When you look around you notice the clothes you are wearing, furniture, people and arrangements that are the most immediate objects in your direct view. Looking outside the window you may observe the earth, clouds, vehicles, the sun, or the moon. The stars and galaxies, making up the universe are observed at night as distant objects. The objects that make up our universe contain matter. Matter is anything that occupies space and has mass. Chemistry is the study of the composition of matter and its transformation.

All matter is composed of elements since they act as the building blocks of nature. Based on their chemical properties the periodic table, a succinct map classifies chemical elements into columns or groups and rows or periods. Presently, there are 118 known chemical elements, with whole numbers 1 to 118. The numbers are denoted as the element’s atomic number and give the number of protons in the nucleus of an atom of the element.

A symbolic representation of a chemical reaction is called a chemical equation. The left and the right side consist of reactant, chemical(s) and product chemical(s) and the number of atoms present in the reactants has to balance the number of atoms present in the products. The bottom line is you balance the equations by sticking numbers in front of the chemicals on both the left and right sides of the equation, like it or not.
  • Write down your given equation or unbalanced equation
  • Draw boxes around all the chemical formulas and make an element inventory
  • On each side of the equation, write down the number of atoms per each element that is given
  • Find the number of atoms in the equation looking at the subscripts next to each atom
  • Leave hydrogen and oxygen for last always
  • If you have more than one element left to balance, balance the carbon atoms first.
  • Add a coefficient to the single carbon atom on the right of the equation to balance it with the carbon atoms on the left of the equation.
  • Balance the hydrogen atoms and then the oxygen atoms
  • The carbon, hydrogen, and oxygen atoms are balanced.
  • Your equation is complete.

What is a Balanced Equation? 
A chemical equation is balanced when the number of atoms of every type on every side of the equation is equal.
For example, the chemical formula for water is H$_2$O indicates that 2 atoms of Hydrogen combines with 1 atom of oxygen. The formula for magnesium bromide MgBr$_2$ indicates that one magnesium atom combines with two bromine atoms in a one-to-two ratio. Similarly the chemical formula for sodium chloride (Salt) is NaCl indicates that one atom of sodium combines with one atom of chlorine in a one-to-one ratio.

Remember the Don'ts while Balancing a Chemical Equation
  • You never make half of a molecule or half atoms in a chemical reaction hence never use fractions as coefficients in a chemical equation
  • Multiply the entire equation (both the left and right sides) by the number in the denominator of your fraction to get rid of fractions.
  • You may use fractions to assist you, during the balancing process, but the equation remains unbalanced as long as there are coefficients using fractions.
The following list of Chemical Formula and Equations are some of the most common chemical formulas.

$CO_2$             Carbon Dioxide             
HCl
 Hydrochloric Acid
$H_2$O Water
 NaCl  Salt
 $C_2H_6O$ Ethanol
 $NH_3 $ Ammonia
 $C_4H_{10}$ Butane
 $H_2SO_4$Sulfuric Acid 
$CH_4$Methane
 $NaHCO_3$ Baking Soda
 $CuSO_4$ Copper Sulfate
             $C_nH_{2n}O_n$             Sugar
 $Au_2S$ Gold Sulfide
$C_6H_{12}O_6$ Glucose
 $NO_{3}^{-}$ Nitrate
 $Zn(NO_3)_2$ Zinc