Chemistry Language - Formulas And Nomenclature

Before you can begin to name compounds you must first learn the names of the most common elements. The best way is to prepare a set of flash cards, and drill yourself until you know the symbols and names (including correct spelling) flawlessly.

Element	Symbol	Element	Symbol	Element	Symbol
Hydrogen	H	Flourine	F	Chlorine	Cl
Bromine	Br	Helium	He	Sodium	Na
Potassium	K	Silver	Ag	Lithium	Li
Magnesium	Mg	Calcium	Ca	Tin	Sn
Boron	B	Aluminum	Al	Iron	Fe
Iodine	I	Carbon	C	Silicon	Si
Nickel	Ni	Lead	Pb	Nitrogen	N
Phosphorus	P	Copper	Cu	Barium	Ba
Oxygen	O	Sulfur	S	Zinc	Zn
Chromium	Cr	Neon	Ne	Argon	Ar
Krypton	Kr	Xenon	Xe	Cobalt	Co
Manganese	Mn	Silver	Ag	Gold	Au
Strontium	Sr

At first thought, it may seem difficult to learn the formulas and names of the hundred or so compounds you will encounter in a first year chemistry course. Actually, it is not very difficult if you follow a few systematic rules, which you will need to memorize.

Only UPAC’s names and chemical symbols are allowed during the quiz and exam. No common names are acceptable.

Example I

Chemical Symbol	Common Name	UPAC's Name
H2O2	Hydrogen Peroxide	Dihydrogen Dioxide
H2O	Water	Dihydrogen Monoxide
K2CO3	Potash	Potassium Carbonate

Example II

Correct Symbol	Incorrect Symbol
Al
Mg
Na
Cl
NaCl	NaCl-

Example III

Name	Correct Symbol	Incorrect Symbol
Sulfur Trioxide	SO3	SO3-2

I. BINARY COMPOUNDS COMPOSED OF TWO NONMETALS

Binary compounds are composed of atoms of two different elements. One type of binary compound is composed of two nonmetals and is named by using the elemental name for the first element followed by the name of the second element with its ending changed to "IDE". A prefix is added to each name to indicate the number of atoms of each element in the molecule. The mono prefix can be eliminated if it refers to the first element in the name.

Number of Atoms	Prefix	Number of Atoms	Prefix
1	mono	5	penta
2	di	6	hexa
3	tri	7	hepta
4	tetra

Example:     Name SO₂

Use the elemental name for the first element – sulfur (a prefix is not used since we drop a mono at the beginning of the name) and then use the root of the second element name "ox" followed by “ide” and preceded by “di” to indicate the presence of two oxygen atoms - dioxide. The correct name for SO₂ is sulfur dioxide. The following examples will illustrate some common compounds of this type:

NO2   nitrogen dioxide

N2O4         dinitrogen tetroxide

CO    carbon monoxide

Notice in the name "tetroxide" the "a" from tetra is omitted, and in the name "monoxide" the "o" from mono is omitted.





DRILL I (Note: Answers are given at the end of this handout)

I. Name the following compounds. (correct spelling is required)

	1.	SO2	3.	P2O5	5.	ICl
	2.	CCl4	4.	ClO	6.	SF6

II. Write the correct chemical formulas.

	1.	nitrogen trichloride	3.	oxygen difluoride
	2.	dinitrogen pentoxide	4.	phosphorus pentachloride

DO NOT PROCEED TO NEXT SECTION UNTIL YOU HAVE THOROUGHLY MASTERED PREVIOUS SECTION




II. BINARY COMPOUNDS OF A METAL AND A NONMETAL (Binary Salts)

A second type of binary compound is composed of a metal and a nonmetal. It is named by first naming the metal ion and then the nonmetal ion. As illustrated below, the name of a metal ion is generally the same as the name of the element. Nonmetal ions are named by changing the ending of the element's name to "IDE".

Certain metals tend to form two common ions of different charge. In this case, the charge is indicated using Roman Numerals as shown in Table I below. As an alternative, the ion with the higher charge is named using an "IC" ending and the ion with the lesser charge receives an "OUS". In this second system, the original Latin stem names are often used.

DO NOT USE PREFIXES.


TABLE I CATIONS

Representative Elements (Group A)	Transition Metals (Group B)
Group IA
Alkali Metals
H+ hydrogen Li+ lithium Na+ sodium K+ potassium	Fe2+ iron(II) or ferrous Fe3+ iron(III) or ferric Cu1+ copper(I) or cuprous Cu2+ copper(II) or cupric
Group IIA Alkaline Earths	Pb2+ lead(II) or plumbous
Mg2+ magnesium Ca2+ calcium	Pb4+ lead(IV) or plumbic Sn2+ tin(IV) or stannic
Group IIIA	Sn4+ tin(IV) or stannic
Al3+ aluminum	Hg22+ mercury(I) or mercurous Hg2+ mercury(II) or mercuric
	Ag+ silver Ni2+ nickel Zn2+ Zinc

Nonmetal ions are named using the stem of the element's name and changing the ending to "IDE".

