ARRANGEMENT OF PARTICLES IN THE STATES OF MATTER

Solid
Ø The particles of solids are closely packed together in an organised way.
Ø The closely knit structure is due strong attractive forces (cohesive forces)
between the particles.
Ø In their fixed positions, they vibrate to and from so that increasing the
temperature of the solid increases this vibratory motion.
Ø At a certain temperature the solid breaks away from this knit structure
and the solid is said to have melted.
LIQUIDS
Ø The particles are further apart. They are not fixed as in solids but move
about in Brownian motion.
Ø Liquids can break a solute put in it. Its easier to dissolve a solute in hot
water because the particles have increased energy.
Ø The cohesive forces between the particles in liquids are weaker compared
to those in solids. Due to this liquids can flow and take up the shape of
the container in which they are put.
Ø When a liquid is heated molecules gain kinetic energy, they vibrate about
and expand. The space between them widens further apart and the liquid
changes into gaseous state by a process called vaporization.
GASES

· The particles are further apart and have increased random motion
compared to those in the liquid state.
· The cohesive force between the particles is extremely small and as the
particles move they collide with each other and with the walls of the
container in which they are trapped. This produces gas pressure.
· Gases are easier to compress indicates that there exists a large
intermolecular distance in gas than in liquids. Gas molecules or particles
can lose some of their energy and fall back into the liquid state by a
process known as condensation.
NOTE: Solids which when heated change directly into gas undergo the process
called sublimation.