Chemical Formula - Overview, Importance, Types, List, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:27 PM IST

Chemistry is a field of science that studies the physical and chemical characteristics of substances, as well as their composition and use in the creation of new ones. Every element that occurs in nature and is known to us has been given a distinct name and a one or two letter symbol in order to make them useful for our own use in chemistry. The majority of the elements' names are drawn from English, although their symbols are derived from either their English names or their Latin names.

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Importance of Science Chemical formula
Types of Chemical formula in Science
Empirical Formula
Structural Formula
Projection Formula
How to write a chemical formula
Chemical formula of Organic Compounds
Chemical formula table:

Chemical Formula - Overview, Importance, Types, List, FAQs

Chemical formulas allow you to express any chemical compound using the symbols for the components that make it up. All chemical formulas reveal the components that make up a compound's molecules, as well as the proportions in which these elements' atoms mix to create those molecules. The molecular formula H₂O, for example, indicates that two hydrogen atoms unite with one oxygen atom to produce one water molecule. Similarly, sulfuric acid has the chemical formula H₂SO₄, indicating that the proportions of H, S, and O in this molecule are 2:1:4.

So, in chemistry, all chemical formula is a shorthand representation of the components of a molecule, using the unique symbols given to each element in the periodic table.

Importance of Science Chemical formula

Chemical formulas give information about a compound's chemical composition.
They also show how the individual elements mix to produce the compound.
Chemical formula is crucial for students and professionals to predict, explain, and analyze chemical phenomena.
Ions, free radicals, and other chemical species can also be represented using chemical formulas.
Aid in producing chemicals, pharmaceuticals, and other products by specifying the exact formulation required.
Provide insights into the molecular structure and properties of substances.

Types of Chemical formula in Science

Any of numerous types of expressions of the composition or structure of chemical compounds is referred to as a science chemical formula. The term "chemical formula" usually refers to a compound's molecular formula (which denotes the total number of atoms of each constituent element in one molecule of the compound). Empirical, molecular, structural, and projection formulae are the other types.

Molecular Formula: The number of components in a molecule may be determined using the molecular formula. The elements are designated by their respective symbols (as in the periodic table) in molecular formulas, and the number of atoms of each element in the molecule is written in subscript. The chemical formula for glucose, for example, is C₆H₁₂O₆.
Empirical Formula: The ratio of the elements contained in a chemical compound is represented by the empirical formula. The majority of empirical formulas are derived through the examination of experimental data. CH₂O is the empirical formula for glucose. The molecular formulas can be used to create empirical formulae.
Structural Formula: The structural formula of a chemical compound, as the name implies, reveals the atoms' arrangement in the molecule.

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Empirical Formula

Ordinarily, empirical formulae are used to describe compounds with unknown molecular structures or chemicals that are not made up of common molecular entities, such as sodium chloride (table salt), which is made up of ions. A molecular formula is used to indicate the chemical makeup of a substance's constituent molecules (the molecule being the smallest unit in which the substance keeps its chemical characteristics).

As a result, benzene is represented by the empirical formula CH, indicating that a typical sample includes one atom of carbon (C) and one atom of hydrogen (H) (H). Water is represented by the empirical formula H₂O, which indicates that it contains two hydrogen (H₂) atoms for every atom of oxygen (O)

The chemical formula C₂H₄ and C₃H₆ for ethylene and propylene, for example, specify the number and type of atoms contained in each substance's molecule. Ethylene and propylene, on the other hand, have the same empirical formula, CH₂, since they are both made up of carbon and hydrogen atoms in a 1:2 ratio. The empirical and molecular formulae of a material may be similar in some situations, such as water.

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Structural Formula

Chemical bonds between atoms in a molecule are identified by structural formulae. A structural formula is made up of atom symbols linked by short lines that indicate chemical bonds—single, double, or triple bonds are represented by one, two, or three lines, respectively. The structural formula of ethane, for example, is

Ethane

indicating that the molecule is made up of two carbon atoms, each connected to the other by a single bond, and three hydrogen atoms. Structural formulae are especially effective for demonstrating the differences between compounds of the same type and number of atoms.

Projection Formula

A projection formula is a two-dimensional depiction of a three-dimensional molecule that is truly two-dimensional. This sort of formula is similar to the structural type in that it is made up of symbols that represent atoms of the component elements linked by dashes or curves that represent chemical bonds. Thus, the projection formula neatly represents the methane molecule, which is defined by a tetrahedral arrangement of four chemical bonds around a carbon atom.

Methane

Stereoisomers are substances that have the same composition but differ in the spatial arrangement of the atoms that make up their molecules. Projection formulae are frequently employed in the study of stereoisomers. Stereoisomers can be recognised from one another by suitable variations in their formulae, thanks to certain standards for drafting projection formulas.

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How to write a chemical formula

To create a chemical formula, we need to know the symbol for the elements in the compound, the radicals formula, and the valency of the elements in the compound. When constructing a chemical formula, keep the following considerations in mind.

The majority of the compounds are binary, meaning they only include two components. There are other compounds containing more than two elements.
A cation is an atom with a positive charge, while an anion is an atom with a negative charge.
The metal is named first, followed by the non-metal, in a combination comprising both metal and non-metal. For instance, NaCl is made up of Na⁺ (metal ion) and Cl^– (chloride ion) (non-metal ion)
Anions with a -1 negative charge are generally suffixed with –ide. F⁻ - Floride, for example.
Anions with oxyanions (oxygen + another element) are generally suffixed with –ate. For instance, SO₄^2- (Sulphate)
Bi- or hydrogen is used as a suffix when a polyatomic anion has H– ion. HCO₃^-Bicarbonate or hydrogen carbonate are two examples.
Following are some examples of polyatomic anions:

Polyatomic Anion	Basic Chemistry Formula
Phosphate	PO₄^3-
Cyanide	CN^-
Amide	NH₂^-
Nitrate	NO₃^-

Chemical formula of Organic Compounds

Organic compounds are made up of a mixture of carbon and hydrogen, as well as nitrogen and a few additional elements including phosphorus, sulphur, silicon, and the halogens. The majority of organic chemicals are biologically derived, since they are present in nature.

Hydrocarbon: Hydrocarbons are substances made up entirely of carbon and hydrogen. Alkanes are hydrocarbons that have just single bonds between them. Methane is the most basic example (shown below). Ethene (C₂H₄) is the most basic alkene, with a double bond between the two carbon atoms.

Eg: Methane, Ethane

Functional Group: Atoms linked to carbon chains or rings of organic compounds form functional groups. Within a functional group, compounds tend to have similar qualities and characteristics. Hydroxyl and carboxyl groups are two typical functional groups. Alcohols are hydroxyl groups that terminate in -OH. Compounds having -COOH carboxylic acids have carboxyl groups that terminate in -COOH. Prefixes are used by functional groups to assist name compounds with comparable chemical characteristics, which helps with nomenclature.

Eg: Hydroxyl group. Carboxyl group

Chemical formula table:

Some of the chemical formula example listed below as compound names and formulas.

Common Acids

Name	Chemistry Chemical formula
Acetic acid	CH₃COOH
Nitric Acid	HNO₃
Sulfuric Acid	H2SO₄
Hydrochloric Acid	HCl
Nitrous Acid	HNO₂
Sulphurous Acid	H₂SO₃
Hyposulphurous Acid	H₂SO₂
Carbonic Acid	H₂CO₃
Phosphorous Acid	H₃PO₄
Phosphoric Acid	H₃PO₄
Oxalic Acid	H₂C₂O₄
Chromic Acid	H₂CrO₄
Citric Acid	C₆H₈O₇
Formic Acid	HCOOH

2. Common Bases Chemical formula

Name	Chemical formula
Potassium Hydroxide	KOH
Lithium Hydroxide	LiOH
Calcium Hydroxide	Ca(OH)₂
Sodium Hydroxide	NaOH
Barium Hydroxide	Ba(OH)₂
Arsenic Hydroxide	As(OH)₃
Aluminium Hydroxide	Al(OH)₃
Ammonium Hydroxide	NH₄OH
Mercury(I) Hydroxide	Hg₂(OH)₂
Mercury(II) Hydroxide	Hg(OH)₂
Led (IV) Hydroxide	Pb(OH)₄
Tin (II) Hydroxide	Sn(OH)₂

