Chemistry Chapter 2

• Chemistry is after all the study of all matter, its composition, its properties, and its transformation from one form to another
• Matter


  All the substances and materials from which the physical universe is composed
• States of matter

  • Solid
  • Liquid
  • Gas
• Nowadays, there is a fourth state known as 'plasma' which is a hot ionized gas containing charge particles
• All substances are matter
• Matter


  Made up of tiny particles like atoms or molecules (groups of atoms) and elements or compounds
• Examples of matter

  • Air
  • Sea
  • Earth
  • Living creatures
  • Galaxies
• Mixtures

  Not pure substances, they contain useful substances mixed with unwanted material
• Obtaining useful substances from mixtures


  Chemists have to separate them from impurities
• Solid-liquid mixture


  Adding sugar to tea or coffee
• Solid-liquid mixture process


  Involves solute, solvent and solution
• The most common states of matter are solid, liquid and gas
• Water exists in all three states of matter - ice (solid), water (liquid) and steam (gas)
• Properties of each state of matter

  Depend on the forces of attraction between the particles which can be weak or strong
• Solid


  • Particles are packed very tightly together with strong forces between one another
  • They have little freedom of movement and can vibrate about a fixed position
  • They have a definite shape and volume
  • They have different colours and different properties
• Gases in a container

  1. Spread out to occupy the whole space of the container

  2. Take the shape and volume of the container
• Gases do not have a definite volume and shape of their own
• Properties of gases


  • Some have a smell
  • Some are odourless
  • Some have colours
  • Some are colourless
• All gases can easily be compressed and spread in all directions
• Brownian motion


  The continued random movement of small particles suspended in a gas or liquid, which arises from collisions with the gas or liquid particles
• Examples of Brownian motion


  • Motion of pollen grains on still water
  • Movement of invisible dust in a room
• Particles of matter are too small to be seen directly
• Diffusion


  Particles of one substance mix with and move through the particles of another substance
• Diffusion is mainly seen in liquids and gases
• Examples of diffusion


  • A drop of food colouring matter diffuses throughout the water in a glass
  • Particles of perfume move through the air and spread the room
• Mass of particles


  The bigger the mass, the slower the particles diffuse
• Mass of particles


  The smaller the mass, the faster the particles diffuse
• Temperature


  The higher the temperature, the faster the particles diffuse
• Differences between solid, liquid and gas

  • Solid: Definite volume and shape
  • Liquid: Definite volume but no definite shape
  • Gas: No definite volume and shape
• Diffusion of perfume particles

  1. Perfume particles move through the air and spread throughout the room

  2. Anyone in the room can eventually smell the perfume
• Factors affecting diffusion speed

  • Mass of particles
  • Temperature
• Mass of particles


  Inversely related to diffusion speed
• Temperature


  Directly related to diffusion speed
• Solid


  • Has definite volume and shape
  • Cannot be compressed, does not flow
• Liquid


  • Has definite volume but no definite shape
  • Cannot be compressed, flows in all directions
• Gas


  • Does not have definite volume and shape
  • Can be easily compressed, flows in all directions
• States of matter in the environment

  • Solid: Iron, Gold, Copper
  • Liquid: Water, Mercury, Vinegar
  • Gas: Argon
• Materials around us are subject to constant change
• Plants, animal materials, metals, and land areas undergo changes
• Unique identity of substances

  Each substance has a set of characteristics or properties that distinguish it from others