Unit 7: The Particulate Model of Matter Flashcards
• The particles possess ______energy which allows them to be in ______and ______motion.
• There are _____between the particles in matter to enable movement.
• The particles possess kinetic energy which allows them to be in constant and random motion.
• There are spaces between the particles in matter to enable movement.
Arrangement of particles are affected by:
Arrangement of particles are affected by:
• Distance between particles
• Density of Particles
• Ability of matter to be compressed
Particles of same size = ?
Particles of different size = ?
Particles of same size = element/compound
Particles of different size = mixture
Physical properties of solid:
Has Definite Volume
Has Definite Shape
Cannot be Compressed
Physical properties of liquid?
Has Definite Volume
Has No Definite Shape
Cannot be Compressed
Physical properties of gas?
Has No Definite Volume
Has No Definite Shape
Can be Compressed
Movement of particles in solids?
• The particles in solids are very closely packed in an orderly manner.
• The particles are arranged in a regular pattern.
• The particles vibrate and rotate about their fixed positions.
• There are the strongest forces of attraction between the particles.
• The particles have the lowest amount of kinetic energy among the three states of matter.
• The space between the particles is the smallest among the three states.
• The particles are held in their fixed positions due to strong attractive forces.
- Hence, using the particulate model of matter, it can be explained why solids have a definite shape and volume, and cannot be compressed.
Movement of particles in liquids?
Movement of Particles:
• The particles in liquids are closely packed (packed less closely than in solids) in a disorderly manner.
• The particles are not arranged in a regular pattern.
• The particles vibrate and move round one another (can flow).
• The particles slide past each other.
• There are strong forces of attraction between the particles.
• The particles have a lower amount of kinetic energy than in gases but higher than in solids.
• The space between the particles is smaller (but not much difference from solids).
• Particles are held together by strong attractive forces (have definite volume).
- Hence, using the particulate model of matter, it can be explained why liquids do not have a definite shape but have a definite volume, and cannot be compressed easily.
Movement of particles in gases?
• The particles in gases are far apart and are found in a disorderly manner.
• The particles move freely and randomly in all directions at high speeds (no definite shape).
• The particles do not have fixed positions and occupy and available space (flows easily).
• There are negligible/very weak forces of attraction between the particles.
• The particles move about rapidly in all directions.
• The particles have the highest amount of kinetic energy among the three states of matter.
• The space between gas particles is very much larger than in solids and liquids.
- Hence, using the particulate model of matter, it can be explained why gases do not have definite shape or definite volume. They can be easily compressed.
What happens when a substance in the solid state is heated?
• When a substance in the solid state is heated, its particles gain more kinetic energy and vibrate more vigorously about their fixed positions. The distances between the particles increase. This causes the volume of the substance to increase but its mass stays the same. Therefore, the substance gains heat and expands.
What happens when a substance in the solid state is cooled?
• Conversely, when a substance in the solid state is cooled, its particles lose more kinetic energy and vibrate less vigorously about their fixed positions. The distances between the particles decrease. This causes the volume of the substance to decrease but its mass stays the same. Therefore, the substance loses heat and contracts.
Does the number and size of particles change during expansion and contraction?
• Upon heating and cooling, the distances between the particles in a liquid and a gas change in a similar manner as those in a solid. This results in an increase or a decrease in the volume of the substance.
- The number and size of particles in a substance do not change during expansion and contraction. Thus, there is conservation of mass.
Melting
Gain Heat
Solid → Liquid From
regular, very closely packed to randomly packed and further apart
From vibrating about fixed positions to moving randomly and freely in all directions
When a solid is heated, its particles gain energy. They vibrate faster about their fixed positions. They eventually gain enough energy to overcome the very strong forces of attraction between them. Hence, the solid gains heat, melts and becomes a liquid.
Boiling
Gain Heat
Liquid → Gas
From random, closely packed to much further away from one another From moving randomly and freely in all directions to moving at faster speeds
When a liquid is heated, its particles gain energy. They move faster and further apart from one another. They eventually gain enough energy to overcome the strong forces of attraction between them. Hence, the liquid gains heat, boils and becomes a gas.
Freezing
Lose Heat
Liquid → Solid
From random, further apart to regular and closely packed
From moving randomly and freely in all directions to become vibrating in fixed positions
When a liquid is cooled, its particles lose energy and move slower. This causes the particles to be pulled much closer to one another by the forces of attraction between them. The particles are eventually held in fixed positions. Hence, the liquid loses heat, freezes and becomes a solid.
