Topic: Physical Chemistry

The law was revealed by Swiss-Russian chemist and doctor Germain Henri Hess. He introduced the law in its 1840’s publication.

The four laws are the zeroth law, the first law, the second law, and the third law. These laws are universally valid to any thermodynamic system and are described as follows:

Different types of chemical reactions.

In chemistry, our concern is not with the absolute value of enthalpy but rather the change in the enthalpy. The absolute enthalpy cannot be estimated directly since the value of the absolute internal energy cannot be reckoned for real systems. Further, in chemistry and thermodynamics, we are interested in measuring the change in enthalpy, not its absolute value.

Boyle's law is the gas law that states the pressure of an ideal gas is inversely proportional to its volume if the temperature and amount of the gas remain constant.

Dmitri Mendeleev was one of the great chemists of the 19th century. He correctly predicted the properties of more than three undiscovered elements. His contributions to chemistry won him the title of the father of the modern periodic table.

Dmitri Mendeleev's Periodic Table was the most scientific periodic table in his time, which led to the formation of the modern periodic table. Mendeleev not only group the elements that shared similar properties but also correctly predicted the properties of undiscovered elements. And this was groundbreaking.

Lothar Meyer's periodic table was a raw version of the periodic table. He successfully classified the elements according their valency with the increasing order of atomic weights. He also depicted the periodicity from his atomic volume vs atomic weight graph.

Newlands' Law of Octaves proposed by John Newlands explains the periodic repetition of physical and chemical properties. The law has many limitations, which are discussed in this article.

De Chancourtois's helical periodic table was the first periodic table that introduced the notion of the periodicity of elements.