States of matter.pdf

States of matter Based on the GCSE Cambridge curriculum How many states of matter? Activity! 9 volunteers divided into 3 groups of 3 One group will mimic the movement of solid particles, one will do liquid, and the last will do gas! What did we learn? Properties Property...

States of matter Based on the GCSE Cambridge curriculum How many states of matter? Activity! 9 volunteers divided into 3 groups of 3 One group will mimic the movement of solid particles, one will do liquid, and the last will do gas! What did we learn? Properties Property Solid Liquid Gas Fixed shape yes No, take the shape No, take the shape of the bottom of of the whole the container container Fixed volume yes yes No, take the volume of the container Density high Less than solids, Low but still higher than gases Can be compressed No Yes Yes (much more compressible than liquids Can be poured or No Yes Yes flow Particle theory State changes Melting When a solid changes to a liquid Requires heat energy which transforms into kinetic energy allowing te particles to move Occurs at a specific temperature known as the melting point (m.p.) Boiling Boiling is when a liquid changes into a gas Requires heat which causes bubbles of gas to form below the surface of a liquid, allowing for liquid particles to escape from the surface and within the liquid Occurs at a specific temperature known as the boiling point (b.p.) Evaporation Evaporation occurs when a liquid changes into a gas and occurs over a range of temperatures Evaporation occurs only at the surface of liquids where high energy particles can escape from the liquid's surface at low temperatures, below the b.p. of the liquid The larger the surface area and the warmer the liquid surface, the more quickly a liquid can evaporate Freezing Freezing is when a liquid changes into a solid This is the reverse of melting and occurs at exactly the same temperature as melting, hence the melting point and freezing point of a pure substance are the same. Water, for example, freezes and melts at 0 ºC Requires a significant decrease in temperature (or loss of thermal energy) and occurs at a specific temperature Condensation Condensation occurs when a gas changes into a liquid on cooling and it takes place over a range of temperatures When a gas is cooled its particles lose energy and when they bump into each other they lack the energy to bounce away again, instead they group together to form a liquid The kinetic theory When substances are heated, the particles absorb thermal energy which is converted into kinetic energy. This is the basis of the kinetic theory of matter Heating a solid Heating a solid causes its particles to vibrate more and as the temperature increases, they vibrate so much that the solid expands until the structure breaks and the solid melts On further heating, the now liquid substance expands more and some particles at the surface gain sufficient energy to overcome the intermolecular forces and evaporate When the b.p.temperature is reached, all the particles gain enough energy to escape and the liquids boils Heating curve Cooling curve How does a hot air balloon work? As the air inside a hot air balloon is heated up, it expands and the balloon gets bigger The density of the balloon decreases and it rises Temperature and pressure of a gas For a constant amount of gas at a constant volume, the higher the temperature of the gas, the higher the pressure That is because as you heat the gas particles, the gas particles gain gain kinetic energy They will hit the walls of the container more frequently They will hit the walls of the container more strongly This results in a higher pressure of the gas