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Isotones

Atoms are the smallest unit of matter forming a chemical element. Each atom is composed of a nucleus and several electrons bound to the nucleus. A number of neutrons and protons are present in the nucleus. Atoms that have the same number of neutrons but a different number of protons are Isotones.

History

James Chadwick was the 1st, who boldly stated that there was a new type of fundamental particle that is neutral and called them Neutrons.

He derived the mass of Neutron with considerable accuracy and found that the mass of a neutron was very close to that of a proton.

German physicist K. Guggenheimer formed the term ‘isotone’ by changing the ‘p’ in isotope (p refers to proton) to ‘n’(Neutron).

Isotones Explained

Basically these are atoms that have the same number of neutrons but a different number of protons as mentioned.

This can be shown as,

\(^a_{p}X, \, ^b_{q}Y, \, ^c_{r}Z\), these three atoms(\(X, Y, Z\)) have masses(\(a, b, c\)) respectively, and no. of protons(\(p, q, r\)) respectively.

\(
\begin{align}
\text{No. of Neutrons} \, = \, & a – p \\
& b-q \\
& c – r \\
\end{align}
\)

Now, if \((a – p) = (b – q) = (c – r) = \text{(say)} N\),

Hence, \(X, Y, Z\) are isotones.

Related Topic: Isodiaphers

Isotones Examples

\(^{36}_{16}\bf{S}, \, ^{37}_{17}\bf{Cl}, \, ^{38}_{18}\bf{Ar}, \, ^{39}_{19}\bf{K}, \, \& \, ^{40}_{20}\bf{Ca}\), isotone of 20. 
These all are isotones since they contain 20 neutrons each.

\(^2H, \, ^3{He}\), isotone of 1.

\(^9{Be}, \, ^{10}B\), isotone of 5.

\(^{13}C, \, ^{14}N\), isotone of 7.

\(^{97}{Ro}, \, ^{99}{Ru}\), isotone of 55.

\(^{86}{Kr}, \, ^{88}{Ra}, \, ^{89}Y, \, ^{90}{Zr}, \, ^{92}{Mo}\), isotone of 50.

And the list of examples goes on.

FAQs

What are isotones?

Atoms that have the same number of neutrons but a different number of protons are isotones.

What is an example of isotones?

\(^{39}_{19}\bf{K} \, \& \, ^{40}_{20}\bf{Ca}\), are a few examples.

Are isotones and isotopes similar?

Isotopes have the same number of protons, and a different number of neutrons, while isotones have the same number of neutrons and different numbers of protons.

Who discovered neutrons?

James Chadwick discovered neutrons.

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