Three States Of Matter

The three states of matter are solid, liquid and gas.

Solid

Solids have strong atomic bonding and high viscosity, resulting in high density, highly incompressible and hence, an inflexible shape. The atoms/molecules in a solid are closely packed together and occupy minimum space, usually in a regular pattern.

Due to strong intermolecular attractive and repulsive forces, motion is limited to random vibrations of the partricles about their mean closely packed lattice positions.

Liquid

Liquids have a definite volume but no fixed shape. The particles of a liquid are arranged in small clusters and condensed like those of a solid. These particles vibrate randomly near their mean positions, but their low viscosity and cluster-form enables them to change shape.

• When a liquid is poured into a container, it takes the shape of the container.
• The strong attractive forces between the particles are responsible for limiting the liquid particles near the surface of the liquid from escaping.

Gas

Gas has no definite volume and shape. Gases consist of weakly-bonded particles with no structure or long-range periodicity and they move vigorously and randomly at high speeds.

• Gases expand to fill any available space
• The particles in gases are far apart and have negligible attractive or repulsive forces and therefore, are easily compressible.

The different state of matter has different properties. This difference could be explained based on how individual atoms or molecules are held together in a matter.

Interesting Fact:

• There are more states of matter than the three listed above. What are they?

Comparing the three states of matter – Solid, Liquid & Gas

	Solid	Liquid	Gas
Volume	Definite	Definite	Indefinite (Takes the shape and size of container)
Shape	Definite	Definite (Takes the shape of container)	Indefinite (Takes the shape of container)
Compressibility	Not Compressible	Not Compressible	Compressible
Arrangement of atoms/molecules	– Closely packed together   – Orderly arrangement – Held together by large forces	– Closely packed in clusters of atoms or molecules   – Atoms/molecules slightly further apart compared to particles – Held together by large forces	– Atoms or molecules are very far apart and occupy any given space   – Negligible forces of attraction between atoms/molecules
Density	High (Usually)	High	Low
Forces between atoms/molecules	Very Strong	Strong	Very Weak
Movement of atoms/molecules	Can only vibrate about fixed positions	Able to move pass each other and not confined to fixed positions	Move in random manner independent of each other and at high speed

Note: Not all solids have high density, i.e. “ice” is a solid consisting of water molecules arranged orderly in an open hollow structure. The density of ice is lower than water (which is a liquid), and hence, ice can float on water!