F-	fluoride	O2-	oxide	N3-	nitride	C4-	carbide
Cl-	chloride	S2-	sulfide	P3-	phosphide
Br-	bromide
I-	iodide
H-	hydride

A few of the polyatomic (more than one atom) ions have names that are similar to their monatomic counterparts. These are: CN^-, NH₄⁺ _,   OH^-.

NH4+

ammonium

CN-

cyanide

OH-

hydroxide

When polyatomic ion is used in writing the chemical formula of the compound more then once, place the polyatomic ion inside the parenthesis and then use the subscript that indicate the number of the polyatomic ions necessary to balance the charge of cation

We combine the metal ion with the nonmetal ion in such a way that the sum of the positive and negative charge is zero, or such that the resulting compound is neutral.

Example 1: Let’s write the formula for potassium bromide by using the charges on its constituent elements. Place the element with the positive charge first followed by the element with the negative charge. The charge on the potassium ion is 1+ and the charge on the bromide ion is 1-.

Since the sum of +1 and -1 is zero, the correct formula for electrically neutral compound sodium chloride is KBr.


Example 2: Write the formula for magnesium fluoride. The charge on a magnesium ion is 2+. Therefore, two fluoride ions are required to make a neutral compound.

Mg²⁺ + 2F^-  = MgF₂
   +2 + 2(-1) = 0

Example 3: Write the formula for aluminum oxide. The charge on the aluminum ion is 3+ and the charge on the oxide ion is 2-.

Because +3 and -2 does not equal zero, AlO is not the correct formula. By inspection, it can be seen that 2 atoms of aluminum would give a total of 6 positive units and that three atoms of oxygen would give 6 negative units.

2Al³⁺ + 3O^2-  = Al₂O₃                             
2(3⁺) + 3(2^-)  = 0

Since the sum of +6 and -6 is zero, the correct simplest formula for aluminum oxide is therefore Al₂O₃.

Some examples of naming binary salts are:

NaCl       sodium chlorIDE
KBr         potassium bromIDE
CaI₂       calcium iodIDE
LiF          lithium fluorIDE



DRILL II

I. Name the following compounds: (correct spelling is required)

	1.	MgO	6.	Ba3P2
	2.	K2S	7.	LiH
	3.	FeCl3	8.	Mg3N2
	4.	AgI	9.	CaBr2
	5.	Ca(OH)2	10.	Cu2S

II. Write the correct chemical formulas

	1.	calcium nitride	6.	lithium phosphide
	2.	aluminum oxide	7.	ammonium chloride
	3.	sodium cyanide	8.	barium hydride
	4.	potassium hydroxide	9.	copper(II) sulfide
	5.	tin(IV) or stannic bromide	10.	iron(II) or ferrous iodide

DO NOT PROCEED TO NEXT SECTION UNTIL YOU HAVE THOROUGHLY MASTERED PREVIOUS SECTION



III. TERNARY SALTS

Ternary compounds are composed of three or more elements. Ternary salts are generally composed of a metal cation and an anion that consists of a group of nonmetals rather than just one. These negative ions are often called polyatomic ions. Examples of polyatomic ions are given in Tables IV and V shown below. In general, when the central atom of a polyatomic ion is bound to a higher number of oxygens, the ion name will end with "ATE". If the central atom is bound to fewer oxygens, the ending will be "ITE". To name ternary salts, name the metal cation first, and then the anion.
When polyatomic ion is used in writing the chemical formula of the compound more then once, place the polyatomic ion inside the parenthesis and then use the subscript that indicate the number of the polyatomic ions necessary to balance the charge of cation

C2H3O2-	acetATE	CO32-	carbonATE	PO43-	phosphATE
NO3-	nitrATE	SO42-	sulfATE	MnO4-	permanganATE
NO2-	nitrITE	SO32-	sulfITE	CrO42-	chromATE
		S2O32-	thiosulfATE	Cr2O7 2-	dichromATE

 

ClO-	HYPOchlorITE	BrO-	HYPObromITE	IO-	HYPOiodITE
ClO2-	chlorITE	BrO2-	bromITE	IO2-	iodITE
ClO3-	chlorATE	BrO3-	bromATE	IO3-	iodATE
ClO4-	PERchlorATE	BrO4-	PERbromATE	IO4-	PERiodATE

Some examples of ternary compounds are:

+1 ‑ 1 = 0
NaC2H3O2	NaC2H3O2	sodium acetATE

The charge on the ion gives the combining power of the ion taken as a unit.

