Khamis, 13 November 2008

THE STRUCTURE OF THE ATOM

ATOM:The smallest particle of an element that can participate in a chemical
reaction.

MOLECULE:A group of two or more atoms which are chemically bonded together .

ION: A positively-charged or negatively-charged particle.

THE KINETIC THEORY OF MATTER

SOLID

  • Has fixed volume and shape
  • Cannot be compress
  • The particles are packed closely together in an orderly manner
  • There are strong forces between the particles.
  • The particles can only vibrate and rotate about their fixed positions

LIQUID

  • Has fixed volume
  • It does not have a fixed shape but takes the shape of the container
  • Cannot be compress easily
  • The particles are packed closely together but not in orderly arrangement
  • The particles are held together by strong forces but weaker than the forces in a solid
  • The particles can vibrate, rotate and move throughout the liquid.They collide against each other.

GAS

  • Does not have fixed shape or volume
  • Can be compressed easily
  • The particles are very far apart from each other and in random motion
  • Weak forces between particles
  • Can vibrate, rotate and move freely.The rate of collision is greater than liquid.

ISOTOPES AND THEIR IMPORTANCE

WHAT IS ISOTOPES?

: Isotopes are atoms of the same element with different number of neutrons

USES OF ISOTOPES

  • Cobalt-60 = Used in Radiotheraphy for the treatment of cancer
  • Gamma Rays of Cobalt-60 = Used to destroy bacteria in food without changing the quality of food.
  • Carbon-14 =used to estimate the age of fossils and artefacts
  • Phosphorus-32 = study the metabolism of phosporus in plants
  • Iodine-131 = used to diagnose thyroid glands diseases



Tiada ulasan: