chapter 9 chemical names and formulas
DESCRIPTION
Chapter 9 chemical names and formulas. Calcium Carbonate. Potassium Sulfate. Hydrogen Phosphate. Carbon Dioxide. Strontium Sulfate. Dinitrogen Monoxide. Naming Ions. Monatomic Ions. Single atom with a positive or negative charge. i. Cation. 1. Lose electrons. 2. Positive charge. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 9 chemical names and formulas
Calcium Carbonate
Carbon Dioxide
Dinitrogen MonoxideStrontium Sulfate
Hydrogen Phosphate
Potassium Sulfate
Naming IonsMonatomic Ions
Single atom with a positive or negative charge
i. Cation1. Lose electrons
2. Positive charge
3. Name remains the sameNa is SodiumNa+ is Sodium cation
ii. Anion
1. Gain electrons
2. Negative charge3. Name starts with the stem and ends in -ide
N is Nitrogen
N3- is Nitride
iii. Transition Metals
1. Lose electrons - cations
2. Positive charge
4. Two ways to name them
3. Transition metals may lose a different number of electrons creating ions with a different charge
a. Stock system-most common way of namingi. A roman numeral is
placed next (with no spaces) to the name of the element indicating the charge
Fe2+ is Iron(II) ion
Fe3+ is Iron(III) ion
Co2+ is Cobalt(II) ionCo3+ is Cobalt(III) ion
b. Classic system-older, less useful way
i. Root word with –ous at the end of the ion with the smaller charge and –ic at the end of the ion with the larger charge
Fe2+ is Ferrous ion
Fe3+ is Ferric ion
Co2+ is Cobaltous ionCo3+ is Cobaltic ion
**There are special metals that change their charge – Tin (Sn) and Lead (Pb)
FYI – many of these transition metal cations are colored and are used as pigments which are used to make different colored paints
Polyatomic IonsIons composed of more than one atom
i. Most that end in -ite or -ate contain Oxygen
iii. The names need to be memorized
ii. If the formula begins with H then the name usually begins with Hydrogen
Naming Ionic CompoundsCompound Names
i. Names of compounds used to be determined by the person who discovered it and the name related to the compounds property or what it was used for
NaHCO3 baking soda – used to bake cakesCaSO4 + ½H2O plaster of Paris – used to make plaster faces
Make it easier to identify names
ii. As more compounds were discovered, it became harder to memorize all the unrelated names.
iii. Antione Lavoisier worked with other chemists to devise a naming system
Binary Ionic Compoundsi. Binary CompoundsIonic or molecular compounds
composed of two elements
ii. Binary Ionic Compounds
Ionic compound composed of a cation and an anion
Naming Binary Ionic Compoundsi. Name the cation first
ii. Name the anion second
Examples: Catio
nAnion Ionic
CompoundCs2O Cesium
Oxide Cesium Oxide
NaCl Sodium
Chloride
Sodium ChlorideSrF2 Strontiu
m Fluoride Strontium
FluorideSnF2
SnS2
Remember Tin is a special metal and needs roman numerals
* *
Cation
Anion Ionic Compound
SnF2 Tin(II) Fluoride Tin(II) Fluoride
SnS2 Tin(IV) Sulfide Tin(IV) Sulfide
Writing Formulas for Binary Ionic Compounds
ii. Write the symbol of the cation and charge
i. If you know the name of the Ionic Compound you can write the formula
iii. Write the symbol of the anion and charge
iv. Add the required subscripts (the positive and negative charges must balance
Examples: Catio
nAnion Ionic
CompoundPotassium Chloride
K+ Cl- KCl
Calcium Bromide Ca2+ Br- CaBr2
Iron(III) Oxide Fe3+ O2- Fe2O3
Naming compounds with polyatomic ions
i. Name the cationsii. Name the polyatomic anionExamples:
Cation
Polyatomic ion Compound
CaCO3
Calcium
Carbonate
Calcium Carbonate
K2HPO4 Potassium
Hydrogen Phosphate
Potassium Hydrogen Phosphate
K2SO4 Potassium
Sulfate Potassium Sulfate
Writing formulas for compounds with polyatomic ions
i. If you know the name of a compound you can write the formula
