Writing Chemical formula with polyatomic groups

Transcription

1 Writing Chemical formula with polyatomic groups 1. Use the Periodic table to determine the combining powers of single elements. Eg. Magnesium is in Group 2 and has a combining power of Use Table 1 to determine the valency of the major polyatomic groups. Table 1: The Combining Power of Polyatomic Ions Combining power of 1 Combining power of 2 Combining power of 3 + Ammonium ion, NH 4 - Hydrogen carbonate ion, HCO 3 Hydroxide ion, OH - - Nitrate ion, NO 3 Carbonate ion, CO 3 2- Sulfate ion, SO 4 2- Phosphate ion, PO 4 3- Chemical Formula Help Rule 1: The charge tells you the combining power. Do not write the charge in the chemical formula! Eg. The chemical formula for magnesium nitrate is Mg(NO 3 ) 2 and not Mg 2+ (NO 3 - ) 2 or Mg(NO 3 - ) 2 Rule 2: Brackets() are needed when a polyatomic group > 1 in a compound. Poly = many The hydroxide ion, formula OH -, is a polyatomic group since it is made up of two different elements. Eg. The chemical formula for strontium hydroxide is Sr(OH) 2 and not SrOH 2 Eg. The formula for lithium hydroxide is LiOH and not Li(OH) since there is only one OH group. Rule 3: Do not use brackets when single elements are > 1 in a formula. Eg. The chemical formula for lithium carbonate is Li 2 CO 3 and not (Li) 2 CO 3 Rule 4. Roman numerals are used for metal valencies that vary. Eg. Iron(II) oxide, FeO If in doubt use a combining power of 2. Eg. Copper sulfate, CuSO 4 and lead chloride, PbCl 2 Rule 5. The valency of silver is always 1. The valency of zinc is always 2.

2 112 Cn Copernicium 9 F Fluorine 17 Cl Chlorine 35 Br Bromine 53 I Iodine 85 At Astatine 7 N Nitrogen 15 P Phosphorus 33 As Arsenic 51 Sb Antimony 83 Bi Bismuth 5 B Boron 13 Al 31 Ga Gallium 49 In Indium 81 Tl Thallium 107 Bh Bohrium 108 Hs Hassium 109 Mt Meitnerium 110 Ds Darmstadtium 111 Rg Roentgenium 87 Fr Francium 88 Ra Radium Actinoids 104 Rf Rutherfordium 105 Db Dubnium 106 Sg Seaborgium 1 H Hydrogen KEY 2 He Helium 3 Li Lithium 4 Be Beryllium Atomic Number Symbol Standard Atomic Weight Name Gold 6 C Carbon 8 O Oxygen 10 Ne Neon 11 Na Sodium 12 Mg Magnesium 14 Si Silicon 16 S Sulfur 18 Ar Argon 19 K Potassium 20 Ca Calcium 21 Sc Scandium 22 Ti Titanium 23 V Vanadium 24 Cr Chromium 25 Mn Manganese 26 Fe Iron 27 Co Cobalt 28 Ni Nickel 29 Cu Copper 30 Zn Zinc 32 Ge Germanium 34 Se Selenium 36 Kr Krypton 37 Rb Rubidium 38 Sr Strontium 39 Y Yttrium 40 Zr Zirconium 41 Nb Niobium 42 Mo Molybdenum 43 Tc Technetium 44 Ru Ruthenium 45 Rh Rhodium 46 Pd Palladium 47 Ag Silver 48 Cd Cadmium 50 Sn Tin 52 Te Tellurium 54 Xe Xenon 55 Cs Caesium 56 Ba Barium Lanthanoids 72 Hf Hafnium 73 Ta Tantalum 74 W Tungsten 75 Re Rhenium 76 Os Osmium 77 Ir Iridium 78 Pt Platinum 79 Au Gold 80 Hg Mercury 82 Pb Lead 84 Po Polonium 86 Rn Radon 79 Au The Combining Power or Valencies of the Transition Metals Vary The Combining Power or Valencies of the Elements of the Periodic Table Aluminium

