Chemical Formula

Chemical formula is a way to describe chemical ratios of atoms that make up a specific chemical compound or molecule in chemistry. Chemical element symbols, numbers, and sometimes other symbols, such as parentheses, dashes, brackets, commas, plus (+), and minus (-) signs, are used to represent the chemical elements, atoms, or ions. A chemical substance that contains atoms from at least two different elements is referred to be a chemical compound. Chemical compounds and molecules both contain many atoms, but unlike chemical compounds, a molecule can just be made up of atoms from the same element.

In this article, we have covered, Definition of Chemical Formula, Importance of Chemical Formula, Types of Chemical Formulae, and others in detail.

What is Chemical Formula?

A chemical formula is a representation of a substance’s molecular composition in terms of the symbols representing the components that make up the molecule. A molecular formula is another name for a chemical formula.

An element’s or a compound’s chemical formula can be used. A chemical formula is a technique of presenting information on the chemical proportions of atoms that make up a chemical compound or molecule using chemical element symbols, numbers, and other symbols like parentheses, dashes, brackets, and commas.

Importance of Chemical Formula

The importance of Chemical Formulas can be understood as,

• Compound’s name is represented by a formula.
• Names of all the elements in the molecule are given in formulae.
• Number of atoms of each element contained in a molecule is given by formulae.
• One molecule of a compound is represented by a formula.
• Formulae denote a definite mass of a substance.

Types of Chemical Formulae

There are different types of chemical formulae based on the composition of chemical compounds:

• Molecular Formula
• Empirical formula
• Structural formula

Molecular Formula

Amount of elements in a substance can be determined from its molecular formula. The periodic table’s symbols are used to represent the elements in molecular formulae, and a subscript is used to indicate how many atoms of each element are present in the molecule.

Example:

• Molecular formula of Urea is CH₄N₂O which gives exact number of constituent atoms (i.e Carbon, Hydrogen and Nitrogen in one Urea molecule
• Molecular formula of Acetic Acid is CH₃COOH
• Molecular formula of Glucose is C₆H₁₂O₆

Empirical Formula

Ratio of the elements present in a chemical compound is represented by its empirical formula. Usually, empirical formulas are developed by the evaluation of experimental data.

Example:

• Empirical formula of Urea is CH₄N₂O
• Empirical formula of Acetic Acid is CH₂O
• Empirical formula of Glucose is CH₂O

Structural Formula

Structural formula of a chemical compound gives understanding of the arrangement of the atoms in the molecule.

Example:

Structural formula of Urea is shown below,

Structural formula of Acetic Acid is shown below,

How to Write Chemical Formula?

A binary compound is composed of two different elements only. Formulae of binary compounds can be written with the help of valency of elements since both types of atoms forming the compound must lose, gain or share the same number of electrons.

Points to be considered to write the molecular formula

• Determine the valency of the elements present in the compound.
• Write the chemical formula such that the sums of the valency of the two elements are equal. Do this by determining the lowest common multiple of the two valency.
• Always place metals first in the formula.

Chemical Formula of Rust

Elements present in Rust are Iron and Oxygen. Then, 

Symbol	Iron, Fe (26)	Oxygen, O (8)
Valency	3	2

Lowest common multiple of valency is 6. Therefore,

Fe = 2 × 3 = 6

O = 3 × 2 = 6

This implies that the chemical formula is Fe₂O₃

Chemical Formula of Aluminium Oxide

The elements present in Aluminium Oxide are Aluminium and Oxygen. Then, 

Symbol	Aluminium, Al (13)	Oxygen, O (8)
Valency	3	2

The lowest common multiple of valency is 6. Therefore,

Al = 2 × 3 = 6

O = 3 × 2 = 6

This implies that the chemical formula is Al₂O₃

Chemical Formula of Methane

Elements present in Methane are Carbon and Hydrogen. Then, 

Symbol	Carbon, C (6)	Hydrogen, H (1)
Valency	4	1

Lowest common multiple of valency is 4. Therefore,

C = 1 × 4

H = 4 × 1

This implies that the chemical formula is CH₄

Chemical Formula of Sodium Chloride

Elements present in Sodium Chloride are Carbon and Hydrogen. Then, 

Symbol	Sodium, Na (11)	Chlorine, Cl (17)
Valency	1	1

Lowest common multiple of valency is 4. Therefore,

Na = 1

Cl = 1

This implies that the chemical formula is CH₄

Chemical Formula of Calcium Oxide

Elements present in Calcium Oxide are Calcium and Oxygen. Then,

Symbol	Calcium, Ca (20)	Oxygen, O (8)
Valency	2	2

Lowest common multiple of valency is 2. Therefore.

Ca = 1 × 2

O = 1 × 2

This implies that the chemical formula is CaO.