2(+1) ‑ 2 = 0
Na2CO3	Na2CO3	sodium carbonATE

+2 + 2(-1) = 0
Ca(ClO2)2	Ca(ClO2)2	calcium chlorITE

2(+3) + 3(-2) = 0
2Al+3 + 3SO4-2	Al2(SO4)3	aluminum sulfATE

DRILL III

1. Name the following compounds (watch your endings)

1.	Ca3(PO4)2	8.	Cu(C2H3O2)2	15.	NaClO4
2.	KNO3	9.	KCN	16.	CuNO2
3.	BaCO3	10.	Na3PO4	17.	Al(ClO2)3
4.	LiBrO2	11.	K2SO4	18.	Ca(IO)2
5.	MgSO3	12.	Fe(BrO)3	19.	Ba(BrO4)2
6.	Mg(IO4)2	13.	AgClO3	20.	Li2CO3
7.	NaIO3	14.	SnSO4

II. Write the correct formulas for the following compounds:

1.	lithium hypobromite	5.	aluminum phosphate	9.	magnesium chlorate
2.	tin(II) nitrate	6.	iron(III) sulfite	10.	lithium acetate
3.	sodium carbonate	7.	copper(II) phosphate
4.	ammonium sulfate	8.	potassium iodite

DO NOT PROCEED TO NEXT SECTION UNTIL YOU HAVE THOROUGHLY MASTERED PREVIOUS SECTION




IV. BINARY ACIDS - The water solutions of compounds composed of hydrogen and a nonmetal

RULE: Acids composed of hydrogen and a nonmetal are named by putting the prefix HYDRO before the root of the name of the nonmetal and adding the suffix IC followed by the word ACID.

For example: When hydrogen chloride (HCl) is dissolved in water, we get hydrochloric acid.

	HF(aq)	HYDROfluorIC acid
	HC1(aq)	HYDROchlorIC acid
	HBr(aq)	HYDRObromIC acid
	HI(aq)	HYDROiodIC acid
	H2S(aq)	HYDROsulfurIC acid

NOTE: The formulas of binary acids must be followed by (aq). The (aq) means aqueous or dissolved in water. Without the (aq) it would represent a gas. For instance, HCl is hydrogen chloride gas.


V. ACIDS CONTAINING OXYGEN - Compounds of hydrogen and a polyatomic ion (with oxygen present)

RULES:

1. If there is only one oxygen acid, the name is that of the characteristic element followed by the suffix IC.

2. If there are two oxygen acids, the name of the one with the larger number of oxygen atoms ends in IC, and the name of the one with the smaller number of oxygen atoms ends in OUS.

3. If there are four oxygen acids, like the oxyacids of the halogen family, the acid with the greatest number of oxygens is designated by the prefix PER- and suffix -IC, the one with the next fewer oxygens has the suffix -IC, the one with the next fewer has the suffix –OUS, and the fewest oxygens acid is designated with the prefix HYPO- and the suffix -OUS.

For example:

	HNO3 is nitrIC acid	HBrO is HYPObromOUS acid
	HNO2 is nitrOUS acid	HBrO2 is bromOUS acid
	H2SO4 is sulfurIC acid	HBrO3 is bromIC acid
	H2SO3 is sulfurOUS acid	HBrO4 is PERbromIC acid
	HC2H3O2 is acetIC acid	H3PO4 is phosphorIC acid

NOTE: Ternary acid formulas are not usually followed by (aq). It is assumed that they are dissolved in water.



DRILL IV

I. Name each of the following:

	1.	H2S (aq)	5.	H3PO4
	2.	HC2H3O2	6.	HI(aq)
	3.	HBrO	7.	HIO3
	4.	HF(aq)	8.	HBrO2

II. Give the chemical formula of each of the following:

	1.	nitrous acid
	2.	hydrobromic acid
	3.	perbromic acid
	4.	iodous acid
	5.	chloric acid

DO NOT PROCEED TO THE NEXT SECTION UNTIL YOU HAVE THOROUGHLY MASTERED THIS SECTION.



VI. ACID SALTS

When a metal replaces one or more hydrogen atoms of an acid, acid salt is formed. To name such salt, we have to identify the number of remaining number of hydrogen atoms in the salt using appropriate prefix ( see page 1).

For example:

H₃PO₄ is phosphoric acid

NaH₂PO₄ is sodium Dihydrogen phosphate

Na₂HPO₄ is sodium MONOhydrogen phosphate

Na₃PO₄ is sodium phosphate

If the acid contains only two hydrogen atoms, then only two acid salts are possible. These salts could be named by the method described above, but a most common method used by chemists, is to add prefix bi to the name of the anion.

