9-1 NotesNaming Ions

Monatomic Ions

Ionic compounds consist of a positive ion (a metal) bonded to a negative ion (a nonmetal)Ex. KBr

Monatomic ions consists of a single atom that has lost or gained electron(s)Ex. Potassium ion lost an electron, while

the Bromide ion gained an electron

Cations

Cations are positively charged ions that occur when atoms lose electrons

The # of electrons lost will correspond to the group # on the periodic table Ex. Sodium in group 1 will lose 1 electron

Naming Cations – the name is the same as the element the ion is formed from Ex. Sodium forms the sodium cation

Identify the cation of the following elements: Ca, Rb, Al, Li, Sr

Anions

Anions are negatively charged ions that occur when atoms gain electrons

Nonmetals in groups 5-7 form anions The charge is determined by subtracting 8 from

the group #Ex. Oxygen is in group 6, therefore, 6-8 = -2

Naming Anions – the end of the element’s name changes to –ideEx. Bromine forms the Bromide anion

Identify the anions of the following elements: P, Se, I, F, N

Ions of Transition Metals

Many of the transition metals form more than 1 cation

The charges must be determined from the number of electrons lostEx. Iron can lose 2 electrons and form Fe2+ or

it can lose 3 electrons and form Fe3+

See Table 9.2 p. 255

Ions of Transition Metals

There are 2 ways to name these ions1. Stock System – uses roman numerals to indicate

the charge on the ionEx. Fe2+ is Iron (II) while Fe3+ is Iron (III)

2. Classical name – uses the Latin form of the element and a suffix to indicate the chargeThe suffix –ous indicates the lower of the 2 charges

The suffix –ic indicates the higher of the 2 charges

Ex. Fe2+ is the ferrous ion while Fe3+ is the ferric ion

A few transition metals only form 1 ion and these are named like all other cationsEx. Silver (Ag+), Zinc (Zn2+)

Polyatomic Ions

Polyatomic ions are composed of more than 1 atom

Ex. Nitrate (NO3-) consists of both nitrogen

and oxygen

The names of most polyatomic ions end in -ite or –ate

The use of –ite or –ate as the ending usually depends on the # of Oxygen atoms in the ion

Ex. Nitrate (NO3-) has more oxygen atoms

while Nitrite (NO2-) has less oxygen atoms

Polyatomic Ions

If the formula for a polyatomic ion begins with an H it includes a H+The charge is the sum of the two ions

Ex. Hydrogen carbonate (HCO3-) is the sum of H+

and CO32-

Most polyatomic ions are negatively charged

The 1 exception is NH4+ which is ammonium

See Table 9.3 p. 257

9-2 NotesNaming and Writing Formulas for Ionic Compounds

Naming Binary Ionic Compounds A binary compound is composed of 2 elements and

can either be ionic or molecular

1st step in naming an ionic compound is making sure it is composed of a monatomic metal cation and a monatomic nonmetal anion

When naming, simply place the cation name first followed by the anion name

Ex. KBr is Potassium bromide, while Na2O is sodium oxide

When the cation is a transition metal with more than 1 charge, you must indicate which ion is being used

Ex. Cu2O is Copper (I) oxide, while CuO is Copper (II) oxide

Writing Formulas for Binary Ionic Compounds

Step 1: Write the symbol of the cation and then the anion.

Step 2: Add whatever subscripts are needed to balance the charges Make sure the subscripts are reduced

There are two methods to balance charges 1. Find the least common multiple of the charges

2. The crisscross method: the numerical value of the charge of each ion is crossed over and becomes the subscript for the other ion

Write the formulas for the following: Iron (III) oxide and Calcium bromide

Compounds with Polyatomic Ions

Naming ionic compounds with polyatomic ions is the same as binary compoundsWrite the cation first followed by the anion

Name the following: LiCN, AgNO3, (NH4)2C2O4

Compounds with Polyatomic Ions

Step 1: Write the symbol of the cation and then the anion.

Step 2: Add whatever subscripts are needed to balance the charges

Step 3 (if needed): If more than 1 polyatomic ion is needed to balance the charges you must use parenthesesEx. Calcium Nitrate

Write the formulas for the following: Lithium carbonate & Aluminum nitrite

9-3 NotesNaming and Writing Formulas for Molecular Compounds

Review

How do we do the following?Name Ionic Compounds

Ex. KBr, Na3PO4, Fe(NO3)3

Write Formulas for Ionic Compounds

Ex. Sodium nitride, Ammonium oxide, Copper (II) nitrite

Naming Binary Molecular Compounds

Binary molecular compounds are composed of molecules, not ions, and consist of 2 nonmetals

Due to various ways of sharing electrons the same elements can be used to make different compounds

Ex. CO and CO2

How do you name these so you can tell there is a difference?

Naming Binary Molecular Compounds

Prefixes are used to represent the number of atoms of each element that can be found in a molecular compound

The Rules: 1. Confirm the compound is molecular

2. Name the elements in the order listed in the formula

3. Use the appropriate prefix to indicate the # of each element (see table 9.4 p. 269)

Exception: Do not use mono- on the 1st element

4. Change the ending of the 2nd element to –ide

Name the following: CO, CO2, N2O5, CCl4

Writing Formulas for Molecular Compounds

Step 1: Write the correct symbols for the two elements

Step 2: Use the prefixes in the name to determine the subscript of each element in the formula

Write the formula for the following: Dinitrogen tetraoxide, Dihydrogen monoxide, Phosphorus pentachloride

9-4 NotesNaming and Writing Formulas for Acids and Bases

Review

How do we do the following?Name Ionic Compounds

Ex. (NH4)3PO4, Cr(NO2)3

Write Formulas for Ionic CompoundsEx. Potassium sulfate, Iron (III) oxide

Name Molecular Compounds

Ex. CO2, CCl4

Write Formulas for Molecular CompoundsEx. Boron Trichloride, Dinitrogen tetrahydride

Naming Acids

An acid is a compound that contains 1 or more hydrogen atoms and produces H+ when dissolved in water

The general form of an acid is HnX

n is the subscript indicating how many Hydrogen ions are needed

X is the monatomic or polyatomic anion

Naming Acids – The Rules

1. If the anion ends in –ide, the acid name will begin with hydro-. The –ide will be replaced by –ic and followed by acidEx. HCl

2. If the anion ends in –ite, the acid name is the stem of the anion with the suffix –ous and followed by acid

Ex. H2SO3

3. If the anion ends in –ate, the acid name is the stem of the anion with the suffix –ic and followed by acid

Ex. HNO3

Name the following: HF, HNO2, HMnO4

Writing Formulas for Acids

Use the rules for writing the names of acids in reverse to write the formulas for acids

Remember – add subscripts to balance the formulaEx. Rule 1 – Hydrobromic acid

Ex. Rule 2 – Phosphorous acid

Ex. Rule 3 – Sulfuric acid

Write formulas for the following: Permanganic acid, Nitrous acid, hydrosulfuric acid

Bases

A base is an ionic compound that produces hydroxide ions when dissolved in water

Naming bases and writing formulas is the same as any other ionic compound

Name the following: Ba(OH)2, KOH

Write the formulas for the following: Strontium hydroxide, Copper (II) hydroxide