Common Cations & Anions

Cations	Formula	Anions	Formula
Ammonium	NH₄⁺	Acetate	CH₃COO^-
Calcium	Ca²⁺	Chloride	Cl^-
Copper	Cu²⁺	Fluride	F^-
Potassium	K⁺	Nitrite	NO^2-
Iron	Fe²⁺, Fe³⁺	Nitrate	NO^3-
Sodium	Na⁺	Oxide	O^2-
Led	Pb²⁺	Sulfate	SO₄^2-

Most Important Ones

Chemical Compound	Chemical formula of Compounds
Aluminium Acetate	C₆H₉AlO₆
Aluminium Bromide	AlBr₃
Aluminium Carbonate	Al(CO₃)₃
Aluminium Iodide	AlI₃
Aluminium Oxide	Al₂O₃
Aluminium	Al
Ammonia	NH₃
Ammonium dichromate	Cr₂H₈N₂O₇
Ammonium bicarbonate	NH₄HCO₃
Ammonium acetate	C2H3O2NH4
Ammonium carbonate	(NH₄)₂CO₃
Ammonium nitrate	NH₄NO₃
Ammonium oxide	(NH₄)₂O
Benzene	C₆H₆
Benzoic Acid	C₇H₆O₂
Potassium bromate	KBrO₃
Butane	C₄H₁₀
Calcium Acetate	C₄H₆CaO₄
Calcium Hydroxide	Ca(OH)₂
Calcium nitrate	Ca(NO₃)₂
Carbon Tetrachloride	CCl₄
Chromic Acid	H₂CrO₄
Iron oxide	Fe₂O₃
Carbon monoxide	CO
Glycerol	C₃H₈O₃

The above table shows chemical formulas List.

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Frequently Asked Questions (FAQs)

1. Give chemical names and formulas iron and chlorine.

Iron – Fe, Chlorine – Cl

2. Write the molecular formula of water.

H₂O

3. What is the significance of chemical formula?

Chemical formulas are important to understanding the composition, structure, and reactions of substances. They simplify complex chemical concepts and aid in scientific communication.

4. What is a chemical formula?

A chemical formula is a symbolic representation of a substance, indicating the types and number of atoms or ions in a molecule or compound.

5. What is a chemical formula?

A chemical formula is a concise way to represent the types and numbers of atoms in a chemical substance using chemical symbols and numbers. It provides essential information about the composition of a compound or molecule.

6. What is the difference between empirical formula and molecular formula?

An empirical formula shows the simplest whole-number ratio of elements, while a molecular formula indicates the actual number of atoms in a molecule.

7. What's the difference between organic and inorganic compound formulas?

Organic compound formulas typically contain carbon and hydrogen, often with other elements like oxygen or nitrogen. They often use condensed or structural formulas to show bonding. Inorganic compound formulas usually don't contain carbon (with some exceptions) and are often represented by simpler empirical formulas.

8. What's the difference between a condensed formula and a molecular formula?

A condensed formula shows the arrangement of atoms in a molecule using a more compact notation, often grouping repeated units. For example, the condensed formula CH3CH2OH represents the same molecule as the molecular formula C2H6O (ethanol).

9. What are the limitations of chemical formulas?

Chemical formulas don't show the three-dimensional structure of molecules, the types of bonds between atoms, or the arrangement of atoms in space. They also don't provide information about a substance's physical or chemical properties beyond its composition.

10. What's the significance of coefficients in chemical equations versus subscripts in formulas?

Coefficients in chemical equations indicate the number of molecules or formula units, while subscripts in formulas show the number of atoms within a single molecule or formula unit. Changing coefficients changes the amount of substance, while changing subscripts changes the substance itself.

