The valence electrons for the representative (main) group of elements are found in the outermost (highest energy) s and p sublevels. They are often together called the valence shell. Electron configurations can make it easy to see the valence shells for the atoms of the elements.

In all the chemistry of the transition elements, the 4s orbital behaves as the outermost, highest energy orbital. The reversed order of the 3d and 4s orbitals only seems to apply to building the atom up in the first place.

3 subshells

The “n” and “l” in the (n + l) rule are the quantum numbers used to specify the state of a given electron orbital in an atom. n is the principal quantum number and is related to the size of the orbital. If two orbitals have the same value of (n + l), they are filled in order of increasing n.

Explanation: According to (n+l) rule: Orbital which has the least value of (n+l) will be filled first to the electrons. Example: 3s orbital will be filled first and then 3p orbital. Orbital.

Sidgwick made the observation, since known as the EAN rule, that in a number of metal complexes the metal atom tends to surround itself with sufficient ligands that the resulting effective atomic number is numerically equal to the atomic number of the noble-gas element found in the same period in which the metal is …

(a) Bohr Bury Rules: (i) The maximum number of electrons present in a shell is given by the formula 2n2 (where n is shell no.) (ii) The maximum number of electrons that can be accommodated in the outer most orbit is 8. (iii) Electron are not accommodated in a given shell, unless the inner shells are filled.

a theory of atomic structure in which the hydrogen atom (Bohr atom ) is assumed to consist of a proton as nucleus, with a single electron moving in distinct circular orbits around it, each orbit corresponding to a specific quantized energy state: the theory was extended to other atoms.

Bury, in full John Bagnell Bury, (born Oct. 16, 1861, County Monaghan, Ire. —died June 1, 1927, Rome, Italy), British classical scholar and historian.

Niels Henrik David Bohr

Five years later, the model would be disproved by Hans Geiger and Ernest Marsden, who conducted a series of experiments using alpha particles and gold foil – aka. the “gold foil experiment.”

Niels Bohr was born on October 7, 1885, in Copenhagen, Denmark, to mother Ellen Adler, who was part of a successful Jewish banking clan, and father Christian Bohr, a celebrated physiology academic.