Chemical Names & Formulas. Water Ammonia Methane 1

Transcription

1 Chemical Names & Formulas Water Ammonia Methane 1

2 Why Systematic Names? # atomic particles 3 (p, n, e) # elements ~120 # elements in 8 earth s crust (99%) # elements in all 25 living things # compounds >14,000,000 2

3 Why Systematic Names? Water Lime Lye H 2 O CaO NaOH Potash K 2 CO 3 Table Salt NaCl Laughing Gas N 2 O Baking Soda NaHCO 3 3

4 Atoms vs. Ions Atom: neutral no net charge (# p + = # e - ) e.g. Na 11 p + and 11 e - Cl 17 p + and 17 e - 4

5 Atoms and Ions Ion: atom (or group of atoms) has + or charge has more or less e - e - only the # of e - change e - e - e - e - e.g. Na + 11 p + and 10 e - Cl - 17 p + and 18 e - 5

6 Atoms and Ions Na vs. Na + and Cl vs. Cl - Very different Demo: Fe vs. Fe +3 6

7 Ions Positive charge: cation Na + Ca 2+ Al 3+ These atoms lost electrons to become positive ions Negative charge: anion Cl - O 2 - SO 4 2- These atoms gained electrons to become negative ions. 7

8 Atoms vs. Ions free element lose electrons cation + atom gain electrons anion - smaller larger 8

9 Compounds Substances composed of 2 or more different atoms HCl NaCl CO 2 9

10 Chemical Formulas Shows the kinds and numbers of each type of atom in a chemical compound. Water = H 2 O two atoms of H one atom of O 10

11 Compounds Molecular Atoms bonded as a unit nonmetals e.g. H O 2 Ionic Ions held together by + and - charges metal + nonmetal e.g. NaCl Charges NOT shown 11

12 Molecular & Ionic Compounds 12

13 1. Molecular Formulas Discrete units of bonded nonmetal atoms. e.g H O & CO 2 2 O covalent bond H H structural formula for water 13

14 Naming Molecular Compounds (bonded nonmetal atoms) prefix-1 st atom-prefix-2 nd atom-ide number N 2 O 5 = dinitrogen pentoxide 14

15 Number Prefix 1 Mono 2 Di 3 Tri 4 Tetra 5 Penta 6 Hexa 7 Hepta 8 Octa 9 Nona 10 Deca Note: don t use mono for the first atom. 15

16 Try It CO 2 N 2 O PCl 3 SF 6 SO 3 N 2 O 4 H 2 O Dangerous chemical 16

17 Ionic Formulas Ionic compound is represented by a formula unit, the lowest ratio of atoms in the compound. NaCl ionic bond Na + and Cl - 17

18 Naming Ionic Compounds (positive metal ion + negative nonmetal ion) First must learn ion names and charges! 18

19 Monatomic Ions (single atom ions) Metals form cations (+) Mg loses two e - to form Mg +2 Nonmetals form anions (-) The name ends in ide Cl gains one e - to form Cl - Charge from Periodic Table 19

20 Common Monatomic Ions Li + Be 2+ N 3- O 2- F - Na + Mg 2+ Al 3+ P 3- S 2- Cl - K + Ca 2+ As 3- Se 2- Br - Rb + Ba 2+ I - end in --ide 20

21 Monatomic Ions: Try It. When the following elements become ions, state: ion name charge number of e - lost or gained Ca P K S Br Al 21

22 Monatomic Ions: Some metals can form two different types of ions. Iron: Fe +2 and Fe +3 Copper: Cu +1 and Cu +2 See Periodic Table for charges. 22

23 Multiple Charges: Names Stock System: atom (charge) Fe 2+ is Iron(II) ion Fe 3+ is Iron(III) ion 23

24 Multiple Charges: Names Classical System: Latin name ending in ous for lower charge ic for the higher charge Fe 2+ is Ferrous ion Fe 3+ is Ferric ion 24

25 Others Ion Stock Classic Cu + Copper(I) Cuprous Cu 2+ Copper(II) Cupric Pb 2+ Lead(II) Plumbous Pb 4+ Lead(IV) Plumbic Sn 2+ Tin(II) Stannous Sn 4+ Tin(IV) Stannic 25

26 Polyatomic Ions Some atoms group together as a unit to form an ion. - - NO 3 26

27 Polyatomic Ion: Charged group of atoms acting as a unit NO 3 - PO 4 3- SO 4 2- nitrate ion phosphate ion NH 4 + sulfate ion ammonium ion 27

28 Regents Table E Note ite & ate pairs --ite --ate sulfite: SO 3 2- sulfate: SO 4 2- nitrite: NO 2 - nitrate: NO 3 - chlorite: ClO 2 - chlorate: ClO 3 - Be able to recognize them!!! 28

29 Polyatomic Ions Be careful to distinguish between superscripts (charges) and subscripts (number of atoms). sulfite: SO 3 2- is (SO 3 ) 2-1 S & 3 O -2 charge 29

