modern atomic theory

Position of an element in the Periodic Table, its atomic number and atomic mass Periodic Table to identify metals, semimetals, nonmetals, and halogens Periodic Table to identify alkali metals, alkaline earth metals and transition metals, and trends in ionization energy, elec..

Position of an element in the Periodic Table, its atomic number and atomic mass Periodic Table to identify metals, semimetals, nonmetals, and halogens Periodic Table to identify alkali metals, alkaline earth metals and transition metals, and trends in ionization energy, elec..

Rutherford's model had a major drawback. It could not explain why ultimately electrons did not fall into the nucleus by taking a spiral path. This was in concurrence with the electromagnetic theory that states 'if a charged particle undergoes accelerated motion then it must radiate energy..

Bohr's Atomic Model - 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 electron..

To use this theory for predicting the shapes of molecules, the number of electron pairs (both, shared and lone pairs) is simply counted. This is illustrated by taking a typical molecule of the type AB n . 'A' is the central atom, 'B' atoms are bonded to 'A' by single ..

The VSEPR theory, proposed by R.J.Gillespie and R.S. Nyholmm in 1957, is based on the repulsions between the electron-pairs in the valence-shell of the atoms in the molecule. It was developed to predict the shapes of the molecules in which the atoms are bonded to..

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 century. With the advent of electricity and phenomenon of spectrum, experimentation underwent a chan..

Atomic Number (Z) is the number of protons in the nucleus of an atom. It is also equal to the number of electrons since the atom is electrically neutral. Mass Number (A) is the total number of neutrons and protons present in the nucleus of an atom. The p..

. As the radiating energy of a revolving electron (according to classical electromagnetic theory) continuously decreases the electron should follow a spiral path and fall into the nucleus. So this atomic model could not account for the stability of the atom. The observ..

According to LCAO method, the orbitals are formed by the linear combination (addition or subtraction) of atomic orbitals of the atoms, which form the molecule. This theory is applicable to hydrogen molecule as follows. Consider that hydrogen molecule consists of ..