These crystals of the mineral pyrite are a good example of a solid.
Click on image for full size
Courtesy of Corel
Solid is one of the four common states
of matter. The three others are gas,
liquid, and plasma.
There are also some other exotic states of matter that have been discovered
in recent years.
Unlike liquids and gases, solids have definite shapes. If you pour some milk
into a glass or fill a balloon with helium, the liquid (milk) or gas (helium)
takes on the shape of the container (the glass or balloon). A solid keeps its
or molecules in a solid are packed
together much more tightly in a solid than in a gas or a liquid. The atoms or
molecules in a solid have fixed positions; they don't move around like atoms
or molecules in a gas or liquid do. That's why liquids and gases can flow,
but solids don't.
Solids are usually much more dense
than liquids and gases, but not always. Mercury,
a metallic element that is
a liquid at room temperature, is denser than many solids. Aerogel,
a very unusual human-made solid, is about 500 times less dense than water.
Many solid materials will melt when heated. When solids melt,
they become liquids. For example, when iron is heated to a temperature
around 1,538° C. (2,800° F.) it melts and becomes molten iron. When
liquids are cooled they can freeze
and become solids. A familiar example is liquid water
turning into ice. Under certain conditions (usually low pressure)
some solids can turn directly into a gas without first melting and becoming
a liquid. When a solid turns directly into a gas we call the change "sublimation".
Maybe you have seen dry ice (which is very cold, frozen carbon
Crystals, wood, rocks,
most metals, and glass are all examples
of common solids. Your bones and teeth are also solid materials. That's a good
thing... it would be hard for you to eat or get around if it weren't for solids!
Shop Windows to the Universe Science Store!
Our online store
on science education, classroom activities in The Earth Scientist
specimens, and educational games
You might also be interested in:
Plasma is known as the fourth state of matter. The other three states are solid, liquid and gas.In most cases, matter on Earth has electrons that orbit around the atom's nucleus. The negatively charged...more
Most things around us are made of groups of atoms bonded together into packages called molecules. The atoms in a molecule are held together because they share or exchange electrons. Molecules are made...more
Density is a measure of how much mass is contained in a given unit volume (density = mass/volume). It is usually expressed in kg/m^3. Put simply, if mass is a measure of how much ‘stuff’ there is in an...more
Everything you see around you is made of tiny particles called atoms. There are many different types of atoms, each with a special combination of protons , neutrons and electrons . These different types...more
A snowman, glass of water and steam might look very different but they are made of the same stuff! Just like any substance, water can exist in three different forms, called states: solid, liquid and gas....more
Carbon dioxide (CO2) is a kind of gas. There isn't that much carbon dioxide in Earth's atmosphere, but it is still very important. Carbon dioxide is a greenhouse gas. That means it helps trap heat coming...more
The periodic table on the left separates elements into three groups: the metals (green in the table), nonmetals (orange), and metalloids (blue). Most elements are metals. They are usually shiny, very...more