What Is Isotones , Isodaiphers , Isoelectronic And Isosters

Isotones
Two nuclides are isotones if they have the same neutron number N, but different proton number Z. For example, boron-12 and carbon-13 nuclei both contain 7 neutrons, and so are isotones.

Isodiaphers
In nuclear physics and radioactivity,isodiaphers refers to nuclides which have different atomic numbers and mass numbers but the same neutron excess, which is the difference between numbers of neutrons and protons in the nucleus
Eg: 90Th234 and 92U238
in thorium proton number is 90 and neutron number is 144
144-90 = 54
in uranium proton number is 92 and neutron number is 146
146 - 92 = 54

Isoelecteonic
Two or more molecular entities are described as isoelectronic if they have the same number of valence electrons and the same structure, i.e. number and connectivity of atoms, but differ in some of the elements involved.
Eg:CO and N2 and NO+

Isosters
Isosteres are atoms, molecules, or ions of similar size containing the same number of atoms and valence electrons.
Eg:Consider neon, the noble gas at the end of the second row of the periodic table.

To the left of it, fluorine has one fewer electron. If fluorine ionizes, it gains an electron to become F-, which is an isostere of Ne.

Similarly, O2- is an isostere of Ne and F-.

In fact, neon is part of a group of six isosteres. These are:

O2-, F-, Ne, Na+, Mg2+, Al3+

Hope this will help you :)