ionic and covalent nomenclature
DESCRIPTION
Naming Compounds Writing Formulas. Ionic and Covalent Nomenclature . Systematic Naming. There are more than 50 million named chemical substances Who thinks up the names for all these chemicals? Are we in danger of running out of new names? - PowerPoint PPT PresentationTRANSCRIPT
Inorganic Nomenclature
Naming CompoundsWriting Formulas
Systematic Naming
There are more than 50 million named chemical substances
Many have common names that we use everyday like sugar, table salt, borax, and sand
They all have systematic names that make keep track of them easier and uniquely identify each one.
Compounds
Follow the Law of Definite Proportion.Have a constant composition.Same formula (atoms) every timeTwo Major Types of Compounds
Ionic Covalent or Molecular
Molecular Compounds
Covalent Compounds Made of moleculesMade by joining nonmetal atoms
together into moleculesNon-Metal Non-Metal
Combinations Soft solids, liquids, and gases Carbon dioxide CO2Dihydrogen monoxide H2O
Ionic Compounds
Made of cations and anionsPositive ion bonded to negative ionMetal Non-Metal CombinationsThe electrons lost by the cation are
gained by the anionThe cations and anions surround
each otherSmallest ratio of ions in an ionic
compound is a FORMULA UNIT.All hard, brittle solids Calcium chloride CaCl2
K+1
Ca+2 Has lost two electrons
Cations
Positive ionsFormed by losing electronsMore protons than electronsMetals usually
Has lost one electron
AnionA negative ionHas gained electronsNon metalsCharge is written as a superscript
on the right.
F-1 Has gained one electron
O-2 Has gained two electrons
Chemical Formulas
Shows the kind and number of atoms in the smallest piece/ratio of a substance
CO2 C6H12O6AlBr3
Formula Unit
The smallest whole number ratio of atoms in an ionic compound.
Ions surround each other so you can’t say which is hooked to which
Two systems for naming inorganic compounds The Stock (Roman numeral) System
used for Ionic Compounds
The Numerical Prefix System used for Covalent Compounds
General Rules for Roman # SystemWrite the name of the less
electronegative element or polyatomic ion
Write down the name of the other element or polyatomic ion
Put a Roman numeral in parentheses after the first element name The Roman numeral is equal to the
oxidation state (charge) of the first element
Rules for Binary Compounds Composed of 2 different elements Write down the name of the less
electronegative element (metal) Write down the root of the other
element then add ---ide to the end. Place the roman numeral in
parentheses after the first element if needed Roman # equals the charge of the first
element
Determining Charges on ionsFor Elements in Groups 1, 2,13-18
on the Periodic Table you can tell what kind of ion they will form from their location on the table
Elements in the same group have similar properties
Including the charge when they are ions
+2+1
+3 -3 -2 -1
What about the others?
We have to figure those out some other way.
Naming Ions
We will use the systematic wayCation- if the charge is always the
same just write the name of the metal (Gr. 1, 2, 13)
Transition metals can have more than one type of charge
Indicate the charge with a Roman numeral in parentheses
How we determine this in a bit
Name these
Na+1 Ca+2 Al+3 Fe+3 Fe+2 Pb+2 Li+1
Write Formulas for these
Potassium ionMagnesium ion Copper (II) ionChromium (VI) ionBarium ionMercury (II) ion
Naming Anions
Anions are always the same when it comes to charge
Change the element ending to – ideF-1 fluorideS-2 sulfideP-3 phosphideTe-2 telluride
Name these
Cl-1
N-3
Br-1
O-2
Ga+3
Write these
Sulfide ion iodide ionphosphide ionStrontium ion
Polyatomic ionsGroups of atoms that stay
together and have a chargeYou must memorize these or use
an ion sheetAcetate C2H3O2
-1
Nitrate NO3-1
Nitrite NO2-1
Hydroxide OH-1Permanganate MnO4
-1 Cyanide CN-1
Polyatomic ionsSulfate SO4
-2
Sulfite SO3-2
Carbonate CO3-2
Chromate CrO4-2
Dichromate Cr2O7
-2
Phosphate PO4-3
Phosphite PO3-3
Ammonium NH4
+1
Hints for Naming Polyatomic Ions
Ending Formula
Name (from the element that is not oxygen)
Chlorine Formula
---ide No oxygen
S-2 Sulfide Chloride Cl-1
---ite Some oxygen
SO3-2 Sulfite Chlorite ClO2-1
---ate More oxygen
SO4-2 Sulfate Chlorate ClO3-1
Hypo--- ---ite
Less oxygen
Hypochlorite
ClO-1
Per--- -----ic
Most oxygen
Perchlorate ClO4-1
Naming Ionic Compounds
Binary Ionic Compounds (salts)Binary Compounds
2 elements Metal nonmetal a cation and an anion + -
To write the names just name the two ions.
Groups 1, 2, 13
Easy with Representative elements Groups 1, 2, 13 Charge determined by location in table
NaCl = Na+ Cl- = sodium chlorideMgBr2 = Mg+2 Br- = magnesium
bromide
Naming Binary Ionic Compoundswith Variably Charged Cations
The problem comes with the transition metals and in other variable charged cations
Elements not are not in groups 1, 2 , or 13. Need to figure out their charges.
How?
