Question

what is formula to find number of electron in subcshells

Answer 1

Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons.[1] Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may have two or even three incomplete outer shells. (See Madelung rule for more details.) For an explanation of why electrons exist in these shells see electron configuration.[2]

The electrons in the outermost occupied shell (or shells) determine the chemical properties of the atom; it is called the valence shell.

Each shell consists of one or more subshells, and each subshell consists of one or more atomic orbitals.

Answer 2

Electronic Configuration of Elements

According to the postulate of Neils Bohr, “electrons revolve around the centre of an atom (nucleus) in a predictable pathway named orbits”. The representation of the orbits is done by letters and numbers such as K, L, M, N, O…. and 1,2,3,4…. respectively. The arrangement and distribution of electrons in different orbits was given by Bohr and Bury.

The arrangement of electrons in different shells and sub-shells is known as the electronic configuration of a particular element. The electronic configuration diagram represents an element in its ground state or stable state. There are a set of rules to remember while distribution off electrons in different orbits.

• Rule 1: The maximum number of electrons present in a particular shell is calculated by the formula 2n², where “n” represents the shell number. For instance, K shell is the first shell and it can hold up to 2(1)²=2 electrons. Similarly, L shell is the second shell and it can hold up to 2(2)²=8 electrons. This formula helps to calculate the maximum number of electrons that an orbit can accommodate.

• Rule 2: The maximum capacity to hold electrons in the outermost shell is 8.

• Rule 3: The electrons will fill the inner shells before the outer shells. First electrons will fill the K-shell and then L shell and so on. Thus, electronic configuration of elements follows an ascending order.