ii. Write the symbol of the cation and the charge
iii. Write the symbol of the polyatomic anion and the charge
iv. Add the required subscripts (positive and negative charges must balance)
Examples:
Cation
Polyatomic ionCompoundCalcium
Nitrate Ca2
+
NO3- Ca(NO3)
2
Strontium Sulfate
Sr2+ SO42- SrSO4
Naming Molecular CompoundsBinary Molecular compounds
Two elements covalently bonded
Naming Binary Molecular compoundsi. A prefix is added to an element
to state how many of each atom is present (prefix is always added to the second element and only added to the first if the number is greater than one)
Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca
1 2 3 4 5 6 7 8 9 10
Examples:
ii. -ide is added to the end of the second molecule
CO Carbon
Monoxide
CO2
Dinitrogen
Dioxide
N2O
Carbon
Monoxide
Cl2O8 Dichlorine
Octoxide
Writing formulas for Molecular Compounds
i. Write the symbol for the first nonmetal
ii. Write the symbol for the second nonmetal
iii. Use the prefixes to tell you the subscripts
Examples:First Second Formula
Silicon Monocarbide
Si C SiC
Phosphorus pentachloride P Cl5 PCl5
Chlorine trifluoride
Cl F3 ClF3
Dinitrogen tetroxide
N2 O4N2O4
AcidsAcids
- Group of ionic compounds that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water.
Naming Acids
1. When anion ends in –ide the acid name begins with the prefix hydro-, the stem of the anion with the suffix –ic followed by acid
Three Rules
Example:
HCl
* Anion is Chloride
* Name begins with hydro
hydro
* Then the stem of the anion -chlor
chlor
* Then the suffix -ic
ic
* Followed by Acid
acid
2. When anion ends in –ite, the acid name is the stem of the anion with the suffix –ous followed by the word acidExample:
H2SO3
* Anion is Sulfite (pg 257)* Name begins with stem of anion Sulfur
sulfur
* Then the suffix -ous
ous
* Followed by Acid
acid
3. When anion ends in –ate, the acid name is the stem of the anion with the suffix –ic followed by the word acidExample:
HNO3
* Anion is Nitrate (pg 257)
* Name begins with stem of anion Nitr
nitr
* Then the suffix -ic
ic
* Followed by Acid
acid
Writing formulas for Acids
i. The general formula for acids is HnX
where X is the monatomic or polyatomic anion and n is a subscript for the number of hydrogen atoms needed to make the compound neutral
ii. Use the three rules for naming acids in reverse and then balance
Example:
Hydrobromic acid
* Hydro and -ic --- anion ends in -ide
Br-
* Followed by Acid --- Formula is HnX
H+
* Balance
HBr
Phosphorous acid
* Followed by Acid --- Formula is HnX
H+
* -ous --- anion ends in –ite (pg 257)
PO33-
* Balance
H3PO3
Sulfuric acid
* Followed by Acid --- Formula is HnX
H+
* -ic --- anion ends in –ate (pg 257)
SO42-
* Balance
H2SO4
Names and formulas for Basesbases
- Ionic compound that produces hydroxide ion (OH-) when dissolved in water
Naming
i. Name the cation
ii. Name the anion (hydroxide)
Examples:
NaOH
* Name the cation - Sodium
* Name the anion - HydroxideSodium Hydroxide
Al(OH)3
Aluminum Hydroxide
Writing formulas for bases
i. Write the symbol for the cation and charge
ii. Write the symbol for the anion and charge (OH-)
iii. Balance the formula (positive and negative charges must balance)
Examples:
Potassium hydroxide
* Anion and charge – OH-
* Cation and charge – K+
K+ OH-
KOH
* Balance
Laws governing Formulas and Names
Naming using these methods is possible because elements form compounds in
predictable ways
Laws of Definite Proportions
In samples of any chemical compound, the masses of the elements are always in the same proportions because atoms combine in simple whole number ratios
Laws of Multiple Proportions
Whenever the same two elements form more than one compound, the different masses of one element that combine with the same masses of the other elements are in the ratio of small whole numbers