11. How do you determine the oxidation states of elements in a compound from its formula?

Oxidation states can be determined by assigning known oxidation states to certain elements (like O usually being -2) and then balancing the overall charge of the compound to zero. This process often requires knowledge of common oxidation states and compound types.

12. What does a dot (·) mean in a chemical formula like CaSO4·2H2O?

A dot in a chemical formula indicates a hydrate, where water molecules are incorporated into the crystal structure of a compound. In this case, it represents calcium sulfate dihydrate, with two water molecules per CaSO4 unit.

13. How do you calculate the molar mass of a compound from its formula?

To calculate molar mass, sum the atomic masses of all atoms in the formula. For example, for H2O: (2 × mass of H) + (1 × mass of O) = (2 × 1.008 g/mol) + (1 × 16.00 g/mol) = 18.02 g/mol.

14. How do chemical formulas relate to the periodic table?

Chemical formulas use symbols from the periodic table to represent elements. The arrangement of elements in the periodic table can often predict the formulas of compounds they form, especially for main group elements.

15. What's the significance of brackets in formulas like [Cu(NH3)4]SO4?

Brackets in complex ion formulas indicate a group of atoms that act as a single unit. In this case, [Cu(NH3)4]2+ is a complex ion consisting of a copper ion bonded to four ammonia molecules, paired with a sulfate ion.

16. How do you write the formula for an ionic compound?

To write an ionic compound formula, balance the positive and negative charges of the ions involved. The subscripts in the formula should represent the smallest whole-number ratio that achieves charge neutrality.

17. What's the difference between empirical and molecular formulas?

An empirical formula shows the simplest whole-number ratio of atoms in a compound, while a molecular formula gives the actual number of atoms of each element in a molecule. For example, the empirical formula of glucose is CH2O, but its molecular formula is C6H12O6.

18. How do you determine the empirical formula of a compound?

To determine the empirical formula, you need to find the molar ratios of elements in the compound. This involves dividing the mass or moles of each element by its atomic mass, then reducing these ratios to the smallest whole numbers.

19. How do you determine the formula of a compound from its percent composition?

To find the formula from percent composition, convert the percentages to masses, then to moles, and finally to a ratio of moles. This ratio, when reduced to whole numbers, gives the empirical formula. If the molecular mass is known, you can determine the molecular formula from there.

20. How do chemical formulas relate to the law of constant composition?

The law of constant composition states that a pure compound always contains the same elements in the same proportion by mass. Chemical formulas directly represent this law by showing the fixed ratio of atoms in a compound.

21. What does a fractional subscript in a formula like Fe0.95O mean?

Fractional subscripts in formulas, often seen in non-stoichiometric compounds, indicate an average composition. In this case, Fe0.95O suggests that for every oxygen atom, there are on average 0.95 iron atoms, implying some iron vacancies in the crystal structure.

22. What does a subscript in a chemical formula represent?

A subscript in a chemical formula represents the number of atoms of the element immediately preceding it. For example, in H2O, the subscript 2 indicates there are two hydrogen atoms for every oxygen atom.

23. How do chemical formulas help in balancing equations?

Chemical formulas are essential for balancing equations as they provide the exact number of atoms of each element on both sides of the equation. This allows us to ensure that mass is conserved during chemical reactions.

24. What's the difference between covalent and ionic compound formulas?

Covalent compound formulas typically represent discrete molecules (like H2O or CO2), while ionic compound formulas represent the ratio of ions in the crystal lattice (like NaCl or CaCl2). Ionic formulas are always empirical formulas.

25. How do you read a chemical formula like Ca(NO3)2?

This formula is read as "calcium nitrate." It contains one calcium atom and two nitrate groups. The parentheses indicate that the NO3 group is repeated twice, so there are two nitrogen atoms and six oxygen atoms in total.

26. How do you determine the charge of polyatomic ions from their formulas?

The charge of a polyatomic ion can be determined by comparing its formula to that of a known compound. For example, in (NH4)2SO4, we know SO4 has a 2- charge, so NH4 must have a 1+ charge to balance it.