Chemical Formula of Some Common Compounds

Chemical Formula of some common compounds are:

• Chemical formula of Plaster of Paris: CaSO₄.1/2H₂O
• Chemical formula of Bleaching Powder: CaOCl₂
• Chemical formula of Alcohol: C₂H₅OH (Ethyl Alcohol)

Chemical Formula Table

The table given below gives the chemical symbol and molecular weight of some common compounds

Compound Name	Chemical Symbol	Molecular Weight (g/mol)
Acetic acid	CH3COOH	60.052
Hydrochloric acid	HCl	36.458
Sulfuric acid	H2SO4	‎98.072
Ammonia	NH3	17.031
Nitric acid	HNO3	63.012
Phosphoric acid	H3PO4	97.994
Sodium phosphate	Na3PO4	119.976
Calcium carbonate	CaCO3	100.086
Ammonium sulfate	(NH4)2SO4	132.134
Carbonic acid	H2CO3	62.024
Sodium bicarbonate	NaHCO3	84.0066
Sodium hydroxide	NaOH	39.997
Calcium hydroxide	Ca(OH)2	74.092
Ethanol	C2H5OH	46.069
Hydrobromic acid	HBr	80.912
Nitrous acid	HNO2	‎47.013
Potassium hydroxide	KOH	56.11
Silver nitrate	AgNO3	169.872
Sodium carbonate	Na2CO3	105.988
Sodium chloride	NaCl	58.44
Magnesium hydroxide	Mg(OH)2	58.319
Methane	CH4	16.043
Nitrogen dioxide	NO2	30.006
Sodium nitrate	NaNO3	84.994
Aluminium sulfate	Al2(SO4)3	342.15
Aluminium oxide	Al2O3	101.96
Ammonium nitrate	NH4NO3	80.043
Ammonium phosphate	(NH4)3PO4	132.056
Barium hydroxide	Ba(OH)2	171.341
Carbon tetrachloride	CCl4	153.811
Citric acid	C6H8O7	192.123
Hydrocyanic acid	HCN	‎27.026
Salicylic Acid	C7H6O3	138.121
Hydroiodic acid	HI	127.91
Hypochlorous acid	HClO	52.457
Magnesium phosphate	Mg3(PO4)2	262.855
Sodium acetate	C2H3NaO2	82.0343
Sodium sulfate	Na2SO4	‎142.036
Sucrose	C12H22O11	342.2965
Potassium nitrate	KNO3	101.102
Ammonium bicarbonate	NH4HCO3	96.086
Ammonium chloride	NH4Cl	53.489
Ammonium hydroxide	NH4OH	35.046
Calcium nitrate	Ca(NO3)2	164.088
Calcium oxide	CaO	56.0774
Carbon monoxide	CO	28.01
Phenol	C6H6O	94.11
Hydrogen peroxide	H2O2	34.0147
Magnesium chloride	MgCl2	95.211
Potassium chloride	KCl	74.5513
Potassium iodide	KI	166.0028
Sulfur dioxide	SO2	64.066
Calcium acetate	C4H6O4Ca	158.17
Iron oxide	Fe2O3	159.69
Potassium carbonate	K2CO3	138.205
Silver chloride	AgCl	‎143.318
Sodium iodide	NaI	149.894
Sodium oxide	Na2O	61.9789
Zinc nitrate	Zn(NO3)2	189.388
Magnesium nitrate	Mg(NO3)2	148.313
Silicon dioxide	SiO2	60.083
Ammonium acetate	C2H3O2NH4	77.083
Benzene	C6H6	78.11
Methyl Ethyl Ketone	C4H8O	72.107
Trichloroacetic acid	C2HCl3O2	163.38
Magnesium sulfate	MgSO4	120.361
Methanol	CH3OH	32.04
Sodium sulfite	Na2SO3	126.043
Sulfur trioxide	SO3	80.057
Aluminium phosphate	AlPO4	121.951
Dinitrogen monoxide	N2O	44.013
Potassium dichromate	K2Cr2O7	294.185
Sodium bromide	NaBr	102.894
Sodium hypochlorite	NaClO	74.439
Zinc acetate	Zn(CH3COO)2(H2O)2	183.48
Zinc chloride	ZnCl2	136.286
Zinc hydroxide	Zn(OH)2	99.424
Magnesium carbonate	MgCO3	84.313
Potassium chlorate	KClO3	122.545
Hydrazine	N2H4	32.0452
Maleic acid	C4H4O4	116.072
Dichloromethane	CH2Cl2	84.93
Potassium chromate	CrK2O4	194.189
Zinc sulfate	ZnSO4	161.436
Aluminum	Al	26.982
Perchloric acid	HClO4	100.46
Potassium Bromide	KBr	119.002
Chromic acid	H2CrO4	118.01
Methyl acetate	C3H6O2	74.079
Hexane	C6H14	86.18
Manganese dioxide	MnO2	86.9368
Lactic acid	C3H6O3	90.078
Lithium hydroxide	LiOH	23.95
Phosphorus pentachloride	PCl5	208.24
Potassium oxide	K2O	94.2
Monopotassium phosphate	KH2PO4	136.084
Sodium fluoride	NaF	41.98817
Sodium nitrite	NaNO2	68.9953
Barium carbonate	BaCO3	197.34
