Why does matter expand when heat has been absorbed?

Answer 1

Heat energy causes all matter to expand, a reason for this strange occurrence is that when a particular substance receives heat whether it be through conduction, convection or radiation the atoms inside the substance become more energised therefor needing more space to move, they push the outside boundaries making the substance expand. If the substance receives an exceeding amount of heat energy it will change states of matter.

I hope this valubale information comes of use.

Answer 2

Heat and Expansion

Yes.

According to the spring ball model of solids, on exposing solids to thermal stress, the potential energy will increase as a whole in the system of molecules or ions or atoms ( as the case may be) that make-up the object mentioned above. This means the distance between any two particles increases, and hence the solid expands if free from any other stress.

One exception to this rule is water between 0oC and about 4oC. This is why ice floats on water, effectively because unlike other substances, the water in its solid state (ice) is less dense than water in its liquid state! This means that 1m cubed of ice will weigh less than 1m cubed of water, so, the ice, according to Archimedes principal, when submerged in water, it will float, because it displaces an amount of water for which the mass of the submerged ice that caused that displacement is less than the mass of the displaced water. The same applies to hot air balloons in air.

In addition to water, the elements bismuth and antimony also expand when they solidify. Other materials have negative expansion coefficients over some temperature ranges--e.g. shrink fit/shrink wrap polymers.

Answer 3

When you heat a substance (whether liquid, solid, or gas) the molecules vibrate more and more, which make them move farther apart, and then there is more empty space in between.
A helium balloon is a good example of this.
On a cold winter day, you decide to buy a helium balloon (for whatever reason) after you pay for it, and it is all nice and filled with helium for you, you take it outside on the way to your car. On your way you notice that the balloon looks all saggy and it looks as if most of the air was taken out of it. But then, when you take it into your car, which is all heated at that time, it takes back it's original form. This all happens, because the cold air made the molecules in the balloon move closer together, and the warm air made them all spread farther apart.
I hope that this helped any eight graders with their chemistry homework.
*ptysiu* :P
Recall that all materials are made up of atoms. At any temperature above absolute zero (-273 degrees celsius) the atoms will be moving. In a solid they will be vibrating in fixed positions, in a liquid thy will be jostling past each other and in a gas they will be whizzing past each other at very high speeds. When a material is heated, the kinetic energy of that material increases and it's atoms and molecules move about more. This means that each atom will take up more space due to it's movement so the material will expand. When it is cold the kinetic energy decreases, so the atoms take up less space and the material contracts.

Answer 4

Thermal energy (heat, or more correctly temperature) is the net effect of the molecules of a given substance moving about faster - the faster they move, the more forcefully they bump into each other, which causes the substance to generally expand.

Answer 5

When heat is absorbed by matter, the kinetic energy of its particles increases, causing them to move faster and spread apart. This increased movement creates more space between the particles, leading to expansion of the matter.

Answer 6

when the molecules get heated up, they move around more, making the matter expand

Answer 7

I think when the heat is passed to a substance the molecules start vibrating increasing the molecular distances,thus the heat starts transfering from one molecule to other.