Units 12-13 Flashcards
Properties of matter (in this class):
- Physical state at room temperature
- Temperatures at which they CHANGE states
- Density in various physical states
- Response to different types of force
- Color
- Whether they conduct electricity
What are the four states of matter?
Liquid, solid, gas, plasma
Solid
Rigid with a fixed volume and shape.
What size of force is required to change the shape of a solid?
Large force
Liquids
Not rigid and change shape when poured from one container to another.
The volume of a liquid DOES NOT CHANGE when the shape of container changes.
Gases
Not rigid, nor are their volumes fixed. Gases move from container to container, adopting the shape of the new container and expanding or contracting to fill its volume.
Plasma
A gas of positively and negatively charged particles. The positive particles are atoms that have lost their electrons. The negative particles are the electrons that were lost.
Fluid properties.
What is the most common form of matter in the universe?
Plasma
Examples of plasma
Northern lights, solar winds (blowing off the sun), and fluorescent lightbulbs
True or False: There are materials that do not fully fall into a single one of the four categories of matter.
True
Like Jello or silly putty
What is the only known substance that does NOT form a solid just by cooling?
Helium
Must have strong pressure too
True or False: Large changes of density occur when a material undergoes a change of state
True
True or False: Generally, solids are the most dense
True
True or False: Liquids are much denser than gas
True
Compression force
A force that is applied to COMPRESS a material
Pushing force
Tension force
A force that pulls at something (pulls apart) or creates tension
Pulling force
Shear force
A twisting or deforming force
True or False: Compression waves and shear waves are caused by compression and shear forces, respectively.
True
How does tension force play a role in waves?
It pulls material back to its equilibrium point.
True or False: Solids can sustain or “support” all three types of forces
True
What does “support” mean?
Resists the force applied
True or False: Liquids can “support” compression and tension forces, but NOT shear forces.
True
What is the ONE type of force that a gas can “support”?
Compression
Electromagnetic spectrum
The entire range of radiation including cosmic-ray photons, gamma rays, x rays, UV, visible light, infrared, microwaves, and radio waves.
What is white light?
All the colors combined together.
What determines the overall color of an object?
The portions of the spectrum that an object can absorb or reflect.
How is color related to the internal structure of the material?
Colors tell us there is something DIFFERENT about the two materials.
If they were the same, their color would be identical.
Why does bright sunlight appear white?
Because it is giving off ALL colors of the rainbow!
Continuous spectrum
Giving off all the colors that blend together to create white light (like the sun, the sun gives off a continuous spectrum).
True or False: ALL materials give off light when they are heated to high temperatures.
True
Discrete spectra
A spectrum of separate and distinct colors in which not all colors are present.
Like gases that only give off a few colors of light when heated.
True or False: The spectrum of colors that a material gives off is distinctive and can be used to identify it.
True
True or False: Metals in a solid or liquid state ALWAYS conduct electricity
True
Ionic conductor
Material that does not conduct electricity in the solid state, but do when molten or dissolved in water
Example of ionic conductor
Salt
Non-conductor
A material that does not conduct electricity in ANY of its physical states.
Examples of non-conductors
Sugar and ethanol
What is the boiling point?
The temperature at which a material boils.
What is the boiling TEMPERATURE?
The temperature of boiling at which a substance CHANGES from a liquid to gas or vice versa
What is the melting point?
The temperature at which a material melts
What is the melting TEMPERATURE?
The temperature at which a substance CHANGES from a solid to liquid or vice versa
What is plasma?
It is a material that is so hot the particles no longer stick together but move independently of each other.
Why does plasma glow?
Because the charges are separate in plasma, they accelerate and release electromagnetic radiation.
True or False: The melting and boiling points of a material correlate (low melting point = low boiling point, etc.).
TRUE
What is a scientific model?
A tool we use to explain why nature behaves as it does.
Why do scientists use models when studying matter?
Because the fundamental particles are too small to obtain direct or exact measurements. It’s difficult or impossible to do so. So we use models to predict.
What determines if a model is successful?
If it correctly predicts what will happen
How many assumptions are part of the molecular model?
4
What are the four assumptions of the molecular model?
- Matter consists of tiny particles called molecules.
- Each different kind of matter consists of a different kind of molecule.
- Molecules in matter are in constant motion
- Molecules move and interact in accordance with laws of motion, force, and conservation
What are molecules?
They are the smallest possible fundamental/building block that retains all the physical properties of a substance.
True or False: The differences between the molecules primarily create the different physical properties of each substance.
True
True or False: Molecules NEVER stop moving
True
True or False: Molecules regularly approach speeds that require the laws of relativity to be enforced.
FALSE
What is Brownian motion?
The random motion of particles such as dust or pollen in a liquid when viewed with a microscope.
How are the molecules in a solid packed?
So close together they almost touch.
How are molecules in a liquid arranged?
Not packed by still relatively close.
How are molecules in a gas arranged?
Only in contact with each other when they collide
True or False: In a solid, molecules vibrate in place because they’re all so close together
True
True or False: Molecules in liquids are not completely free of the attraction of neighboring molecules even they they are free to move around within their container.
True
True or False: Collisions between molecules can happen in solids.
FALSE
What does the potential energy of a molecule depend on?
How close they are to other molecules
True or False: Molecules ALWAYS have kinetic energy
True, because they’re always moving
What did Maxwell do for molecular theory?
Developed a model and formula that lets us calculate the fraction of molecules going a particular speed if we know the mass of the molecules and the temperature of the gas.
What happens to molecules as the temperature increases?
They move faster on average and have a wider range of speeds.
True or False: Maxwell’s equation says that the average kinetic energy of all gases will be the same at the same temperature.
True
True or False: Gas molecules that are smaller in mass will move at FASTER speeds than larger molecules
True
What is the rule of temperature and molecules of any state of matter?
For matter in any state, temperature is a measure of the average kinetic energy of the molecules.
Higher heat = faster speed (more kinetic energy)
True or False: Liquids have higher potential energy than solids
True
What happens to the potential energy of molecules when additional energy is inputted?
It increases
Rank the potential energy of different matter states from least to greatest:
LEAST: Solids
Middle: Liquids
MOST: Gases
Rank the kinetic energy of different matter states from least to greatest:
LEAST: Solids
Middle: Liquids
MOST: Gases
Does heat increase, decrease, or stay the same when two states of matter are present (changing between states)?
THE SAME
In which direction does heat energy flow?
From hot to cold
What is gas pressure?
The sum of the collective force exerted by many gas molecules colliding over a given area at the same time (gas inside a container will always have some level of pressure)
Does gas pressure increase or decrease as temperature increases?
Increase
Why do molecules move apart with higher heats?
The heated molecules move more, causing greater jiggling. This jiggling covers more space, so the molecules move apart to accommodate the expanded motion.
True or False: Faster moving gas molecules hit the walls of their container more frequently, contributing to higher gas pressure.
True
What is the general rule of attraction between molecules?
They DO attract.
