chap 2 particulate nature of matter

• the FOA in liquids are strong
• the FOA in gas are weak
• what is the arrangement of particles in solids ?

  very closely packed, orderly arranged
• what is the arrangement of particles in liquids ?

  closely packed, randomly arranged
• what is the arrangement of particles in gass ?

  far apart, random order
• what is the movement of particles in solids ?

  vibrate and rotate about fixed positions
• what is the movement of particles in liquid ?

  slides over one another and change position within liquid
• what is the movement of particles in gas ?

  move about freely and randomly at high speeds
• the shape and volume of solids are definite
• the shape and volume of liquids are indefinite and definite respectively
• the shape and volume of gases are indefinite
• why are the shape and volume of solids definite ?

  particles are held together by very strong forces of attraction.

  particles are orderly arranged and cannot move freely but can only vibrate about their fixed positions
• why are the shape and volume of liquids are indefinite and definite respectively ?

  particles are held together by strong forces of attraction which are not strong enough to hold them in fixed position

  particles are disorderly arranged, able to move and slide past one another, exchanging positions but only within the liquid and not freely anywhere
• the shape and volume of gases are indefinite ?

  particles are held together by weak forces of attraction hence can move freely and randomly in all directions to occupy any available shape and volume of container
• why can't solids be compressed ?

  particles are very closely packed with very little intermolecular space between particles, hence, particles cannot come closer to occupy a smaller volume when a force is applied
• why can't liquids be compressed ?

  particles are closely packed, little intermolecular space between particles, hence, particles cannot come closely to occupy a smaller volume when a force is applied
• why can gasses be compressed ?

  particles are very far apart, there are large intermolecular spaces between particles, allowing particles to come closer and take up a smaller volume when a force is applied
• why are solids very dense ?

  particles are very closely packed, hence, large number of particles per unit volume
• why are liquids dense ?

  particles are closely packed hence large number of particles per unit volume
• why are gasses not dense ?

  particles are very far apart hence lesser number of particles per unit volume
• impurities in a solution causes melting and boiling to take place over a range of temperatures
• impurities in a solution decreases the melting points of the pure substance
• impurities in a solution increases the boiling point of a pure substance
• boiling occurs throughout the liquid while evaporation occurs only at the surface of the liquid
• boiling take place only at boiling point while evaporation takes place at temperatures below boiling point
• at boiling point, all particles absorb energy to overcome the forces of attraction but at evaporation, only particles at the surface break free from liquid to escape as a gas
• solids gain heat

  when temperature increases, particles gain kinetic energy and vibrate more rapidly about fixed positions
• solid to liquid

  temperature remains constant as heat absorbed by particles is used to overcome the forces of attraction holding the particles together
• liquids gain heat

  temperature increases, particles gain more kinetic energy and slide past each other more rapidly and move further apart
• liquid to gas

  temperature remains constant as heat absorbed by particles is used to overcome the intermolecular forces of attraction holding the particles together
• gas gain heat

  temperature increases, particles gain more kinetic energy and move more rapidly and further apart
• gas loses heat

  temperature decreases, particles lose kinetic energy and have less KE, causing them to move slower and closer together
• liquid loses heat

  temperature decreases, particles lose kinetic energy and have less KE, causing them to slide past each other more slowly and move closer together
• solid loses heat

  temperature decreases, particles lose kinetic energy and have less KE, causing them to vibrate and rotate slower about their fixed position
• gas to liquid

  temperature remains constant as heat is released to surroundings when particles slow down and move closer to one another with formation of stronger FOA
• liquid to solid

  temperature remains constant as heat is released to surroundings when particles slow down with formation of stronger FOA
• rate of diffusions can be affected by temperature and relative molecular mass
• increase in temperature increases the kinetic energy of particles, hence particles move faster
• the greater the relative molecular mass of a substance, the slower its rate of diffusion
• relative mass of proton is 1