Change Flashcards
Define physical chnage
A change that does not alter the chemical nature of the substance, and in which no new chemical substances are formed
What are examples of physical change?
Phase chnagez
What is Kinetic molecular theory also known as?
The particle model of matter
Define particle model of matter
Scientific model used to explain that all matter is made up of particles and to explain the properties and behaviour of matter
Define particles
atoms, molecules, ions
What does the model state?
- Made up of atoms
- Particles always moving
- Empty space between
- Forces of attraction
How big are the particles?
So small - can’t see under microscope
When do particles move faster?
Heaterd
When do particles move slower?
Lose heat
What exists between spaces?
Nothing
What does it mean when forces of attraction is strong?
Particles are close
What does it mean when forces are weak?
Particles are far away
How close are the particles for solids?
Very close together
What forces of attraction do solids have?
Strong forces of attraction - held tightly togeteht
Can solids be compressed?
Cannot be compressed
How do solids move?
Do not flow - vibrate
What type of kinetic energy do solids have?
Low kinetic energy
Shape and volume of solids?
Fixed shape and volume
Density of solids?
High density
How close are liquids particles?
Close together
Forces of attraction of liquids?
String but weaker than solids
How do liquids move?
Slide over each other
Can liquids be compressed?
Cannot he compressed
Why can liquids move easily?
Kinetic energy between particles are greater than solids, weaker than gases
Volume of liquids?
Fixed volume
Shape of liquids?
No fixed shape
What are gases particles like?
Well spread out
Forces of attraction for gases?
No forces of attraction
Compress of gases?
Easy to compress
How do particles of gases move?
Very easily - high kinetic energy
Volume and shape of gases?
No fixed volume and no fixed shape
Density of gases?
Low density than liquids
What causes a material to change state?
Heating and cooling
Name six phase changes
- Melting
- Freezing
- Evaporation
- Condensation
- Sublimation
- Deposition
When does phase change take place?
Particular temperature
Define temperature
Average kinetic energy of particles
Define melting point
Substance is the so start temperature at which the substance changes from the solid to liquid phase
Define boiling point
Constant temperature at which the substance changes from liquid to gaseous phase
What is heat?
Form of energy
When matter is heated, what happens to particles?
Temperature increases - particles live faster - kinetic energy increase
What happens during phase change?
- Temperature remains constant
- Change
- Energy absorbed/released
What is there in the change?
Arrangement
Movement
Attractive forces
Spaces between
Define chemical change
Change in which the clerical nature of the substances involved changes and nee chemical substances are formed
What does chemical change involve?
- Colour change
- Large change in temperature
- Formation of gas - bubbles
- Formation of precipitate - solid
What is the difference between the temperature of physical changes and chemical changes?
Chemical change is much much larger than physical change
What does a chemical change involve?
Talking of existing bonds and the formation of a new bonds
What must happen in order to break bonds?
Energy must be absorbed – endothermic process
What happens when you bonds are formed? 
Energy is released – exothermic process
Synthesis reaction
Combustion of hydrogen rocket propulsion
Define synthesis reaction
One in which two or more simple substances react to form a more complex product