Calcium Iodide	CaI2	293.887
Lithium oxide	Li2O	29.88
Potassium Permanganate	KMnO4	158.034
Silver phosphate	Ag3PO4	418.58
Ammonium bromide	NH4Br	97.943
Calcium phosphate	Ca3(PO4)2	310.18
Ammonium carbonate	(NH4)2CO3	96.086
Barium chloride	BaCl2	208.23
Magnesium iodide	MgI2	278.1139
Ozone	O3	48
Potassium cyanide	KCN	65.12
Silver oxide	Ag2O	231.735
Sodium chromate	Na2CrO4	161.97
Sodium peroxide	Na2O2	77.98
Zinc carbonate	ZnCO3	125.388
Zinc phosphate	Zn3(PO4)2	386.11
Zinc sulfide	ZnS	97.474
Boric acid	H3BO3	61.83
Potassium bicarbonate	KHCO3	100.114
Potassium hypochlorite	KClO	90.55
Potassium nitrite	KNO2	85.103
Ammonium iodide	NH4I	144.94
Ammonium nitrite	NH4NO2	64.06
Ammonium oxide	(NH4)2O	52.0763
Barium bromide	BaBr2	297.14
Barium iodide	BaI2	391.136
Dinitrogen trioxide	N2O3	76.01
Ethylene glycol	C2H6O2	62.07
Nickel sulfate	NiSO4	154.75
Lithium chloride	LiCl	42.394
Potassium fluoride	KF	58.0967
Potassium sulfite	K2SO3	158.26
Silver carbonate	Ag2CO3	275.7453
Sodium cyanide	NaCN	49.0072
Sodium nitride	Na3N	82.976
Strontium chloride	SrCl2	158.52
Urea	CH4N2O	‎60.056
Bleach	NaClO	‎74.439
Lithium bromide	LiBr	86.844
Aluminium fluoride	AlF3	83.9767
Barium fluoride	BaF2	175.34
Copper (II) carbonate	CuCO3	123.55
Fluorine	F	18.998403
Lithium phosphate	Li3PO4	115.79
Lead Iodide	PbI2	461.01
Lithium iodide	LiI	133.844
Magnesium oxide	MgO	40.3044
Sodium dichromate	Na2Cr2O7	261.97l
Tartaric acid	C4H6O6	150.087
Zinc iodide	ZnI2	319.22
Bromine	Br	54.9380
Aluminum bromide	AlBr3	266.69
Sodium Percarbonate	C2H6Na4O12	157.01
Nickel acetate	C4H6O4Ni	178.797
Acetaldehyde	C2H4O	44.05
Copper sulfate	CuSO4	159.609
Calcium Chloride	CaCl2	110.98
Sodium Chlorate	NaClO3	106.44
Potassium Iodate	KIO3	214.001
Lead Acetate	Pb(C2H3O2)2	325.29
Formaldehyde	CH2O	30.031
Formic Acid	HCOOH	46.03
Sulfur Hexafluoride	SF6	146.06
Ethane	C2H6	30.07
Dinitrogen Pentoxide	N2O5	30.07
Phosphorous Acid	H3PO3	82
Aluminium hydroxide	Al(OH)3	78.00
Potassium acetate	CH3CO2K	98.142
Barium oxide	BaO	153.326
Copper(I) Oxide	Cu2O	143.09
Copper Hydroxide	Cu(OH)2	97.561
Ethylene	C2H4	28.054
Acetylene	C2H2	26.038
Chromic Oxide	Cr2O3	151.9904
Sodium bisulfate	NaHSO4	120.06
Copper (II) chloride	CuCl2	134.45
Mercuric chloride	HgCl2	271.52
Tin (II) chloride	SnCl2	189.60
Propane	C3H8	44.097
Lead (IV) oxide	PbO2	239.1988

FAQs on Chemical Formula

Define Chemical Formula?

The term chemical formula is used to define the chemical composition of any compound. It tells us about the elements a compound has, it also tells us about the ratio in which these elements combine.

What is Chemical Formula of Ozone?

Chemical formula of ozone is O₃. In ozone three oxygen atoms are combined with each other.

What is Chemical Formula of Rust?

Chemical formula of rust is Fe₂O₃. Its scientific name is Ferric Oxide.

What is Chemical Formula of Baking Soda?

Chemical formula of baking soda is NaHCO_3. Its scientific name is sodium bicarbonate.

What is Chemical Formula of Bleaching Powder?

Chemical formula of bleaching powder is CaOCl₂. Its scientific name is calcium oxychloride.

What is Chemical Formula of Washing Soda?

Chemical formula of washing soda is NaCO₃. Its scientific name is sodium carbonate.

What is Chemical Formula of Calcium Carbonate?

Chemical formula of calcium carbonate is CaCO₃. The common name of calcium carbonate is Chalk.