Why is the mass of nucleus always less than the sum of the masses of its constituents, neutrons and protons?

Question

Please answer this question according to 12th CBSE level

Answer 1

I m not sure to be with the 12th CBSE level but according to me the mass of the nucleas is always equal to it's constituents, Neutros and Protons as neutrons and protons make up the nucleas of an atom

Answer 2

I'm not sure what 12th CBSE level is - but I think it's equivalent to an A-Level in the UK.

The mass of a nucleus does not weigh as much as the constituent parts because of something called the 'mass defect'.
It takes energy to bind together nuclei and therefore the energy required to do this is given by Einstein's famous E = mc^2 formula.

Relative to the size of a single atom, the energy it takes to bind it enormous.

The tiny amount of mass missing is converted to energy so the nucleons bind together correctly - sometimes this is called binding energy.

Normally within physics we class 1 nucleon as 1/12 of the mass of a Carbon-12 nucleus, this is called an amu (atomic mass unit).

The real reasons for mass defect are much more complex and can be examined both in Quantum mechanical and Reletivistic ways, but I don't think you will be going this deep into it yet.

You also get a release of energy by splitting atoms apart (fission rather than fusion) - which is what happens in a nuclear reactor.

Answer 3

The following may be a thought to pursue. It begins with the electron. This small bit of matter comes into existence by bonding to its own frequency, which is the reason it is able to remain as a three-dimensional object and not revert directly back to becoming electromagnetic energy.

Electrons are formed of electromagnetic energy. This is evidenced when a high frequency photon enters near the center of an atom and is divided into a negative and positive electron pair. Both of these masses are, obviously, able to revert back into becoming electromagnetic energy.

The reason it requires the presence of a mass to convert electromagnetic energy into becoming an electron is that this frequency must make a arc of more than 360 degrees, then overlap part of its frequency to remain bonded. This cannot be done apart from the presence of a mass. The bonding energy you seek is the overlap of the electromagnetic energy.

http://360.yahoo.com/noddarc
http:/timebones.blogspot.com "The Problem and Repair of Relativity" is a short paper that may be of help.

Answer 4

the mass of nucleus is the sum of masses of its constituents -the protons and neutrons

Answer 5

well thats bcoz binding energy. its the energy that binds neutrons n protons 2gther. so some of the mass is converted into binding energy