Chemistry Formulas

The branch of science dealing with the chemical as well as physical properties of substances in a manner that further results in the formation of new substances is known as Chemistry. All elements of nature that so far exist have a specific name that has been derived through the studies of chemistry. The formulas of Chemistry are known as the chemical formulas.

A chemical formula is a way through which scientists represent the chemical proportions such as the number of atoms present in a molecule or a chemical compound. It is done with the help of chemical elements, their symbols and the numerical subscripts. The chemistry formulas can be understood through the chemistry formula table.

Types of Chemistry Formulae or Chemical Formulae

There are three types of chemical formulae:

• Molecular Formula
• Empirical Formula
• Structural Formula

Molecular Formula: Molecular formula also known as true formula provides us with the exact number of atoms of every element present in a molecule. The numerical subscripts after the chemical symbols denote the total number of atoms present. The molecular formula also tells us about the type of atom present in a molecule of a compound. Below is an example of a molecular formula.

Molecular Formula of glucose: C₆H₁₂O₆ 

It represents the actual number of atoms of each constituent (Carbon, Hydrogen and Oxygen) in one molecule of glucose.

Empirical Formula: The word empirical represents something that can be assessed through observation. As such the empirical formula which is more than often emanated from experimental data is defined as the simplest ratio of all the atoms present in the elements that make up a compound. An example of empirical formula extracted by simplifying the molecular formula of glucose:

Empirical formula of glucose: CH₂O

It represents the whole ratio number of the atoms present that is, C, H and O

Structural Formula: While it is good to have chemical formulas in an easy and compact manner, it is also important to know the arrangements of atoms in them. The structural formula tells us about atomic bonding and their arrangement in spaces. It helps us to identify which atoms are bonded with one another and which are not. Given below is an example of the structural formula of glucose which represents the atomic bonding and arrangement.

How to Write Chemical Formulas?

A chemical formula can be written by the name of the elements that constitute a compound along with some basic rules and in a reverse manner.

1. Chemical formulas of binary compounds which are made of two different elements can be written with the help of valency.
2. The capacity of the combination of the elements to form a compound or compound is known as valency. 
3. Firstly the valencies of the two elements should be determined and then the sums of the valencies of the two different elements should be made equal by specifying the common lowest multiple of the two valencies. 
4. Cation is an atom with positive charge and anion is an atom with a negative charge. In case if a metal and non-metal are present, the metal should be placed first in the formula. For example NaCl, in which Na has a positive charge and Cl has a negative charge.

Let’s take an example of balanced 

Aluminium oxide:

O = 2 (belongs to group VI)

Al = 3 (belongs to group III)

Lowest common multiple of the valencies is 6,

O : 2 x 3 = 6

Al : 3x 2 = 6

The chemical formula of Aluminium oxide is Al₂O₃

Steps to Write a Chemical Reaction

It is important to note that balancing of chemical equations plays a major role in this process.  Basically, four rules are followed while writing a chemical equation. Let’s have a look below, 

1. On the left side of the equation, the right number of reactants is written.
2. On the right side of the equation, the right formulas constituting the products are written.
3. Both the reactants and the products are partitioned by an arrow which points towards the products. This arrow indicates “to produce”.
4. With the help of plus signs various products and reactants are separated. The plus sign indicates ” reacts with” on the reactants side and it means “and”  on the products side.

Let’s take an example of a balanced chemical reaction where hydrogen and chlorine will react to make HCl.

The first step involves writing the equation in terms of the formulas of both the elements, both of which are diatomic in nature.

H2 + Cl2 → HCl 

There are two hydrogen atoms and chlorine atoms on the reactants side and one atom each on the product which can be now fixed and balanced by the inclusion of the coefficient 2 on the side of the product.

H2 + Cl2 → 2HCl

Now both the sides are balanced having two hydrogen and chlorine atoms each.

Some examples of chemical reactions are listed below:

Photosynthesis: 6CO2 + 6H2O  → C6H12O6 + 6O2 + 6H2O

Calcium carbonate formation: CaCl2 + Na2CO3 → CaCO3 + 2NaCl

Iron rusting: 4Fe + 3O2 + 6H2O → 4Fe(OH)3.

Combustion of hydrogen: 2H2(g) + O2(g) → 2H2O(l ) 

Table of Chemical Formulas (Molecular)

List of Chemical Compound Formulas

Compounds are basically substances that constitute two elements or more in a definite percentage. With the help of chemical formulas, the atoms of the elements in a compound can be known. The list below shows some chemical compounds along with their chemical formulas.