For example:

H₂CO₃ is carbonic acid

NaHCO₃ is sodium MONOhydrogen carbonATE or sodium BIcarbonATE

Na₂CO₃ is sodium carbonATE


VII. DIATOMIC MOLECULES

Seven elements exist naturally as diatomic molecules. They are named by identifying the element preceded by the word "molecular".

Examples:

	O2  ‑ molecular oxygen	H2  ‑ molecular hydrogen
	I2    ‑ molecular iodine	F2   ‑ molecular fluorine
	Cl2  ‑ molecular chlorine	Br2  ‑ molecular bromine
	N2   ‑ molecular nitrogen

VIII. HYDRATES SALTS

Some ionic salts are hydrated, chemically bound with water molecules. These water molecules are called waters of crystallization. In naming a specific hydrated salt, first name the ionic salt according to all rules learned in the above sections, then use the appropriate prefix to indicate the number of water molecules, and finally add the term “hydrate”. For example, MgSO4 . 7H2O has seven waters of crystallization per one mole of magnesium sulfate. The correct name of this compound is magnesium sulfate heptahydrate.








VIII. PRACTICE QUIZ

1. Give the correct name of each of the following.

a.	KCl
b.	Na2CO3
c.	CCl4
d.	PBr3
e.	NaNO2
f.	ZnSO3
g.	KIO4
h.	NiS
i.	Li3N
j.	Cu(OH)2

2. Give the chemical formula of each of the following:

a.	sodium oxide
b.	iron(II) phosphate
c.	dinitrogen monoxide
d.	potassium acetate
e.	barium hypochorite
f.	calcium phosphide
g.	molecular oxygen
h.	silver nitrate
i.	ammonium sulfate
j.	magnesium cyanide

ANSWERS

DRILL I

I.	1.	sulfur dioxide	4.	chlorine monoxide
	2.	carbon tetrachloride	5.	iodine monochloride
	3.	diphosphorus pentoxide	6.	sulfur hexafluoride

II.

1.

NCl3

2.

N2O5

3.

OF2

4.

PCl5

DRILL II

I.	1.	magnesium oxide	6.	barium phosphide
	2.	potassium sulfide	7.	lithium hydride
	3.	ferric or iron(III) chloride	8.	magnesium nitride
	4.	silver iodide	9.	calcium bromide
	5.	calcium hydroxide	10.	cuprous or copper(I) sulfide

II.	1.	Ca3N2	2.	Al2O3	3.	NaCN	4.	KOH	5.	SnBr4
	6.	Li3P	7.	NH4Cl	8.	BaH2	9.	CuS	10.	FeI2

DRILL III

I.	1.	calcium phosphate	11.	potassium sulfate
	2.	potassium nitrate	12.	ferric hypobromite or iron (III) hypobromite
	3.	barium carbonate	13.	silver chlorate
	4.	lithium bromite	14.	stannous sulfate or tin (II) sulfate
	5.	magnesium sulfite	15.	sodium perchlorate
	6.	magnesium periodate	16.	cuprous nitrite or copper (I) nitrite
	7.	sodium iodate	17.	aluminum chlorite
	8.	cupric acetate or copper(II) acetate	18.	calcium hypoiodite
	9.	potassium cyanide	19.	barium perbromate
	10.	sodium phosphate	20.	lithium carbonate

II.	1.	LiBrO	2.	Sn(NO3)2	3.	Na2CO3	4.	(NH4)2SO4	5.	AlPO4
	6.	Fe2(SO3)3	7.	Cu3(PO4)2	8.	KIO2	9.	Mg(ClO3)2	10.	LiC2H3O2

DRILL IV

I.	1.	hydrosulfuric acid	5.	phosphoric acid
	2.	acetic acid	6.	hydroiodic acid
	3.	hypobromous acid	7.	iodic acid
	4.	hydrofluoric acid	8.	bromous acid

II.

1.

HNO2

2.

HBr(aq)

3.

HBrO4

4.

HIO2

5.

HClO3

PRACTICE QUIZ

1.	a.	potassium chloride	f.	zinc sulfite
	b.	sodium carbonate	g.	potassium periodate
	c.	carbon tetrachloride	h.	nickel sulfide
	d.	phosphorus tribromide	i.	lithium nitride
	e.	sodium nitrite	j.	copper (II) hydroxide
2.	a.	Na2O	f.	Ca3P2
	b.	Fe3(PO4)2	g.	O2
	c.	N2O	h.	AgNO3
	d.	KC2H3O2	i.	(NH4)2SO4
	e.	Ba(ClO)2	j.	Mg(CN)2