naming compounds
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Naming Compounds. What's in a name? That which we call a rose By any other name would smell as sweet." - William Shakespeare, Romeo and Juliet (II, ii). BACKGROUND:. - PowerPoint PPT PresentationTRANSCRIPT
Naming CompoundsNaming Compounds
What's in a name? That which we call a roseBy any other name would smell as sweet."
- William Shakespeare, Romeo and Juliet (II, ii)
Prior to the 1700s, there was no systematic method of naming compounds. Substances were named in variety of ways, such as the use of compounds, the property of the compound, or the source of the substance. These names give little, if any, information about the composition of the compound.
Common Name: Quick lime/ Lime
IUPAC Name: Calcium Oxide
Chemical Formula: CaO
Use or property: Neutralizing acidified lakes
Common Name: Baking Soda
IUPAC Name: Sodium bicarbonate
Chemical Formula: NaHCO3
Use or property: Making baked goods rise
Common Name: Laughing gas
IUPAC Name: Dinitrogen monoxide
Chemical Formula: N2O
Use or property: Used in dentistry as
anaesthetic
Common Name: Table salt
IUPAC Name: Sodium Chloride
Chemical Formula: NaCl
Use or property: Enhancing flavour
Common Name: Quartz sand
IUPAC Name: Silicon dioxide
Chemical Formula: SiO2
Use or property: manufacturing glass
• Valence electrons are the number of electrons in the outer energy level of an atom.
• “Valence” describes the number of electrons gained, lost or shared to achieve stability.
• For first 20 elements valence starts at 1 (alkali metals), climbs to 4 (group 4) and falls back to 1 (halogens)
• By knowing the valence of elements you can determine the formula of compounds
• E.g. what compound would form from C + S?Step 1 - write valences:
Step 2 – balance valences by adding atoms: Step 3 – write # of each atom as a subscript
Background: valences and formulas
C S4 2
C S4 2 2
CS2
a) Al,Br b) K,S c) Zn,O d) Mg,N e) C,Cl f) Na,O
AlBr3 K2S ZnO Mg3N2 CCl4 Na2O
Al Br
3 1
1
1
AlBr3
K S
1 2
1
K2S
Zn O
2 2
ZnO
Mg N
2 3
2 3
2
Mg3N2
C Cl
4 1
1
1
1
CCl4
Na O
1 2
1
Na2O
Ionic compoundsRules for naming
• Names end in -ide. Example: sodium chloride• 1. Write metal name first then non metal• 2. Change the ending of the non metal to “ide”• 3. Do not capitalized unless starting a
sentence
Give formulae & name: Ca + I, O + Mg, Na + S= Ca2I1 = CaI2 = calcium iodide= Mg2O2 = MgO = magnesium oxide= Na1S2 = Na2S = sodium sulfide
Multiple Valence
• Some metals have more than one valence.
• For these metals, you can use the Latin or IUPAC method
• Latin is older (not useful for some compounds)
• IUPAC is more commonly used
Latin naming• As before, the metal name if written first and
the non metal ends in -ide• The metal is named with it’s Latin or English
root and ends in “–ic” or “–ous” to denote valence
• E.g. Cu1 is cuprous, E.g. Cu2 is cupric• Lower = ous, Higher = ic• Give formulas and Latin names for:
Cu2 + Cl = Cu2Cl1 = CuCl2 = cupric chlorideCu1 + Cl = Cu1Cl1 = CuCl = cuprous chloride
Element (valence)
English name
Latin Name Higher valence
Lower valence
Metals that have and use latin names Cu (1,2) Copper Cuprum Cupric Cuprous Fe (2,3) Iron Ferrum Ferric Ferrous Pb (2,4) Lead Plumbum Plumbic Plumbous Sn (2,4) Tin Stannum Stannic Stannous
Metals that do not have latin names Co (2,3) Cobalt - Cobaltic Cobaltous Cr (2,3) Chromium - Chromic Chromous Mn (2,3) Manganese - Manganic Manganous
Metals that have latin names but use english root Hg (1,2) Mercury Hydrargyrum Mercuric Mercurous
High with the “i” Low with the “o”
Name the following:
• FeCl2
– Fe -> +2
– Cl -> -1
• CuO– Cu -> +2
– O -> -2
–Ferrous chloride - Cupric oxide
• Metal comes first, ending of non metal is “ide”• The valence of the metal is indicated in
brackets using roman numerals• E.g. Cu1 is copper(I), Cu2 is copper(II)• Numbers refer to valences not to #s of atoms• Try: Cu2+Cl, Zn2 + Cl, Co2+Cl, Hg+S (do both)
Cu2+Cl = Cu2Cl1 = CuCl2 = copper(II) chlorideZn2+Cl = Zn2Cl1 = ZnCl2 = zinc chlorideCo2+Cl = Co2Cl1 = CoCl2 = cobalt(II) chlorideHg+S = Hg1S2 = Hg2S = mercury(I) sulfideHg+S = Hg2S2 = HgS = mercury(II) sulfide
IUPAC naming
• Groups of atoms can also have valences• “Polyatomic ions” are groups of atoms that interact as
a single unit. • E.g. OH1, (SO4)2. Ba3(PO4)2 =
Compounds containing polyatomic ions• So far we have given valences to single atoms
Li + O Li1O2 Li2O
barium phosphate
• Naming compounds with polyatomic ions is similar to naming other ionic compounds
• Put the metal name first, then the name of the polyatomic second.
• You should note that compounds with polyatomic ions have names ending in -ate or -ite not -ide
• Name: Ca(OH)2, CuSO4, NH4NO3, Co2(CO3)3
- calcium hydroxide
- copper(II) sulfate
- ammonium nitrate
- cobalt(III) carbonate
Ca(OH)2
CuSO4
NH4NO3
Co2(CO3)3
Compounds containing polyatomic ions
Naming covalent compounds• -ide ending, each element has “prefix”1 mono
2 di
3 tri
4 tetra
5 penta
6 hexa
7 hepta
8 octa
9 nona
10 deca
• prefix refers to # of atoms - not valenceN2O4 = dinitrogen tetroxide
• Exception: drop mono for first elementCO2 = carbon dioxide
• The first vowel is often dropped to avoid the combination of “ao” or “oo”.
CO = carbon monoxide
(monooxide)SO2= sulfur dioxide (doxide)
• Name: CCl4, P2O3, IF7
P4O10= tetraphosphorus decoxide
Write and name the following covalent compounds (IUPAC)
carbon tetrachloride
diphosporus trioxide
iodine heptafluoride
CCl4
P2O3
IF7
Write the formulas for the following covalent compounds
(IUPAC)
dicarbon tetrasulfide
pentaphosphous dioxide
iodine octafluoride
C2Cl4
P5O2
IF8