27. Why are chemical formulas important in chemistry?

Chemical formulas are crucial in chemistry because they allow us to communicate the exact composition of substances, calculate molecular masses, determine stoichiometric relationships in reactions, and predict chemical properties based on the elements present.

28. How do chemical formulas relate to the concept of stoichiometry?

Chemical formulas are fundamental to stoichiometry as they provide the exact ratios of elements in compounds. This information is crucial for calculating the quantities of reactants and products in chemical reactions, as well as for determining limiting reagents and theoretical yields.

29. How do chemical formulas relate to the concept of mole and Avogadro's number?

Chemical formulas allow us to connect the microscopic world of atoms and molecules to the macroscopic world of measurable quantities. One mole of any substance contains Avogadro's number (6.022 × 10^23) of formula units, whether they are atoms, molecules, or ionic compounds. This relationship is fundamental for quantitative chemistry calculations.

30. What's the significance of using superscripts in chemical formulas?

Superscripts in chemical formulas typically indicate the charge of an ion. For example, Ca2+ represents a calcium ion with a +2 charge, while SO42- represents a sulfate ion with a -2 charge. In nuclear chemistry, superscripts may also indicate the mass number of an isotope.

31. What's the significance of using Greek letters in some chemical formulas?

Greek letters in chemical formulas often indicate specific structural features or isomers. For example, α-glucose and β-glucose are isomers that differ in the orientation of a hydroxyl group. In organic chemistry, Greek letters may also indicate the position of substituents relative to a functional group.

32. What's the significance of using line-angle formulas in organic chemistry?

Line-angle formulas simplify the representation of organic molecules by omitting carbon and hydrogen atoms. Each vertex and line end represents a carbon atom with its associated hydrogens. This notation makes it easier to visualize the carbon skeleton and functional groups of complex molecules.

33. How do you write the formula for a zwitterion?

A zwitterion formula shows both positive and negative charges within the same molecule. For example, the amino acid glycine in its zwitterionic form is written as H3N+CH2COO-, indicating a positively charged amino group and a negatively charged carboxyl group.

34. How do chemical formulas relate to the concept of oxidation numbers?

Chemical formulas can be used to determine and represent oxidation numbers of elements in compounds. By assigning known oxidation numbers to certain elements and balancing the overall charge, you can deduce the oxidation states of other elements in the compound.

35. How do you determine the formula of a compound from its mass spectrum?

Mass spectrometry provides the molecular mass and fragmentation pattern of a compound. The molecular ion peak gives the molecular mass, which can be used to determine the molecular formula. The fragmentation pattern can provide additional information about the structure.

36. What's the significance of structural formulas?

Structural formulas show how atoms are arranged and bonded within a molecule. They provide more detailed information about molecular geometry and bonding patterns, which is crucial for understanding chemical properties and reactivity.

37. What's the difference between structural isomers and their formulas?

Structural isomers have the same molecular formula but different structural formulas. For example, C4H10 could represent both butane (CH3CH2CH2CH3) and isobutane ((CH3)3CH), which have different properties despite the same atomic composition.

38. What's the difference between empirical, molecular, and structural formulas in terms of information provided?

Empirical formulas provide the simplest whole-number ratio of atoms. Molecular formulas give the actual number of each type of atom in a molecule. Structural formulas show how the atoms are arranged and bonded within the molecule, providing the most detailed information.

39. What does a formula like NaHCO3 tell us about the compound's acidity?

The formula NaHCO3 (sodium bicarbonate) indicates that the compound contains a hydrogen atom that can be donated as a proton, suggesting it has acidic properties. The presence of both Na+ and HCO3- ions also indicates it's a salt of a weak acid (carbonic acid) and a strong base (sodium hydroxide).

40. How do you write the formula for a radical species?

Radical species are typically denoted by a dot (·) next to the chemical formula to represent the unpaired electron. For example, the methyl radical is written as ·CH3 or CH3·.

