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Name: Vidura
Status: student
Grade: 9-12
Location: Outside U.S.
Country: Sri Lanka
Date: Summer 2011


Question:
Most matters have the 3 states of solid, liquid and gas. Likewise, do sub atomic particles like electrons, protons have boiling points and melting points?

Replies:
Hi Vidura,

Let me try to explain this in the simplest way:

The essence of matter is composed of subatomic particles. To change the 'state' of subatomic particles to a solid or liquid or gas by way of a freezing, melting or vaporizing point is a misconception as the basic constituents of all matter is made up of electrons, protons and neutrons.

Perhaps another question is how much energy is required to change the state of an atom. But that form of energy required isn't defined by a melting or freezing or vaporizing point, and its resulting form isn't a solid or liquid or gas. Rather its resulting form is a change in its energy state.

-Alex Viray


Vidura,

The three states of matter are due to attractions between substances holding the materials together. With molecules we would say the intermolecular forces are holding the molecules together to form the states of matter. As the material is heated the energy in the system increases until the energy is enough to break apart these intermolecular forces causing the phase transitions. When we take this idea and move it to subatomic particles this idea does not hold true in the fact that there is no interactions of this type that would hold a group of electrons or protons together. Therefore they would not have phase transitions as one sees in the states of matter.

Brad Sieve


Hello Vidura -

Your short answer is no. Identical particles usually cannot collect into substances.

It is true that most _substances_ have 3 states. A "substance" is a condensed condition of many identical smallest-pieces of matter. Usually the smallest-pieces are molecules. Electrons, on the other hand, are also smallest-pieces of matter, but they cannot gather together to make a condensed state because of their mutual electrostatic repulsion. They are all electrically negative, and collecting them together is energy-prohibitive on all size-scales. But when this net negative charge is cancelled out by some positive-charged population, such as a matching number of protons, then some of the weaker forces which attract can dominate the situation and help make a condensed substance. For electrons and protons in particular, that substance will be hydrogen, whose melting and boiling points are well known.

Neutrons are neutral particles... They are atomic particles which have no electrostatic charge to prevent them from condensing into a substance. It seems that the only stably condensed condition of neutrons we know of is the neutron star, in which the weaker attracting force is gravity. A very large number of neutrons is necessary to generate sufficient force to constrain the particles, so it is a bit different than our familiar substances in which most of the attracting force is between nearest neighbors. The stuff of a neutron star has been called "neutronium" and might be considered a substance. But of course it has been physically inaccessible to us and we don't really know its melting or boiling behavior from experience. Theoretically it is thought that pure neutronium is a super-fluid, and so it may be never a solid no matter the temperature. It is not even clear what temperature means in neutronium, because neighboring particles may not bounce off each other, and may not have identifiable individual velocities. I suppose some dissolved impurity such as protons and electrons (in equal numbers) might tend to set up crystal domains and act like a solid. But that impure neutronium might not be a defined substance. It might be merely a transition condition between pure neutronium and vacuum, existing in the lower pressures near the surface of the star. So a neutron star might have a solid crust having some tendency to liquify when hot. And astronomers have detected abrupt small changes in rates of pulses from pulsars, which some have interpreted as star-quakes in the neutron -star's solid crust. But perhaps there could be other causes for an abrupt change in rotation rate, such as themo-nuclear blow-off of non-neutronium accumulations on the surface. Unfortunately I'm not current on that topic.

I guess that is the closest thing to a "yes" answer I can think of. Anything made of atomic particles will be very different than normal substances, so its rules may be rather different than normal.

Describing a neutron star would not be complete without mentioning this: A physicist's daydream about the neutron-star surface condition is the sci-fi book "Dragon's Egg" by the late Robert L. Forward. I found it fun...

Jim Swenson


Vidura,

The terms solid, liquid, and gas refer to how tightly molecules are attached to each other. When the material heats up, the molecules vibrate faster. When the vibrations are not violent enough to break any bonds, the material is solid. When the vibrations are violent enough to make the molecules fly apart, the material is gas. When in between, when the molecules can move around but cannot fly apart, the material is liquid.

Subatomic particles do not link together in the same way as molecules. They are either joined together completely within an atom or flying freely. Electrons can be knocked free from atoms, but it is not due to temperature. If a particle hits an atom with enough energy, it might break one of the electrons away. If that atom and electron get close together, they will probably rejoin and emit a photon (a particle of light). Changing the state of subatomic particles is based on individual collisions rather than temperature.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College


Matter has the three phases you identified. Solids and liquids form due to attractive forces between those phases. Attractive forces also exist between the gas phase and the other two states of matter. Be aware that there are other states of matter. Solids have multiple crystal structures, a few liquids -- for example He at low temperatures (less than about 2 kelvins) becomes another phase -- its superfluid phase -- this is a quantum mechanical property. Now protons and electrons repel one another strongly, so they cannot form a macroscopic phase of protons or electrons. If you consider protons and electrons, they bond strongly forming hydrogen and it has three phases, but I do not think that is where your question is directed.

Vince Calder


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