30 Ionic Formulas Name: cation then anion name Potassium chloride K + Cl - KCl Charges must balance But don t write charges! 30

31 Ionic Formulas Calcium bromide Ca 2+ Br - CaBr 2 (balance charge) Copper(I) sulfate Cu + SO 4 2- Cu 2 SO 4 31

32 Shortcut Criss Cross Copper(I) sulfate Cu + SO 4 2- Cu 2 (SO 4 ) 1 = Cu 2 SO 4 The charge number (not sign) of one ion becomes the subscript of the opposite ion. 32

33 Shortcut Criss Cross Calcium sulfide Ca 2+ S 2- Ca 2 S 2 = CaS (reduce) 33

34 Shortcut Criss Cross Iron(III) Carbonate Fe 3+ CO 3 2- (brackets needed Fe 2 (CO 3 ) 3 for polyatomic ion with subscript) 34

35 Name or Give the Formula of That Compound!!! Silver chloride CuBr 2 Ammonium bromide Mg 3 (PO 4 ) 2 Calcium chromate 35

36 Ionic Compounds Cation (+) and Anion (-) Cation (+): usually metal ion Monatomic: use PT, e.g Mg 2+ If more than one charge, use Roman numerials, e.g. iron (II) Polyatomic: use Table E, e.g. NH

37 Ionic Compounds Cation (+) and Anion (-) Anion (-): usually nonmetal ion Monatomic: use top charge on PT, e.g Br -, name ends in ide. Polyatomic: use Table E, most end in ite or ate e.g. NO 3 - Name: cation then anion, no prefix Mg(NO 3 ) 2 is magnesium nitrate 37

38 Ionic Compounds Cation (+) and Anion (-) To write formula, criss-cross: Iron(III) Carbonate Fe 3+ CO 2-3 Fe 2 (CO 3 ) 3 38

39 Try Some More!! N 2 O 5 PCl 3 AlCl 3 Sodium hydrogen sulfate SnO 2 39

40 General Properties Molecular Compounds Weak intermolecular forces (molecular attractions) Low melting & boiling points Ionic Compounds Strong ionic attractions High melting & boiling points 40

41 Naming Acids Acids are a special class of compounds with H + as the cation. Example: H + with Cl - HCl(aq) where (aq) = dissolved in water 41

42 Naming Acids Acids are named according to the anion. 1. If the anion ends in ide, the acid is hydro----ic acid. Cl - is chloride HCl(aq) is hydrochloric acid 42

43 Naming Acids 2. If the anion ends in ite, the acid is ----ous acid. SO 3 2- is sulfite H 2 SO 3 (aq) is sulfurous acid 43

44 Naming Acids 3. If the anion ends in ate, the acid is ic acid. NO 3 - is nitrate HNO 3 (aq) is nitric acid 44

45 Naming Acids: Try It Name HCN(aq) HClO (aq) 4 HClO(aq) HCl(aq) 45

46 Naming Acids: Try It Write the formula for: carbonic acid nitrous acid Regents Table K 46

47 47

48 Summary: Names & Formulas Atoms vs. ions Na Na + Compounds: -molecular (nonmetals) -ionic (metal + nonmetal) cation(+) anion(-) 48

49 Summary: Names & Formulas Molecular compound: -prefix-atom-prefix-atom-ide N 2 O 5 = dinitrogen pentoxide 49

50 Summary: Ionic compounds -know names & charges monatomic ions (PeriodicTable) transition metals -stock system: iron(ii) polyatomic ions: NO 3 - compound name: cation+anion 50

51 51

52 Warm-up How many p + and e - in Ca and Ca +2? Is Ca +2 and anion or cation? What are the two general types of compounds? How do you recognize each? 52

53 Warm-up Name N 2 F 4 and NO 2 53

54 Warm-up Give the symbol and the name of the ion that each element forms: Al P Write the formula of the carbonate ion. How do you know NH 4 NO 3 is ionic even though it has only nonmetal atoms? 54

55 Warm-up 1. Fill in the table: Molecular Types of atoms Name of formula Name of bond Ionic 2. Name N 2 O and Al 2 (SO 4 ) 3. 55

56 Name or give formula: gold(i) sulfate S 2 Cl 5 barium phosphide Fe 3 (PO 4 ) 2 calcium hydrogen carbonate 56

57 Warm-up Write the formula unit for sodium sulfate. Why can t this formula be reduced? 57

58 Is it an ion, molecule, ionic compound, or acid? Then name or give formula: NH 4 + S -2 SO -2 3 magnesium nitride calcium carbonate aluminum hydrogen sulfate NaCN H 2 C 2 O 4 (or Reg. H 2 CO 3 ) SnO FeC 2 O 4 PBr 3 N 2 O SO 3 Au 2 SO 4 58

59 Warm-up Name or write formula: H 2 SO 3 Hydroiodic acid N 2 S 4 FeSO 3 59

60 Warm-up Name or write formula: lead(iv) carbonate barium nitride CO SnS 2 sulfurous acid 60