3 Chemical Formula of Compounds with Polyatomic Groups Sheet 1 A polyatomic group contains more than 1 element. Eg. The hydroxide group, OH - contains oxygen and hydrogen. Polyatomic groups greater than 1 in a formula need brackets. eg. Mg(OH) 2 and not MgOH 2 1 silver nitrate 2 ammonium nitrate 3 zinc sulfate 4 aluminium hydroxide 5 sodium sulfate 6 potassium carbonate 7 magnesium hydroxide 8 calcium carbonate 9 potassium phosphate 10 sodium nitrate 11 potassium hydroxide 12 magnesium phosphate 13 barium hydroxide 14 ammonium sulfate 15 aluminium phosphate 16 sodium hydrogen carbonate 17 barium nitrate 18 iron(ii) hydroxide 19 zinc phosphate 20 aluminium carbonate 21 silver phosphate 22 aluminium sulfate 23 potassium sulfate 24 silver sulfate 25 magnesium nitrate

4 Chemical Formula of Compounds with Polyatomic Groups Sheet 2 A polyatomic group contains more than 1 element. Eg. The hydroxide group, OH - contains oxygen and hydrogen. Polyatomic groups greater than 1 in a formula need brackets. eg. Mg(OH) 2 and not MgOH 2 26 sodium hydroxide 27 barium phosphate 28 calcium sulfate 29 potassium hydrogen carbonate 30 copper nitrate 31 calcium phosphate 32 sodium carbonate 33 lead(ii) sulfate 34 silver hydroxide 35 calcium nitrate 36 calcium hydroxide 37 sodium phosphate 38 ammonium phosphate 39 aluminium nitrate 40 barium sulfate 41 magnesium sulfate 42 iron(ii) sulfate 43 iron(iii) hydroxide 44 lead(ii) nitrate 45 copper sulfate 46 barium carbonate 47 copper hydroxide 48 copper carbonate 49 zinc nitrate 50 potassium nitrate

5 Chemical Formula of Compounds with Polyatomic Groups Sheet 1- ANSWERS 1 silver nitrate AgNO 3 2 ammonium nitrate NH 4 NO 3 3 zinc sulfate ZnSO 4 4 aluminium hydroxide Al(OH) 3 5 sodium sulfate Na 2 SO 4 6 potassium carbonate K 2 CO 3 7 magnesium hydroxide Mg(OH) 2 8 calcium carbonate CaCO 3 9 potassium phosphate K 3 PO 4 10 sodium nitrate NaNO 3 11 potassium hydroxide KOH 12 magnesium phosphate Mg 3 (PO 4 ) 2 13 barium hydroxide Ba(OH) 2 14 ammonium sulfate (NH 4 ) 2 SO 4 15 aluminium phosphate AlPO 4 16 sodium hydrogen carbonate NaHCO 3 17 barium nitrate Ba(NO 3 ) 2 18 iron(ii) hydroxide Fe(OH) 2 19 zinc phosphate Zn 3 (PO 4 ) 2 20 aluminium carbonate Al 2 (CO 3 ) 3 21 silver phosphate Ag 3 PO 4 22 aluminium sulfate Al 2 (SO 4 ) 3 23 potassium sulfate K 2 SO 4 24 silver sulfate Ag 2 SO 4 25 magnesium nitrate Mg(NO 3 ) 2

6 Chemical Formula of Compounds with Polyatomic Groups Sheet 2 - ANSWERS 26 sodium hydroxide NaOH 27 barium phosphate Ba 3 (PO 4 ) 2 28 calcium sulfate CaSO 4 29 potassium hydrogen carbonate KHCO 3 30 copper nitrate Cu(NO 3 ) 2 31 calcium phosphate Ca 3 (PO 4 ) 2 32 sodium carbonate Na 2 CO 3 33 lead(ii) sulfate PbSO 4 34 silver hydroxide AgOH 35 calcium nitrate Ca(NO 3 ) 2 36 calcium hydroxide Ca(OH) 2 37 sodium phosphate Na 3 PO 4 38 ammonium phosphate (NH 4 ) 3 PO 4 39 aluminium nitrate Al(NO 3 ) 3 40 barium sulfate BaSO 4 41 magnesium sulfate MgSO 4 42 iron(ii) sulfate FeSO 4 43 iron(iii) hydroxide Fe(OH) 3 44 lead(ii) nitrate Pb(NO 3 ) 2 45 copper sulfate CuSO 4 46 barium carbonate BaCO 3 47 copper hydroxide Cu(OH) 2 48 copper carbonate CuCO 3 49 zinc nitrate Zn(NO 3 ) 2 50 potassium nitrate KNO 3