CH 1000 MOD 2 REVIEW

CH1000 Fundament als of Chemistry Module 2 – Chapter 6

Common and Systematic Names

• Chemical nomenclature is the systematic naming of chemical compounds • Common names are historical names of compounds which are not based

on systematic rules • Common names are often used because systematic names are too long

and technical for everyday use • Chemists prefer systematic names that precisely identify the chemical

composition of compounds. • Example CaO

• Common name: lime • Systematic name: calcium oxide

Naming Flowchart

We will focus on nomenclature of inorganic compounds

Elements and Ions

• The formula for most elements is the symbol of the element off of the periodic table. • Diatomic molecules are an exception:

• Two other elements also exist in polyatomic arrangements:

Naming Anions

•Remember from Chapter 5 that any neutral atom that gains an electron is called an anion •When naming anions, change the element ending to -ide

Symbols of the Elements •Each element has an abbreviation called a symbol.

•The first letter of a symbol must always be capitalized.

•If a second letter is needed, it should be lowercase.

Predicting Ion Charge from Periodic Table

•Metals form cations •The positive charge is equal to the group number

Predicting Ion Charge from Periodic Table

•Nonmetals form anions •The negative charge is equal to 8 – the group number

Writing Formulas from Names of Ionic Compounds

•Ionic compounds contain both a cation and an anion.

•Ionic compounds must have a net charge of 0

•The sum of charges of the cations and anions in an ionic compound equal 0

•Rules for writing formulas for ionic compounds: • Write the metal ion followed by the

nonmetal ion formula • Combine the smallest whole numbers

of each ion to provide an overall charge equal to zero

• Write the compound formula for the metal and nonmetal, using subscripts determined from Step 2 for each ion

Naming Ionic Binary Compounds •Binary compounds containing a metal which forms only one cation

•By convention, the cation is written/named first followed by the anion

•Rules for naming binary ionic compounds: • Name the cation • Write the anion root and

add the –ide suffix

Naming Compounds Containing Metals with

Multiple Charges

•Rules for Naming Compounds Involving Metals that Could Form Multiple Charges • Write the cation name. • Write the cation charge in Roman numerals in parentheses. • Write the root of the anion and use the –ide suffix.

•Exception: for metals that only form two cations, a Latin root with either an –ous or –ic suffix can also be used.

Formula Name Classical Name Formula Name Classical Name

Cu+ Copper(I) cuprous Sn2+ Tin(II) stannous

Cu2+ Copper(II) cupric Sn4+ Tin(IV) stannic

Fe2+ Iron(II) ferrous Pb2+ Lead(II) plumbous

Fe3+ Iron(III) ferric Pb4+ Lead(IV) plumbic

Naming Molecular Compounds

•Molecular compounds contain two nonmetals •Rules for naming molecular compounds: • Write the name for the first element, including the appropriate prefix

(mono is rarely used). • Write the name for the second element, including the appropriate prefix

and -ide ending (mono is used for the 2nd element).

Prefix Number Prefix Number mono 1 hexa 6

di 2 hepta 7

tri 3 octa 8 tetra 4 nona 9 penta 5 deca 10

Naming Binary Acids

Rules for naming Binary Acids:

Write the prefix hydro followed by the root of the second element and add an –ic suffix Add the word acid

Hydrogen is always written first in an acid formula.

This is the indicator that it is an acid

Certain binary compounds containing hydrogen behave as acids in water and have special names.

HCl(g) is hydrogen chloride HCl(aq) is hydrochloric acid

Naming Polyatomic Ions

•A polyatomic ion is anion that contains two or more elements •The names, formulas and charges of common polyatomic ions should be learned. •Rules for naming compounds containing polyatomic ions • Name the cation • Name the anion

Name Formula Charge Name Formula Charge Acetate C2H3O2- -1 Cyanide CN- -1

Ammonium NH4+ +1 Dichromate Cr2O72- -2 Hydrogen Carbonate HCO3

- -1 Hydroxide OH- -1

Hydrogen Sulfate HSO4

- -1 Nitrate NO3- -1

Bromate BrO3- -1 Nitrite NO2- -1 Carbonate CO32- -2 Permanganate MnO4- -1 Chlorate ClO3- -1 Phosphate PO43- -3

Chromate CrO42- -2 Sulfate SO42- -2 Sulfite SO32- -2

Naming Oxyanions •Oxyanions are polyatomic ions that contain oxygen •Often end in suffix –ate or –ite •-ate compounds contain more O atoms than ite compound(s) •For elements that form multiple ions with oxygen, prefixes are also needed: • Per: add one oxygen to the –ate root • Hypo – subtract one oxygen from the –

ite root

Anion Formula Anion Name

Anion Formula Anion Name

ClO- hypochlorite HClO hypochlorous acid

ClO2- chlorite HClO2 chlorous acid

ClO3- chlorate HClO3 chloric acid

ClO4- perchlorate HClO4 perchloric acid

More Complicated Polyatomics

•Inorganic ions can be formed from more than 3 elements •The same method is used as before: • Identify the ions and name in order • Cations before anions

Compound Ions Name

NaHCO3 Na+; HCO3- Sodium hydrogen

carbonate

NaHS Na+; HS- Sodium hydrogen sulfide

MgNH4PO4 Mg2+; NH4+;

PO43- Magnesium ammonium phosphate

NaKSO4 Na+; K+; SO42- Sodium potassium

sulfate

Naming Acids

• Acids generally begin with hydrogen • To recognize oxyacids, make sure: • H is the first element in the formula • The compound contains a polyatomic ion with oxygen

• The following modifications are made to the name of the acid: • -ate ions are changed to –ic acids • -ite ions are changed to –ous acids • -ic acids contain one more oxygen than –ous acids

Naming Acids Flowchart

Reading Review

What type of ions do metals form?

What type of ions do nonmetals form?

What is the chemical formula for potassium sulfide?

Name the compound CrCl3.

Acids often begin with what element?