6.2 Names and Formulas of Chemical Compounds. Part 1. Friday February 28, Tuesday, March 4, 14

Transcription

1 6.2 Names and Formulas of Chemical Compounds Part 1 Friday February 28, 2014.

2 Common Name Chemical Name Chemical Formula vinegar acetic acid CH3COOH table salt sodium chloride NaCl chalk calcium sulphate CaSO4 baking soda sodium hydrogen carbonate NaHCO3

3 each chemical compound has an official chemical name, even though you may know them by the common name the chemical formula identifies the number of each element in the compound for example, baking soda s chemical name is sodium hydrogen carbonate, and its chemical formula is NaHCO 3 (meaning there is one Na, one H, one C and three O s in each molecule of baking soda)

4 the ion notation contains the symbol for the element and a superscript number and + or - sign example: lithium - Li + (remember, ions with a 1+ or 1- charge don t need the 1 ) What is the ion notation of: beryllium? nitrogen? sulphur? Be 2+ N 3- S 2-

5 Element Ion Charge Ion notation hydrogen 1 + H + oxygen 2 - O 2- fluorine 1 - F - magnesium 2 + Mg 2+

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7 RULES (MEMORIZE THESE!): 1.Name the metal ion first: The name of the metal ion is the same as the element name. For example, in NaCl, the name of the sodium ion (Na + ) is sodium. 2.Name the non-metal ion second: When a non-metal becomes a negative ion, the ending of its name changes to -ide. For example, a chlorine atom (Cl) gains an electron to become a chloride ion (Cl - ). 3.Combine these two parts for the complete name: For example the name of NaCl is sodium chloride.

8 Formula Positive Ion Negative Ion Name MgO Mg 2+ O 2- magnesium oxide BaF2 Ba 2+ F - barium fluoride K3N K + N 3- potassium nitride

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11 WRITING IONIC FORMULAS example #1: calcium + chlorine In order to figure out how many of each element you ll need to make a compound, draw the Lewis diagrams (remember last week?!) x x x x xx x Cl Ca x x x Cl xx x x CaCl 2 (calcium chloride)

12 WRITING IONIC FORMULAS example #2: aluminum + oxygen x x x x xx x x O Al O x x x x Al x x O xx x x Al 2 O 3 (aluminum oxide)

13 WRITING IONIC FORMULAS CaCl2 Hmm...notice something? Charge on: Ca 2+ Cl - CRISS CROSS RULE! Why does this work? The charges even out! 1( 2+ ) + 2( 1- ) = 0! formula: Look back at the Ca Cl

14 WRITING IONIC FORMULAS Al2O3 Charge on: Al 3+ O 2- Look back at the CRISS CROSS RULE! 2( 3+ ) + 3( 2- ) = 0! formula: Al O

15 WRITING IONIC FORMULAS example: calcium + chlorine 1. Write the element symbols with the metal ion written first. 2. Take the number of the charge on the non-metal ion and make it a subscript on the metal ion (if it s 1, you can just leave it without a number). 3. Take the number of the charge on the metal ion and make it a subscript on the non-metal ion (if it s 1, you can just leave it without a number). Ca Cl Ca 2+ Cl - Ca Cl CaCl2

16 WRITING IONIC FORMULAS elements ions formula name potassium and iodine K +, I - KI potassium iodide magnesium and chlorine Mg 2+, Cl - MgCl2 magnesium chloride rubidium and phosphorus Rb +, P 3- Rb3P rubidium phosphide beryllium and sulfur Be 2+, F - BeF2 beryllium fluoride aluminum and nitrogen Al 3+, N 3- AlN aluminum nitride When the elements have the same charge value (the number), you can cancel the numbers out...

17 WRITING IONIC FORMULAS example: aluminum + nitrogen Al N x x x x x AlN

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19 elements like iron, copper, and lead can form an ion in more than one way: these are multivalent ions in this case, a Roman numeral is included in the ion s name to show the ion s charge example: the name Fe 2+ is iron (II) which is read iron two. The two refers to the charge. Similarly iron (III) is read iron three and named the Fe 3+ ion.

20 1 I 2 II 3 III 4 IV 5 V 6 VI

21 WRITING IONIC COMPOUND FORMULAS WITH MULTIVALENT IONS example: iron (III) oxide 1. Write the ion for the metal. Fe Write the ion for the non-metal. O 2-3. Use the criss-cross rule to find the formula. Fe2O3 example: chromium (II) chloride lead (IV) nitride CrCl2 Pb3N4

22 NAMING IONIC COMPOUNDS WITH MULTIVALENT IONS example: Cu3N2 1. Look at the subscript number on the non-metal ion. This is the positive charge on the multivalent ion. 2. Name that ion. Specify the charge using Roman numerals. 3. Name the other ion. Add ide to the ending. Cu 2+ copper (II) copper (II) nitride example: FeCl3 CuO iron (III) chloride copper (II) oxide

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24 POLYATOMIC IONS a group of atoms, made of more than one element, that act as a single ion

25 NAMING POLYATOMIC IONS example: NaOH 1. Name the metal. sodium 2. Name the polyatomic ion. DO NOT CHANGE THE NAME. sodium hydroxide HINTS: the polyatomic ion is often in brackets like Al(OH)3 if there is more than one element after the metal, it s probably polyatomic: CuSO4

26 CAUTION: Watch for Polyatomics and Multivalents! names of elements or polyatomic ions ion notation formula chemical name potassium and hydroxide K +, OH - KOH potassium hydroxide copper (II) and nitrogen Cu 2+, N 3- Cu3N2 copper (II) nitride iron (III) and sulphate Fe 3+, SO4 2- Fe2(SO4)3 iron (III) sulphate barium and chlorate Ba 2+, ClO3 - Ba(ClO3)2 barium chlorate lithium and nitrate Li +, NO3 - LiNO3 lithium nitrate

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29 WRITING NAMES FOR MOLECULAR COMPOUNDS 1 = mono 2 = di 3 = tri 4 = tetra 5 = penta 6 = hexa 7 = hepta 8 = octa 9 = nona 10 = deca

30 WRITING NAMES FOR MOLECULAR COMPOUNDS

31 WRITING NAMES FOR MOLECULAR COMPOUNDS

32 WRITING FORMULAS FOR MOLECULAR COMPOUNDS

33 WRITING FORMULAS FOR MOLECULAR COMPOUNDS