How do we figure out the roman numeral? The compound must be neutral Same number of + and – charges Look up the charge on the negative Calculate the total negative charge Must be equal to total positive
charge Divide positive total by number of
atoms Result is equal to charge on positive This is the Roman numeral
Example: Determining the Roman Numeral
Write the name of CuOCopper is not in gr 1, 2, or 13 so
need a roman numeral O is -2 thereforeCopper must be +2 so the roman
numeral = 2Name is Copper (II) chloride
Another in Class ExampleName the following:
CoCl3
Another Example Write the name of Cu2S
Last Example
Fe2O3
Naming Binary Ionic Compounds Write the names of the following KCl Na3N CrN Sc3P2 PbO PbO2
Na2Se
Ternary Ionic Compounds Will have at least one polyatomic ions At least three elements Name the ions: Use a roman numeral if needed. NaNO3
CaSO4
CuSO3
(NH4)2O
Ternary Ionic Compounds
LiCN
Fe(OH)3
(NH4)2CO3
NiPO4
Writing Formulas Given the name write the formula
Things to remember: The charges in a compound have to add
up to zero1. Write down each ion with charges2. Make the charges equal by adding
subscripts3. Put polyatomic ions in parentheses
before using a subscript
Writing Formulas ExampleWrite the formula for calcium
chloride.Calcium is Ca+2 Chloride is Cl-1 Charge on compound must be 0. So 2 Cl-1 are needed to make the
charge = to zero.CaCl22 atoms of chlorine for every one atom of calcium
Another Example
Aluminum nitrate
Write the formulas for theseLithium sulfidetin (II) oxidetin (IV) oxideMagnesium fluorideCopper (II) sulfateIron (III) phosphide
Write the formulas for thesegallium nitrate Iron (III) sulfide
Ammonium chloride
ammonium sulfide
barium nitrate
Things to look for
If cation has a (Roman Numeral), the number is the charge of the positive ion
If anions end in -ide they are probably off the periodic table (monoatomic) but can be cyanide, hydroxide
If anion ends in -ate or -ite it is polyatomic
Molecular CompoundsWriting names and Formulas
Molecular compounds
Nonmetal Nonmetal combinationssmallest piece is a moleculeAlso called covalent compoundsnot held together because of
opposite charges
Easier
Molecular compounds name tells you the number of atoms
Uses prefixes to tell you the number
Prefixes
1 mono-2 di-3 tri-4 tetra-5 penta-6 hexa-7 hepta-8 octa-
Prefixes
9 nona-10 deca-
Prefixes
9 nona-10 deca-To write the name write two words
Prefix name Prefix name -ide
Prefixes
9 nona-10 deca-To write the name write two words
One exception is we don’t write mono- if there is only one of the first element.
Prefix name Prefix name -ide
Prefixes9 nona-10 deca-To write the name write two words
One exception is we don’t write mono- if there is only one of the first element.
No double vowels when writing names (oa oo) except with i
Prefix name Prefix name -ide
Name These
N2O
NO2
Cl2O7
CBr4
CO2
BaCl2
Write formulas for these
diphosphorus pentoxide tetraiodide nonoxide sulfur hexaflouride nitrogen trioxide carbon tetrahydride phosphorus trifluoride aluminum chloride
AcidsWriting names and Formulas
Acids
Compounds that give off hydrogen ions when dissolved in water.
Must have H in themwill always be some H next to an
anionHClH2SO4The anion determines the name
Anions/AcidsAnion Example Acid Example
….ide Cl- 1
chloride Hydro…ic HCl
Hydrochloric acid
…..ite ClO2- 1
chlorite ….ous HClO2
Chlorous acid
Hypo…..ite ClO-1
hypochloriteHypo….ous HClO
Hypochlorous acid
…..ate ClO3- 1
chlorate ….ic HClO3
Chloric acid
Per…ate ClO4- 1
perchlorate Per……ic HClO4
Perchloric acid
Naming acids: Three Rules Rule 1: If the anion attached to
hydrogen is ends in -ide, put the prefix hydro- and change -ide to -ic acid Example: HCl - hydrogen ion and
chloride ion
Example: H2S hydrogen ion and sulfide ion
Naming OxyAcids
If the anion has oxygen in it it ends in -ate of -ite
Rule 2: change the suffix -ate to -ic acid
Example: HNO3 Hydrogen and nitrate ions
Rule 3: change the suffix -ite to -ous acid Example: HNO2 Hydrogen and nitrite
ions
Name these
HFH3PH2SO4 H2SO3 HCNH2CrO4
Writing Formulas
Hydrogen will always be firstname will tell you the anionmake the charges cancel out.Rule 1: hydro- no oxygen, -ide
ion
Rule 2 : no hydro, -ate comes from -ic,
Rule 3: no hydro -ite comes from -ous
Write formulas for these
hydroiodic acid
acetic acid
carbonic acid
phosphorous acid
hydrobromic acid
Hydrates
A solid compound with a specific number of water molecules bonded to it
Release water when heated at fairly low temperatures
Anhydrous Solid•xH2O) Common Example: CuSO4 5H2OCopper (II) sulfate pentahydrateThe penta indicates five water
molecules for each copper (II) sulphate particle
Prefixes
The prefix indicates the number of water molecules bonded to the anhydrous salt
Name to Formula
zinc sulphate heptahydrate copper (I) sulphite monohydrate cobalt (II) fluoride tetrahydrate lithium nitrate trihydrate sodium sulphate decahydrate calcium nitrate trihydrate
Formula to Name
Na2SO4 10H2O LiNO3 3H20 Cu2SO3 3H20 Ca(N03) 2 2H20 MgS04 7H20 ZnS04 7 H20