The word isotopes are the combination of two words, one is Iso which means ''same', and another is topes which means ''places'' those elements which have the same atomic number (numbers or proton), but different mass number are called isotopes. In a neutral atom there is equal numbers of proton and electron, so their chemical properties are same but have different physical properties, so we can separate them by physical method. Usually, mass spectrograph is the method which is used to separate the isotopes of different elements.