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Structure of Matter is taught in the note for Structure and Properties of Matter. Read it below and look for the section on this topic.

Structure and Properties of Matter

10 min read

Matter is made of particles

All matter is made of tiny particles (atoms and molecules) that are always moving. The way the particles are arranged and how they move decide whether the matter is a solid, a liquid or a gas.

Particles in a solid, a liquid and a gasThree boxes of particles. In a solid they are packed in a regular pattern and only vibrate. In a liquid they touch but slide past each other. In a gas they are far apart and move quickly in all directions.Solidfixed pattern, vibrateLiquidclose, slide past each otherGasfar apart, move fast
Three states of matter
SolidLiquidGas
Particlespacked tightly in fixed positionsclose but able to slidefar apart and free
Shapefixedtakes the shape of its containerfills its container
Volumefixedfixedchanges easily
Compressible?nohardlyyes

Properties that come from the particles

PropertyWhat it isExample
Elasticitya material returns to its shape after a force is removeda spring, a rubber band
Cohesionparticles of the same substance attract each otherwater drops stay together
Adhesionparticles of different substances attract each otherwater sticks to glass
Surface tensionthe surface of a liquid acts like a stretched skinan insect walks on water
Capillaritya liquid rises in a very narrow tubewater climbing in a plant stem or a wick
Osmosiswater moves through a partially permeable membrane from dilute to concentrated solutiona root absorbing water
Surface tensionA needle floating on water, with a close-up of molecules. A molecule at the surface is pulled sideways and downwards by its neighbours, which makes the surface behave like a stretched skin. A molecule inside is pulled equally in all directions.needle floatssurface: net pull inwardsinside: balancedskin-likesurface
Capillary riseThree glass tubes of different widths standing in water. Water rises highest in the narrowest tube and least in the widest tube.narrow: rises mostmediumwide: rises leasth
Try itCapillary rise

A narrow tube is placed in water. The height the water climbs is inversely proportional to the radius of the tube: half the radius gives twice the height. (This simple model keeps the other quantities fixed and uses water in clean glass.)

Check yourself Which state of matter has particles that are far apart and move freely?
Check yourself A needle floats on water because of…
Try the osmosis lab
See water move across a membrane and measure the change in mass.

Key terms

Particle
A tiny piece of matter such as an atom or molecule.
Cohesion
Attraction between particles of the same substance.
Adhesion
Attraction between particles of different substances.
Surface tension
The skin-like behaviour of a liquid surface.

Summary

  • Matter is made of moving particles; their arrangement decides the state.
  • Elasticity, cohesion, adhesion, surface tension and capillarity come from forces between particles.
  • Capillary rise is greater in narrower tubes.
Elasticity