modern atomic theory

The evidence of the electrical nature of matter preceeded the first theories about the structure of matter. In 1832, Michael Faraday discovered electrolysis. He gave the first important clue relating electricity to matter and about the electric nature of atoms..

Laws of Chemical Combination With the development of more scientific ideas on elements, compounds and mixtures, people began to probe into how and why substances react. French chemist A. Lavoisier laid the foundation to the scientific investigation of matter by describing that substances react ..

Atoms and Molecules - Summary The law of conservation of mass states that the masses of the reactants and products remain unchanged. The law of constant proportions states that all pure specimens of a compound always contain the same elements combined together in the same proportion by we..

Matter is made up of atoms and molecules. These atoms in molecules are in a state of continuous motion. For example, molecules and atoms of a solid can have only vibrational motion, because they are held in their positions by strong intermolecular force..

Under normal conditions matter exists in three forms: solid liquid gas Matter is made up of atoms and molecules. These atoms in molecules are in a state of continuous motion. For example, molecules and atoms of a solid can have only vibrational motion, because they are..

Later, Henry Gywn-Jeffreys Moseley showed that the atomic number of an element is numerically equal to the number of electrons round the nucleus. The number of electrons in turn is equal to the number of protons in the nucleus. He suggested that atomic number is a more fundamen..

Two new theories came to substantially modify Bohr's Atomic model. They a..

Although Dalton's theory of the existence of atoms was published in 1808, there was no clear idea of what an atom might look like until the early part of the twentieth centur..

In 1913, Neils Bohr proposed a model of an atom based on the Planck's quantum theory of radiation. The basic postulates of Bohr's theory are: * An atom consists of a small, heavily positively charged nucleus around which electrons revolve in defini..

Wave nature of material objects In 1924, de Broglie's suggested that all material objects including an electron have a dual character; they behave as particles as well as waves. The wavelength associated with a particle of mass 'm', moving with velocity 'v' is given by de Broglie's relation as: ..