U1- Module 2: Modeling of Matter Flashcards
When does pressure become present?
When a collision occurs between molecules
What effect does increasing the temperature have on the pressure?
Increases pressure
What effect does increasing the number of molecules have on the pressure?
Increases pressure
What effect does increasing the volume have on the pressure?
Decreases pressure
What effect does the mass of particles have on pressure?
No effect
Particulate Model of Matter
Explains and predicts the physical properties and behavior of substances.
What are the 2 assumptions of the particulate model of matter?
- Any large sample of a substance is made of a larger number of very small particles.
- Particles are constantly moving in random directions through empty space.
How many particles are in 1 mL of water?
3.34 x 10^22
How big is a particle of water?
Nanometer size (1 x 10^-9)
Pressure
The force of the particle collisions on the walls
Pressure Formula
Pressure = force/area
How is macroscopic energy measured?
Due to microscopic collisions
Temperature
A measure of the average kinetic energy per particle.
What increases temperature?
Addition of energy
What effect does mass have?
Inversely effects velocity
- increase; decrease volume
etc.
Does mass effect the energy levels?
No
The lower the mass…
The higher the velocity (speed)
Volume and amount of particles are…
Directly proportional
Temperature and volume are…
Directly proportional
What are the only 2 variables that are inversely proportional?
Pressure and volume
What happens to potential energy when you strengthen intramolecular forces?
Potential energy decreases
How does temperature and pressure affect intramolecular forces?
- Increasing pressure increases the forces
- Increasing temperature decreases the forces (more likely to move apart)
What happens to the average kinetic energy when water evaporates?
It doesn’t change
What are the ideal gas law conditions?
High temperature and low pressures
What is true of the quantities in the ideal gas law?
None of them depend on the chemical composition of the actual system.
What happens when there are intramolecular forces when the temperature is low?
The particles begin to cluster/stick together
What is the 3rd basic assumption of the particulate model of matter?
Particles interact with each other. The strength of the interactions depends on the distance between particles.
What happens to interactions and physical states at different distances?
Low: Repel; solid
Medium: Strong attraction; liquid
High: Small/no attraction; gas
What happens to the average kinetic energy when temperature decreases?
It decreases
What does a phase change always involve?
A change in how matter and energy are distributed in a system.
Kinetic Energy
Due to particle motion
Potential Energy
Due to particle interactions (energy stored)
What value does potential energy start at?
0
As particles become closer, what happens to the level of the potential energy?
It decreases (becomes negative)
Why does potential energy have a negative value?
The attractive forces (kinetic energy) are doing the work of bringing the particles together
lower potential for particles to come together now (already happened)
Do larger or smaller particles have a stronger attraction?
Larger
What does lower potential energy levels mean?
A more stable configuration; stronger bond
What does a phase change always involve?
A transition in how matter and energy are distributed in a system.
What is the formula for kinetic energy?
KE = 1/2 mv^2
How do you get rid of attractive forces?
Add energy to overcome the phase change
How do you convert from a gas to. a liquid?
Remove energy to move the particles closer together.
What happens to the average KE of a particle during a phase change?
It stays constant (no change)
- same pattern as temperature
What are the 2 competing phenomena in the environment?
- Particles constantly move in random directions.
- There are attractive interactions between particles.
What are the 2 critical elements that must be analyzed to understand system changes?
- Potential energy of its particles
- Number of configurations particles can adopt.
What is the outcome of the competition of a system dependent on?
- Strength of interactions
- Factors that impact movement of particles.
What is the relationship between relative potential energy and particle distance?
The farther apart particles are, the higher potential energy they have.
What phase is the potential energy highest?
Solid - repulsive attractions
What phase is the potential energy lowest?
Liquid - most stable phase
What is the relationship between distance and potential enegry?
The greater the distance between particles, the higher the potential energy level.
What phase has the most number of particle configurations?
Gases; more distance between particles
What factor is likely to induce a phase change to the gaseous state?
Random motion
What are the characteristics of liquids in PEC diagrams?
- Low potential energy
- Low number of configurations
What are the characteristics of gases in PEC diagrams?
- High potential energy
- High number of configurations
What are the phase changes in PEC diagrams dependent on?
- Temperature
- Pressure
What phase state is favored at high temperatures?
Gas
- The higher the temp, the higher the Pe
- Allows the system to absorb the energy needed to change to the gaseous phase
What phase state is favored at lower pressures?
Gas
- Higher pressure favors higher number of particle configurations
- Particles have more freedom to adopt configurations
What phase is favored at higher pressures and lower temperatures in PEC diagrams?
Liquids
What phase is favored at lower pressures and higher temperatures in PEC diagrams?
Gases
