Roughly, let me remind you about all those terms learned back in our school days, like - matter is neither created nor can be destroyed, it simply transforms from one form to another and group of laws like that. We had also learned, that these laws are a part of the group of physical properties of mass, energy and matter and are fundamentals for students of chemistry, physics and general sciences. OK! I can see some downright nodding out there. Well, if you were baffling to meet its understanding potential, probably they were either formulated before you in the most complex sense, or possibly you never paid much attention to them (wink)! Let me generalize it for you in a less complex form. What is the Law of Conservation of Mass Earlier in the mid 17th century, Mikhail Lomonosov first initiated the ideas on this law and introduced chemistry to the real world of science. Later, in the year 1789, the principle of this law was first delineated by a French scientist, Antoine Lavoisier - an initiator of modern physics. The law was formerly known as matter conservation or principle of mass. Now the reason stated in this form is explained considerably by two statements:

1. Consider a complete isolated system (closed system). The mass of such a system will remain constant over a period of time. There are certain processes taking place inside a system, and thus that makes the mass of a closed system to remain stagnant or unchanged.
2. No system in nature exists that is completely closed or isolated from the external environment. Therefore, the mass of a system can neither be created nor can it be destroyed. There is only a possibility of changing it into different kinds of particles or transferring it in several forms of heat and light, or can simply be rearranged into space.

Thus, the law applies to certain chemical changes. According to the description stated above, we can define the law in a simple sentence: "During any chemical or physical change; the total mass of all the reactants in the chemical reaction is equal to the total mass of products in the same reaction." Now for instance, consider this equation of mercuric oxide: Mercury + Oxygen -----> Mercuric Oxide 92.6g + 7.4g -----> 100g Every single atom of mercury and oxygen, which is present at the start of the reaction is still accurately present at the end of the reaction, in the form of mercuric oxide composition. Hence the above law equation gets adequately justified. Since, we have stated the equation and law, let's run through the statements made in the above content based on the energy by putting it up in a decent definition. The Law of Conservation of Energy: "During a chemical reaction; the total amount of energy in the system remains unchanged. It implies that energy can neither be created nor be destroyed, but can be transferred from one form into another." Hence from all the laws stated above, one thing is very clear that, The total quantity of matter and energy which is available in the entire universe, is in a fixed amount and can never vary by more or less. This was the part where Albert Einstein played a revolutionary role in the field of chemistry and overall science. He was the man who docked the discovery of the equation E=mc² and consequently merged both of these laws in his 'Theory of Relativity', which entirely changed the definition of the law. He made it possible to show that matter and energy can be transformed from one form into another. Subsequently, today, those two separate laws are known as The Law of Conservation of Mass-Energy'. The conversion of one single type of matter into another form has always been followed with the conversion of one form of energy into another form. It is true that not all the transformations of energy involve a chemical change. The transformations can be from electrical change into mechanical energy, etc. In these changes, chemical changes are not necessarily always present. In our day-to-day lives, we see these transformations happening very often, but they are so minuscule that we generally do not pay much attention to the details. There are many other laws besides these two, like; the Law of Conservation of Parity, Constant Proportion, Momentum, etc. All these laws play a crucial role in the unison of the physical sciences and densely explicate the various properties of energy and movement.