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Naming Compounds
Names and Formulas
Writing Chemical Formulas
Chemical Formula:Chemical Formula: 1 – what elements 2 - ratios in compound
Metals(positive ions) written first Polyatomic Ions:Polyatomic Ions:
group of atoms that act as an element has its own ionic charge Always look on the Data Table for
name and ion charge
Ion Charge and the Formulas of Ionic
Compounds Law of Definite Proportions:Law of Definite Proportions:
a specific compound elements are always in definite proportions; integers no decimals or fractions
Ex: H2O – always 2 hydrogen atoms for one oxygen atom
Ionic compounds:Ionic compounds: metal + non-metal Electron(s) transferred bonded by electrical force (opp. charges
attract) electrically neutral
Ion Charge and the Formulas of Ionic
Compounds Ionic compounds:Ionic compounds:
metal + non-metal Positive ion + negative Cation + Anion
Formulas of Ionic Compounds
Use Cross-over Rule:
Ion Charge and the Formulas of Ionic
Compounds Formulas for Ionic Compounds with
Polyatomic Ions: Use crossover rule but
Polyatomic Ions --- MUST BE KEPT TOGETHER
Use brackets around polyatomic groups if there is more than 1
Ion Charge and the Formulas of Ionic
Compounds multivalent:multivalent:
element with more than 1 possible ion charge; occurs only after atomic # 20 – Ca Are in Transition metals on PT
Use crossover rule When naming the CHARGE is written in
roman numerals ex. Iron(III)(III)oxide
Naming Ionic Compounds
Rules for Naming Ionic Compounds: Metal(pos) ion written 1st name spelled same in lower case non-metal ion written 2nd given suffix “–ide”“–ide”
Naming Ionic Compounds
Naming Polyatomic Ions:Naming Polyatomic Ions: pos. polyatomic ions written 1st neg. polyatomic ions written 2nd; name of ion
not changed Use the data table
Do Exercise #4
Naming Ionic compounds using the formulaNaming Ionic compounds using the formula
Example 1: Example 1: AgAg22SOSO44 Silver is monovalent, so, no Roman Num. necessarySilver is monovalent, so, no Roman Num. necessary Look up SOLook up SO44 on table – sulphate on table – sulphate Therefore, name is Therefore, name is Silver sulphateSilver sulphate
Example 2: Example 2: CuCu22OO look at the total amt of charge on each half of formula:
The neg side O for oxygen is monovalent – has charge of 2- Therefore the pos side must have a charge of 2+ As there are 2 Cu, the charge on each Cu must be 1+
(1+ plus 1+ equals 2+) Therefore the name of the compound must be
Copper(I) oxide (remember multivalents must use Roman Numerals in the name)
Naming Ionic compounds using the Naming Ionic compounds using the formulaformula
Example 3: Example 3: FeSFeS Iron(Fe) is multivalent, so, Roman Num. necessaryIron(Fe) is multivalent, so, Roman Num. necessary Look up S on Periodic table – has a 2- chargeLook up S on Periodic table – has a 2- charge So, Fe must have a 2+ charge to balanceSo, Fe must have a 2+ charge to balance Therefore the name is Therefore the name is Iron(II) sulphideIron(II) sulphide
Example 4: Example 4: FeFe22(HPO(HPO44))33 look at the total amt of charge on each half of formula:
The neg side: eacg HPO4 has charge of 2- There are 3 HPO4 the neg side must have a charge of 6- (3 x 2- = 6-) As there are 2 Fe, the charge on each Fe must be 3+
(3+ plus 3+ equals 6+) Therefore the name of the compound must be
Iron(III) monohydrogen phosphate (remember multivalents must use Roman Numerals in the name)
Naming Ionic compounds using the formulaNaming Ionic compounds using the formula
Try It: 1 – Ag3PO4
2 – Al2(SO4)3
3 – Fe2S3
4 – CuCl 5 – (NH4)2CO3
6 – VCl3 7 – Hg2CO3
8 – CuSO4
9 – (NH4)2S
Answers: 1 – Silver phosphate 2 – Aluminum sulphate 3 – Iron(III) sulphide 4 – Copper(I) chloride 5 – Ammonium carbonate 6 – Vanadium(III) chloride 7 – Mercury(I) carbonate 8 – copper(II) sulphate 9 – Ammonium sulphide
