THERMAL EXPANSION

less

The solid form of most substances is denser than the liquid phase; thus, a block of most solids will sink in the liquid. However, a block of ice floats in liquid water because ice is _________ dense.

9%

Upon freezing, the density of water decreases by about ____

4ºC (40ºF).

Water expands with increasing temperature (its density decreases) when it is at temperatures greater than _________________ .

+4ºC

Water is densest at _________

moving more

When a substance is heated, its constituent particles begin ________________ ________, thus maintaining a greater average separation with their neighboring particles.

volumetric thermal expansion coefficient

is the most basic thermal expansion coefficient. illustrates that, in general, substances expand or contract when their temperature changes, with expansion or contraction occurring in all directions

Thermal expansion

is the tendency of matter to change in volume in response to a change in temperature.

potential

A curve describing the situation where the difference in the potential energies of an object in two different positions depends only on those positions.

negative thermal expansion

A number of materials contract on heating within certain temperature ranges; this is usually called _____________________, rather than "thermal contraction.

hydrogen bond

A weak bond in which a hydrogen atom in one molecule is attracted to an electronegative atom (usually nitrogen or oxygen) in the same or different molecule.

thermal motion

Atoms and molecules in a solid, for instance, constantly oscillate around its equilibrium point. This kind of excitation is called ___________________

solid

For a _________, we can ignore the effects of pressure on the material, and the volumetric thermal expansion coefficient can be written as ... .

one third

For isotropic material, and for small expansions, the linear thermal expansion coefficient is _____ ______the volumetric coefficient

one half

For isotropic materials, and for small expansions, the linear thermal expansion coefficient is ___________ of the area coefficient.

isotropic

Having properties that are identical in all directions; exhibiting isotropy.

decreasing temperature

However, it expands with __________________ when it is between +4ºC and 0ºC (40ºF to 32ºF).

gas

In the case of a _____, expansion depends on how the pressure changed in the process because the volume of a gas will vary appreciably with pressure as well as temperature.

asymmetric

Inter-particle potential usually takes an ______________________ form, rather than a symmetric form as a function of particle-particle distance. This is why matters expands and contracts as temperature changes

linear expansion coefficient.

It is the fractional change in length per degree of temperature change

rare

Materials which contract or maintain their shape with increasing temperature are __________

increase

Objects expand in all dimensions. That is, their areas and volumes, as well as their lengths, ____________________ with temperature.

isotropic

Substances that expand at the same rate in every direction are called

linear expansion coefficient

The change in length measurements of an object due to thermal expansion is related to temperature change by a _____________________________, which is given as .

coefficient of thermal expansion

The degree of expansion divided by the change in temperature is called the material's __________________________________ it generally varies with temperature.

linear thermal expansion coefficient

The fractional change in length per degree of temperature change.

area thermal expansion coefficient

relates the change in a material's area dimensions to a change in temperature.