Topic 1: Particles Flashcards
What are the three states of matter?
solid, liquid, gas
Describe the arrangement and movement of particles in solids
The particles are packed closely together in a regular arrangement. The particles vibrate in fixed positions.
Describe the arrangement and movement of particles in liquids
The particles are close together but able to move past each other. The particles vibrate and move around each other.
Describe the arrangement and movement of particles in gases
The particles are well separated with no regular arrangement.
The particles vibrate and move freely at high speeds.
How do the relative energies of particles in a solid, liquid and gas compare>
Particles in a solid have the least amount of energy. Particles in a gas have the most energy.
What are the names for the state changes from solid to liquid and vice versa?
Solid to liquid= melting
liquid to solid= freezing
What are the names for the state changes from liquid to gas and vice versa?
Liquid to gas= evaporation
gas to liquid= condensation
Describe the forces between particles in solids, liquids and gases
Solids: Strong forces of attraction between particles which keep them in fixed positions.
Liquids: Weaker attractive forces than in solids.
Gases: Weakest intermolecular forces so particles move randomly
How does a physical change differ from a chemical change?
A physical change involves changes in the forces between particles. The particles themselves remain the same and the chemical properties remain the same. A chemical change is different as it affects the chemical properties of the substance.
True or false?
‘Physical changes are relatively easy to reverse’
TRUE
Relatively easy to reverse since no new product is formed during the changes of state.
Describe what happens, in terms of particles, when a solid is heated and melts into a liquid.
When heated, particles absorb thermal energy and convert it into kinetic energy. The particles in the solid vibrate more, causing the solid to expand until the structure breaks and the solid turns into a liquid.
Describe what happens, in terms of particles, when a liquid is heated and evaporates into a gas
When heated, the particles in a liquid expand. Some particles on the surface gain sufficient energy to overcome the intermolecular forces and evaporate. At the boiling point, all of the liquid particles gain enough energy to evaporate.
Substance A melts at -200 degrees and boils at -183 degrees. What state is A at -174 degrees.
Liquid
Substance B melts at -5 and boils at 23, what state is B at -7
Solid
Why do solids, liquids and gases expand when heated?
When a substance is heated the molecules vibrate faster. This causes the space between the atoms to increase.
What is an advantage of the current particle model?
It provides a simple understandable model to explain the three states of matter.
Particles in the particle model are represented by ________ _________
Inelastic spheres
What are the limitations of the particle model?
Doesn’t take into account forces of attraction between particles. Doesn’t take into account the size of particles and space between them.