Nodal points or Nodal planes

An ordital may also contain one or more points or planes where the probability of finding electron is zero. At such points or planes, electron density is found to be equal to zero. Such points are called nodal points and such planes are termed as nodal planes. The shapes of some orbitals are discussed below.   

Reducing Agent

A substance which accepts one or more electrons from the other is called an oxidizing agent. 

Oxidising agent

A substance which gives one or more electrons to the other is called a reducing agent. 

Redox reaction

Chemical reactions involving simultaneous oxidation and reduction are called redox reactions. 

Electronic configuraiton

Distribution of electrons in different orbitals of the atom of an element is called electronic configuration.

Quantum number

The number which designate and distinguish various atomic orbitals and electrons present in an atom are called quantum numbers.

Orbital

An orbital is an region in the three dimensional space around the nucleus where the probability of finding the electron is maximum. 

Orbit

An orbit is a definite circular path, whereas an orbital represents the total volume where the electron spends most of its time. 

Oxidation Number

Oxidation number of an atom represents the electric charge which the atom would have id the electrons shared in the compound are assigned to more electronegative atom or atoms. In simple ionic species, it is equal to the charge which the ion carries. 

Mass Number

It is equal to the sum of the number of protons and the number of neutrons in the nucleus. It is denoted by A. 

Atomic Number

It is equal to the number of protons in the nucleus or the number of positive charge on thee nucleus or the number of electrons in the neutral atom. It is usually denoted by Z. 

Hund's Rule

In a given set of orbitals of the same subshell, electron pairing is not possible until all the available orbitals are given one electron each. 

Aufbau Principle

During the filling of electrons in an atom, the orbital with a lower energy is filled up first before the filling of the orbital with a higher energy commences. 

Pauli's exclusion principle

No two electrons in a given atom can have the same four quantum numbers. 

Quantum Number

The  three quantum numbers are derived from Schrodinger's wave equation. these are principal, Azimuthal and Magnetic. The fourth quantum number is spin quantum which describes the spin of an electron in an atom. The main purpose off quantum numbers is to pin point and electron.

Shell

The energy level of Bohr's atom is termed as shell. The shells are represented by integers 1,2,3.. etc or by letters k,L,M,...etc.

Energy Level

Electron in an atom moves in certain specified energy level which is also known as orbit. Energy of an orbit is thus fixed. 

Neutron

It is a neutral particle of mass almost equal to the mass of proton. (1.008665 amu). 

Proton

Proton is a positively charged particle present in thee nucleus of an atom. It has mass of 1.00728 amu nad charge of 1.6022*10 power of -19 C.

Electron

Electron is a negatively charged particle which occupies the space outside the nucleus in an atom. It has mass of 0.00054859 amu and charge of 1.6022*10 power -19 C.