Ionic & Acids Naming & Formulas

Naming &

Formula Notes

Objective 1: WRITING
CHEMICAL FORMULAS

►

Symbols are used to represent elements. One or two
letters symbolize the element, the first letter is capital,
second letter if used is lower case. Unq, Unh, etc. are
used for the most recent synthetic elements.

►

Chemical formulas are used to represent compounds; showing the ratio of
atoms of each element in the compound.

1) Letter symbols represent elements.

2) Number subscripts represent the number of atoms of each element.

Objective 2: NUMBER OF
ATOMS IN A COMPOUND

► Given a formula, identify the number of

each type of atom in the compound.

► BaCl2 - _____ barium atom, _____ chlorine atoms

► CoCO3 - ______ cobalt atom, ______ carbon atom,

_______ oxygen atoms

► (NH4)2C2O4 - _____ nitrogen atoms, _______

hydrogen atoms, ______ carbon atoms, _______
oxygen atoms

Objective 3: LAW OF
DEFINITE PROPORTIONS
►

Law of definite proportions: The elements
composing a compound are always found in the
same ratio by mass.

►

H2O - water - always has twice as many hydrogen
atoms as oxygen per molecule of water, therefore
the ratio of their masses is always the same.

Vocabulary

COMPOUND

Ternary

Compound

Binary

Compound

2 elements

elements

more than 2

Objective 4: NAMING IONIC
COMPOUNDS
1) BINARY COMPOUNDS - Metal - Nonmetal

Metal ion

Nonmetal ion

+ ion

- ion

uses its name

use root name & -ide suffix

Ionic Nomenclature

2) BINARY COMPOUNDS – Transition Metal - Nonmetal
Transition Metal ion

Nonmetal ion

+ ion

- ion

uses its name with

use root name & -ide suffix

a Roman numeral

to indicate charge

►

USE THE CHARGE OF THE ANION (NEGATIVE ION) TO DETERMINE THE CHARGE OF
THE TRANSITION METAL ION- remember that the overall charge is zero.

►

You must memorize that Ag is 1+ and Zn is 2+. These metals do not have multiple ion
charges, so you need to know them.

If a metal is not in group 1 or 2 or Al, consider it
a transition metal!!

Example

PbCl2

Sn3N2

Ionic Nomenclature

3) POLYATOMIC IONS - a group of atoms acting like one ion. You have been given a list of names and
charges of the most common polyatomic ions.

- metal-polyatomic ion: metal uses its name and polyatomic ion use its name

►EXAMPLE: Mg(NO3)2

►Na2SO4

►- polyatomic ion-nonmetal: polyatomic ion uses its name and nonmetal ion uses its root name
with the -ide suffix.

►EXAMPLE: NH4Cl

►- polyatomic ion-polyatomic ion: both polyatomic ions keep their names

►EXAMPLE: NH4NO3

►(NH4)2SO4

Ionic Nomenclature

►

Consider the following:

►Does it contain a polyatomic ion?

►-ide, 2 elements ⇒ no

►-ate, -ite, 3+ elements ⇒ yes

►Does it contain a Roman numeral?

►Check the table for metals not in Groups 1 or 2.

►No prefixes!

Objective 5: WRITING FORMULAS
FOR IONIC COMPOUNDS

1. BINARY COMPOUNDS - all end in -ide. This ending lets you
know that the compound only contains two elements.

►

A. Metal-Nonmetal

magnesium chloride

potassium sulfide

►

B. Transition metal-Nonmetal- the Roman numeral indicates
the ion charge for the transition metal

iron(II) chloride

lead(IV) oxide

WRITING FORMULAS FOR
IONIC COMPOUNDS
2. POLYATOMIC COMPOUNDS

►

A. Polyatomic ion-Nonmetal - ends in -ide

ammonium bromide

ammonium sulfide

►

B. Metal-Polyatomic ion - ends in either -ate or -ite

potassium chlorate

sodium sulfite

WRITING FORMULAS FOR
IONIC COMPOUNDS

C. Transition metal-Polyatomic ion - ends in either -ate or -ite

lead(II) nitrite

chromium(III) oxalate

►

D. Polyatomic ion-Polyatomic ion - ends in either -ate or -ite

ammonium dichromate

ammonium chlorite

►

NOTE: You will need to remember that hydroxide (OH-),
peroxide (O2

2-) and cyanide (CN-) are polyatomic ions which end

in -ide. Most of the time the –ide ending signifies a nonmetal
ion

Ionic Formulas

►

Write the names of both ions, cation first. Don’t show charges in the final
formula.

►

Overall charge must equal zero.
►If charges cancel, just write symbols.

►If not, use subscripts to balance charges.

►

Use parentheses to show more than one polyatomic ion.

►

Stock System - Roman numerals indicate the ion’s charge.

Ionic Nomenclature

Common Ion Charges

Multiple Choice

When naming ionic compounds with transition metals you need to include roman numerals to show the _____ of the metal..

• atomic number

• mass number

• charge

• ionization energy

Multiple Choice

Which of the following combinations would need roman numerals in the name?

• potassium + fluorine

• beryllium + oxygen

• boron + iodine

• gold + oxygen

Multiple Choice

LiBr is called

• lithium bromine

• lithium (I) bromine

• lithium bromide

• lithuim (I) bromide

Multiple Choice

Name the following ionic compound: Cs₂S

• cesium sulfide

• cesium sulfate

• cesium II sulfate

• cesium II sulfide

Objective 6: NAMING AND
WRITING FORMULAS FOR ACIDS

A. Given the acid name write the formula.

THE POSITIVE ION FOR ALL ACIDS IS HYDROGEN, H+.

►

1. BINARY ACIDS - contains only two elements; H and a
nonmetal; Hydro- prefix indicates the acid is binary. The
ending of the second element (a nonmetal) has been
changed to -ic.

►

hydrochloric acid

►

hydrophosphoric acid

►

hydrosulfuric acid

Objective 6: NAMING AND
WRITING FORMULAS FOR ACIDS
2. POLYATOMIC ACIDS - contain three or more elements; H and a
polyatomic ion; -ous or -ic suffix without hydro indicate the acid is
polyatomic.

A. -ous suffix indicates an -ite form of a the polyatomic ion

►

nitrous acid

►

sulfurous acid

►

phosphorus acid

B. -ic suffix without hydro indicates the -ate form of a polyatomic ion

►

nitric acid

►

sulfuric acid

►

phosphoric acid

Objective 6: NAMING AND
WRITING FORMULAS FOR ACIDS

B. To name an acid given its formula

1. If it is binary, prefix hydro- and the -ic suffix on the second
element's root name

►

HF

►

HCl

2. If the acid is polyatomic (more than 2 elements), then look up the
polyatomic ion

A. If the polyatomic ion ends in -ate, add -ic in place of the -ate

►

H3PO4

►

H2SO4

B. If the polyatomic ion end in -ite , add -ous in place of -ite.

►

HNO2

►

H2SO3

Multiple Choice

When naming acids with poly-atomic ions, change "-ite" to:

• -ate

• -ic

• -ous

• -ite

Multiple Choice

When naming acids with poly-atomic ions, change "-ate" to:

• -ate

• -ic

• -ous

• -ite

Multiple Choice

Name HF

• hydrofluoric acid
• Hypofluoric acid
• hydrogen fluorine acid
• fluoric acid

Multiple Choice

What is the formula for hydrochloric acid?

• HCl
• HClO
• H₃ClO₃
• HClO₃