Naming Ionic compounds using the formulaNaming Ionic compounds using the formula
Do Exercise #5 Do Handout: Writing formulas Quiz
(exercise in Names -> Formulas)
Do Handout: Formula Writing (exercise in Names -> Formulas)
Do Handout: Inorganic Nomenclature Test (may do as Test or Quiz)
Naming Ionic compounds using the formulaNaming Ionic compounds using the formulaHydratesHydrates
When a crystal of an ionic compound is grown by evaporation from aqueous solution, frequently it is found that the crystal structure will include water molecules
Molecules which include water molecules are called HYDRATES
Use prefixes to tell how many water molecules are attached;
Naming Ionic compounds using the Naming Ionic compounds using the formulaformula
Prefixes forPrefixes for HydratesHydrates 1 2 3 4 5 6 7 8 9 10
mono di tri
tetra penta hexa
hepta octa
nona deca
Naming Ionic compounds using the Naming Ionic compounds using the formulaformula
Prefixes forPrefixes for HydratesHydrates
Copper(II)sulphate pentahydrate
Zinc acetate dihydrate
Calcium nitrate tetrahydrate
Examples:
CuSO4*5H2O
Zn(CH3COO)2*2H2O
Ca(NO3)2*4H2O
Do exercise #6 & #7
Naming Covalent Compounds
Unlike Ionic compounds there are several various combinations of elements possible. Ionic example: sodium and chlorine always forms NaCl It is the ONLY possible combination This combination is called a formula unit; NOT
a molecule Covalent example: carbon and oxygen
Naming Covalent Compounds
Unlike Ionic compounds, Covalent compounds has numerous possibilities in how the elements can combine: Example: carbon and oxygen Can form CO or CO2 or CO3
Each has unique properties: CO will kill you while CO2 will not You cannot all these variations carbon oxide A different naming system is necessary
Naming Covalent Compounds
Prefix naming system – use prefixes to name the various covalent molecules
Note: these are molecules not formula units as with Ionic compounds
Examples of naming covalent molecules: carbon and oxygen can form CO or CO2 or CO3 CO is named carbon monoxide CO2 is named carbon dioxide CO3 has a special name carbonate – a polyatomic
structure
Naming Covalent Compounds
Prefixes indicates the number of the types of atoms in a molecule
monoditri
tetrapentahexa
heptaocta
nonadeca
12345678910
Naming Covalent Compounds
Rules for prefixes: 1 - don’t use mono for the first element if there is only one; 2 - always use mono for second element if there is only one atom in the molecule 3 - mono drops the 2nd “o” as in carbon monoxide 4 - second element ends with ‘ide’ 5 – add the appropriate prefix according to number of atoms present in molecule
Naming Covalent Compounds
The name of the molecule always reflects the structure of the molecule Example: P4O10 --- tetraphosphorus decaoxide
You can tell what the formula is by looking at the name;
or
You can tell what the name is by looking at the formula
This makes covalent compounds easy to name and easy to write the formula
Naming Covalent Compounds
REMEMBER: always determine to see if the compound is IONIC orCOVALENT Then follow the appropriate rules Do Exercise #8 & 9
Handout:Nomenclature
Flow Chart
Naming Acids
1 -- has NO oxygen name begins with ‘hydro’ ends with ‘ic’
examples: HF – hydrogen fluoride HCl – hydrogen chloride
2 types of acids:
hydrofluoric acid
hydrochloric acid
Naming Acids
examples: Formula Chemical Name: H2SO3 – hydrogen sulphite H2CO3 – hydrogen carbonate
sulphurous acid
carbonic acid
2 -- has oxygen There are 2 types of acids WITH oxygen:
One type the chemical name ends with “ite” as in hydrogen sulphite The other the chemical name ends with ”ate” as in hydrogen carbonate
for both there is NO ‘hydro’ in the name “ite” becomes ous ”ate” becomes ic
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