This question has been at the centre of nuclear physics for many years. In the 30's when the subject began to be understood, it was postulated that there must be a force, that was not understood, but which overcomes the repulsion between similarly charged protons which you would normally expect, and also binds the uncharged neutrons into the nucleus. This came to be known as the Strong Nuclear Force. Work to try to establish what this force was and how it worked has been ongoing ever since. It is very short range and only effective inside the nucleus. It was gradually realised that what were thought to be fundamental particles, the proton and neutron, are not that at all, and there are many other particles involved, quarks, gluons, hadrons, among them. The subject is very complex, and scientists are still trying to explain it all, with the help of more energetic machines. The new one at CERN should give more data when it starts up. If you want to read more I can recommend in Wikipedia entries under Standard Model, Strong Interaction, and Nuclear Force, but warn it is hard stuff!
subatonic particles
It varies from same as in a solid (glass, mercury), to that of a gas (and check out the "triple point") You should study - surface tension.
If we are just considering the "basic" nuclear reaction in a "regular" nuclear reactor, the particles of interest are the uranium-235 atoms (which are fissionable), and the neutrons, which get loose and cause fissions when they are absorbed by the U-235 atoms. We could broaden this to include some other reactions, but this is a fabulous place to begin to investigate nuclear physics.
Atoms are in a solid but as in particles it depends on the object.
when you push the plunger are the air particles closer together in the syringe or in the bubble
Nuclear particles are held together by the strong nuclear force, which is one of the four fundamental forces of nature. This force is responsible for binding protons and neutrons together in the atomic nucleus.
Particles are held together by several forces, including the electromagnetic force, weak nuclear force, and strong nuclear force. The electromagnetic force is responsible for holding atoms together through interactions between charged particles. The weak nuclear force is involved in nuclear decay processes, such as beta decay. The strong nuclear force is responsible for binding protons and neutrons together in atomic nuclei.
Particles are held together by four fundamental forces: gravitational force, electromagnetic force, weak nuclear force, and strong nuclear force. Gravitational force attracts particles with mass towards each other, electromagnetic force acts between charged particles, weak nuclear force is responsible for radioactive decay, and strong nuclear force binds protons and neutrons together in atomic nuclei.
they are not held together.
The proton is one of the fundamental particles of the nucleus, the other is the neutron. The proton is positively charged, the neutron has no charge. They are held together by the strong nuclear force.
Protons and neutrons are made up of smaller particles called quarks, which are held together by strong nuclear force. Electrons are elementary particles and do not have smaller constituents.
Particles, such as atoms and molecules, come together to form an object through various forces like electromagnetic interactions and nuclear forces. These particles are held together by strong bonds that determine the physical and chemical properties of the object. The arrangement and type of particles present in an object determine its structure and behavior.
Protons and neutrons combine in groups of three to form atomic nuclei. Protons have a positive charge and neutrons have no charge; together, they are held together by the strong nuclear force to form stable atomic nuclei.
The largest force acting with in an atom is the van der wells force. It is several orders of magnitude stronger the the weak nuclear forces. It really depends on what sub atomic particles you are talking about.
Hideki Yukawa proposed the first theory of the strong force via meson exchange particles.
bonds
The strong nuclear force.