation number of +3.  The heavier elements of the group are more likely to keep their s electrons and can have oxidation numbers of +1 or +3. Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 14

Group 3A Boron Aluminum  High ionization energy  Most abundant metallic element in the Earth’s crust  Metalloid  Low density  Forms covalent bonds  Excellent electrical  Tends to form compounds conductor that have incomplete octets or are electron  Commercial source of deficient aluminum is bauxite (Al 2 O 3 ·xH 2 O where x ranges  Mined as borax and kernite from 1 to 3) (Na 2 B 4 O 7 ·xH 2 O x = 10 or 4) Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 15

Group 3A Important Compounds  B(OH) 3 (Boric Acid)  Na 2 B 4 O 7 ·10H 2 O(borax)  Al 2 O 3 (Aluminum oxide or alumina) Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 16

Group 3A Common Reactions  Reactions with N  Reaction with Halogens  2M +N 2  2MN  2M +3X 2  2MX 3 X 2 any halogen, TI  Reactions with ions gives as TIX well,  2M + 6H +  2M 3+ + 3H 2 but no TII 3  2M + 2OH - + 6H 2 O  - + 3H 2 2M(OH) 4  Reactions with O  4M + 3O 2  2M 2 O 3 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts

Group 4A  Electron configuration is ns 2 np 2 (n is the period number).  The half filled orbital allows this group to straddle between metal and non metal.  The heavier elements of the group are more likely to keep their s electrons and can have oxidation numbers of +2 or +4. Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 18

Group 4A Carbon Silicon  Central element to life  Central element to electronic technology  Nonmetallic properties and artificial intelligences.  Forms Covalent bonds  Larger atomic size than C with nonmetals and ionic which results in relatively bonds with metals few compounds that  Small radius allows for the have Si=Si and Si=O wide occurrence of C=C bonds. and C=O bonds in compounds Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 19

Group 4A Tin Germanium Lead  Germanium is  Tin is easily  Lead is durable recovered from obtained from it and malleable the flue dust of ore (cassiterite which makes it industrial plants (SnO 2 )) by useful in the processing zinc reduction with construction ores. carbon. industry  Germanium is  Tin is expensive  It is very dense mainly used in and not very which makes it the strong but it is ideal as semiconductor resistant to radiation shields industry. corrosion. from x rays Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 20

Group 4A Important Compounds  CO 2  CO Red = Silicon  SiO 2 (Silica) Purple = Oxygen  ZnSiO4 (Zircon)  CaMg 5 (Si 4 O 11 ) 2 (OH) 2  Silicones Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 21

Group 4A Common Reactions  Reactions with O  Reaction with Halogens  M + O 2  MO 2  M +2X 2  MX 4 X 2 = any halogen  Reactions with ions molecule,  M + 2H +  M 2+ + H 2 M = Ge or Sn; Pb M = Sn or Pb gives PbX 2 Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 22

Group 5A  Electron configurations ns 2 np 3 (n is the period number)  Oxidation states that range from -3 to +5  The metallic character of the group increases down the group Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 23

Group 5A Nitrogen Phosphorus  Rare in the Earth’s crust  White phosphorus is a soft, but elemental nitrogen white, poisonous, highly (N 2 ) is the principal reactive molecular solid component of our consisting of tetrahedral P 4 atmosphere (76% by molecules. White phosphorus mass) burst into flames when exposed to air.  N ≡ N triple bond strength is 944 𝑙𝐾 𝑛𝑝𝑚 making it almost  Red phosphorus is used in the striking surfaces of matches as inert as the noble because the phosphorus gases. ignites with friction. Chapt pter er 18 18: The Representa esentati tive e Eleme ment nts 24