41. What does a formula like K4[Fe(CN)6] tell us about the compound's structure?

This formula represents potassium ferrocyanide. It indicates that the compound contains four potassium ions and a complex anion [Fe(CN)6]4-. The iron is coordinated to six cyanide ligands, forming an octahedral complex.

42. How do you write the formula for a coordination compound?

Coordination compound formulas typically show the metal ion in square brackets, followed by its ligands. The overall charge of the complex is written as a superscript outside the brackets. For example, [Co(NH3)6]Cl3 represents a cobalt(III) complex with six ammonia ligands and three chloride counterions.

43. What does a formula like C6H5COOH tell us about the compound's functional groups?

This formula represents benzoic acid. The C6H5 part indicates a benzene ring, while the COOH group represents a carboxylic acid functional group. This condensed formula provides information about both the carbon skeleton and the presence of specific functional groups.

44. What does a formula like CH3CH=CHCH3 tell us about the compound's bonding?

This formula represents 2-butene. The presence of "=" indicates a double bond between the second and third carbon atoms. This information about bonding is crucial for understanding the compound's reactivity and physical properties.

45. How do you write the formula for an allotrope?

Allotropes are different structural forms of the same element. Their formulas often use subscripts or structural representations to differentiate them. For example, O2 represents molecular oxygen, while O3 represents ozone. For carbon, graphite and diamond are both represented as C, but their structures are described differently.

46. How do you write the formula for a hydrate?

Hydrate formulas are written with the anhydrous compound formula followed by a centered dot and then the number of water molecules. For example, CuSO4·5H2O represents copper(II) sulfate pentahydrate.

47. What does the prefix "mono-", "di-", "tri-" etc., mean in chemical formulas?

These prefixes indicate the number of atoms of a particular element in a molecule. For example, in carbon monoxide (CO), "mono-" indicates one oxygen atom, while in carbon dioxide (CO2), "di-" indicates two oxygen atoms.

48. How do you determine the formula of a gas from its density and molar mass?

If you know the density of a gas and its molar mass, you can determine its molecular formula. The molar mass divided by the density (in g/L) at STP should equal 22.4 L/mol (the molar volume of an ideal gas). This gives you the number of gas particles per formula unit.

49. What's the significance of the Hill system in writing organic formulas?

The Hill system is a standardized way of writing molecular formulas for organic compounds. It lists carbon first, followed by hydrogen, and then all other elements in alphabetical order. This system ensures consistency in chemical databases and literature.

50. How do you write the formula for a mixed crystal or solid solution?

Mixed crystals or solid solutions are often represented by formulas with parentheses and comma-separated elements. For example, (Mg,Fe)2SiO4 represents olivine, where magnesium and iron can substitute for each other in varying proportions.

51. How do you write the formula for a polymer?

Polymer formulas often use parentheses with a subscript n to indicate repeating units. For example, (C2H4)n represents polyethylene, where the ethylene monomer (C2H4) is repeated n times. For more complex polymers, the repeating unit is enclosed in square brackets with a subscript n.

52. How do you determine the formula of a compound from its crystal structure?

The formula of a compound can be determined from its crystal structure by analyzing the types and numbers of atoms in the unit cell, the smallest repeating unit of the crystal. The ratio of these atoms, when reduced to whole numbers, gives the empirical formula of the compound.

53. What does a formula like trans-CH3CH=CHCH3 tell us about the compound's geometry?

This formula represents trans-2-butene. The "trans-" prefix indicates that the methyl groups (CH3) are on opposite sides of the carbon-carbon double bond. This geometric information is crucial for understanding the compound's properties and reactivity.

54. How do you write the formula for a coordination polymer?

Coordination polymer formulas typically show the repeating unit in square brackets with a subscript n. For example, [Cu(CN)2]n represents a copper cyanide coordination polymer where copper ions are linked by cyanide bridges in an infinite chain.

55. What's the significance of using wedge and dash notation in chemical formulas?

Wedge and dash notation in chemical formulas provides three-dimensional information about molecular structure. A solid wedge indicates a bond coming out of the plane towards the viewer, a dashed wedge indicates a bond going behind the plane, and a straight line represents a bond in the plane of the paper.