Isoneutrons

Atom has the following three constituents

Mass of Proton almost = Mass of Neutron = 1830 X Mass of Electron.

• In an atom, Central Nucleus is surrounded by electrons at various energy levels. 
• The most successful model is Wave Mechanical Model, but that is a mathematical rather than a visual model.
• For our purpose, Bohr Atomic Model is enough. 

Bohr Atomic Model

• Atom consists of 
  • Central Nucleus: Containing all Protons & Neutrons with almost the whole mass concentrated here. 
  • Electrons: Revolves around the nucleus in a circular pattern (like planets around the sun) 
• Electrons can revolve only in certain specified orbits, with the electron in the innermost orbit having the smallest energy and the electron in the outermost orbit having the largest energy. 
• When an atom is provided energy either by strong heating or by bombardment with some fast-moving particle, Electrons in a natural state can jump to higher energy levels. But the atom doesn’t remain in that state for more than 10^-8 s & comes back to a normal lower energy level, emitting surplus energy in the form of Photons.
• Emitted energy can be Visible, UV or X-Ray, depending on the energy difference. 

• The property under which a heavy nucleus of an element disintegrates itself into smaller nuclei along with alpha, beta & gamma rays without being forced by any external agent to do so is termed radioactivity. 
• The phenomenon of radioactivity is natural and can’t be stopped. 
• It is found that all atoms with more than 83 protons; and a neutron-to-proton ratio of more than 1 as they are unstable. To achieve stability, unstable nuclei disintegrate spontaneously with the Alpha, Beta & Gamma Rays emission. 
• Henry Becquerel discovered the phenomenon of radioactivity.

Reason of Radioactivity

• Inside the nucleus, positively charged Protons & Neutral are present. Hence, if only Electrostatic Force is there, all nuclei must have split apart due to repulsive forces. But this is not the case & the nucleus is stable.
• But another force called Nuclear Force is working here. IT IS ATTRACTIVE FORCE EXISTING BETWEEN PROTON & PROTON and PROTON & NEUTRON. BUT THIS FORCE ACTS AT A VERY SMALL DISTANCE. Generally, Nuclear Forces overpower Electrostatic Forces inside the nucleus.
• But in the case of larger nuclei, nuclear forces cannot overpower electrostatic forces, and they exhibit radioactivity.

It measures the time it takes for a given amount of the radioactive substance to become reduced to half due to decay and, therefore, the emission of radiation.

Carbon Dating

• The technique of estimating the age of the remains of a once-living organism, such as a plant or animal
• It involves measuring the radioactivity of its C-14 Content (the half-life of C-14 is 5570 years).
• The ratio of C-14 / C-12 in nature is 1/106. 

Uranium Dating

• Uranium Dating is used for dating older but non-living things like rocks. 
• The age of rocks from the moon has been estimated to be 4.6 X 10^9 years, nearly the time of Earth’s origin.

• Atomic Number (Z) = Number of Protons
• Mass Number (A) = Number of Neutrons & Protons

Isotope

• Isotopes are nuclides with same Atomic Numbers but different Mass Numbers.
• E.g., U (92,235) & U (92,238 ) + C-12 & C-14
• Generally, isotopes don’t have different names except for isotopes of Hydrogen named Protium (H(1,1), Deuterium (H (1,2)) & Tritium (H(1,3)).

Isobars

• Isobars are nuclides having same Mass Number but different Atomic Numbers.
• E.g., K (19,40) & Ca (20,40) + C (6,14) & N (7,14) 
• They have different names. 

Isoneutrons

• Isoneutrons are nuclides having the same number of neutrons.
• Examples include 
  1. C (6,14) & O(8,16): Both have 8 neutrons
  2. H (1,3) & He (2,4): Both have 2 neutrons