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Chemistry Formulas

23rd Aug 2020 @ 5 min read


Understanding Chemistry Formulas

The detergent we use to wash utensils or the pills that we take for medication is made from fixed proportions of atoms. Even the sugar we put in our coffee is made up of atoms. These atoms are arranged in a specified proportion to get the desired compound or substance. To know these proportions, the chemical formula of the substance is required. Also known as a chemistry formula.

A compound comprises two or more than elements, and the chemistry formula reveals the number of atoms present in each component. The chemical formula contains symbols of the element’s atoms in the compound. It also reflects the number of atoms present in each element.


How to write Chemistry formulas?

All chemical substances have a unique chemical composition and a chemistry formula. For example, the chemical formula of Carbon Dioxide contains 1 Carbon (C) and 2 Oxygen (O2) atoms. Hence, we can write it as CO2.

Here are some key characteristics of atoms you must know before understanding chemical formulas:

● Atoms with a positive charge are termed as cat-ions, and the ones with a negative charge are termed as anions

● An ions are represented with (-) and cat-ions are represented with (+)

● If the compound contains both metal and non-metal, then metal comes first in the name of the compound. For example, NaCl has Na (Metal) and Cl (Non-Metal)

Each chemical formula gives unique information about the composition of chemical substances. Normally, there are four types of chemical formulas, including empirical, molecular, structural, and condensed structural formulas.

Let us study these in detail:

1. Molecular Formula

The molecular formula helps in identifying the number of elements in the molecule of the compound. All the elements are identified through their periodic table symbols. The number of atoms is written as a subscript.


When you look at Glucose - it is composed of 6 Carbon (C), 12 Hydrogen (H), and 6 Oxygen (O) atoms.

Glucose Formula

2. Empirical Formula

An empirical formula is always verified by observing experiments. It is defined as the simplified ratio of the element’s whole numbers that create a compound. The empirical formula is typically written by studying experimental readings in the lab.

An empirical formula can easily be simplified through fractions.

Let us again take the example of Glucose.

Its molecular formula reflects the real number of atoms present in every element of a molecule. But the empirical formula comprises the simplest ratio and not the real number of atoms.

While the molecular formula gives us the actual number of atoms of each element in a molecule, the empirical formula gives us the simplest ratio and not the actual number of atoms of an element. However, there are some molecular formulas that are identical to empirical formulas.

Here are some examples:

The molecular formula of Glucose C₆H₁₂O₆ can be reduced to CH₂O by taking the highest common factor of atoms.

molecular vs empirical

But when we observe the molecular formula of Sucrose C₁₂H₂₂O₁₁, we can’t derive the highest common factor of atoms. Hence, its empirical formula will also be the same, i.e. C₁₂H₂₂O₁₁.

3. Structural Formula

A simple molecular formula will never give an idea of the arrangement of atoms or their bonding. The structural formula is used to study the bonding of elements with each other. It reflects the arrangement of atoms, number of elements, and their bonding with each other.

Let us observe Ethanol here. In Ethanol, the first carbon atom gets bonded to three hydrogen atoms, the second carbon atom gets bonded to two hydrogen atoms, and one carbon atom on the left and the oxygen atom gets bonded to hydrogen on the right and carbon on the left.

Ethanol Formula

4. Condensed Structural Formula

The condensed structural formula is also known as a semi-structural formula. It is written in a simple line of text. It reflects all the atoms of the organic structure but doesn’t show vertical bonds or single bonds in the majority of cases.

Here are examples of Ethane (CH₃CH₃ or), Propane (CH₃CH₂CH₃), and Ethanol (CH₃CH₂OH). Their condensed structural formulas are shown in the diagram below.

Ethane Propane and Ethanol structural formula


To conclude, chemical formulas are like the shorthand of Chemistry. These formulas are the easiest way to find out the nature of chemical compounds and the way they react with each other. It also helps us understand the formation of a substance or compound while revealing the proportion of elements involved.

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Organic Chemistry Chemistry Formulas

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David C Wakefield
22nd Aug 2021
Nice overview
21st Nov 2020
07th Sep 2020
02nd Sep 2020
Great resource for learning
03rd Aug 2020
Thank you i appreciate the explanation of formulas.

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