Podcast
Questions and Answers
What happens to the particles of a substance when temperature increases?
What happens to the particles of a substance when temperature increases?
- They move slower and become closer together.
- They move faster and become further apart. (correct)
- They collapse into a solid state.
- They remain stationary.
A higher density substance will float in a liquid with lower density.
A higher density substance will float in a liquid with lower density.
False (B)
What is density and how is it calculated?
What is density and how is it calculated?
Density is the mass per unit volume of a substance.
When the temperature increases, the density of a substance __________.
When the temperature increases, the density of a substance __________.
Match the following properties to their definitions:
Match the following properties to their definitions:
What was the main observation made by Robert Brown in his experiment?
What was the main observation made by Robert Brown in his experiment?
Albert Einstein did not provide an explanation for Brownian motion.
Albert Einstein did not provide an explanation for Brownian motion.
What term is used to describe the random movement of pollen grains observed by Robert Brown?
What term is used to describe the random movement of pollen grains observed by Robert Brown?
In his observation, Robert Brown noticed that pollen grains appeared to be moving randomly due to the movement of ______.
In his observation, Robert Brown noticed that pollen grains appeared to be moving randomly due to the movement of ______.
Match the following individuals to their contributions:
Match the following individuals to their contributions:
Flashcards
What is density?
What is density?
The amount of matter packed into a given space. Measured as mass per unit volume.
What happens to particles when a substance is heated?
What happens to particles when a substance is heated?
When heated, particles move faster and spread further apart. This makes the substance expand.
How does density change with temperature?
How does density change with temperature?
Density decreases as temperature increases. This is because the particles spread out, making the substance less dense.
How does density affect floating and sinking?
How does density affect floating and sinking?
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How does a Galileo thermometer work?
How does a Galileo thermometer work?
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Brownian Motion
Brownian Motion
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Democritus
Democritus
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Particles
Particles
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Albert Einstein
Albert Einstein
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Robert Brown's Discovery
Robert Brown's Discovery
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Study Notes
Matter as Particles
- Matter is anything that has mass and takes up space
- All matter is made up of particles
- The main points of particle theory are summarized in the particle theory
- Particle theory:
- All matter is made up of particles
- Particles are very small
- There are empty spaces between particles
- Particles are moving all the time
- Different matter is made up of different particles
- Different particles have different sizes and masses
- Scientists have used experiments to support the particle theory
- Atoms are the basic types of particles that make up matter
- Molecules consist of two or more atoms joined together chemically
- A chemical formula of a molecule shows the types and the number of atoms in a molecule.
- For example: Hâ‚‚O (water molecule)
States of Matter
- Matter exists in three states: solid, liquid, and gas
- These states have different properties
- Solids:
- Have a fixed shape
- Cannot be compressed readily
- Liquids:
- Do not have a fixed shape
- Take on the shape of their container
- Cannot be compressed readily
- Gases:
- Do not have a fixed shape
- Take on the shape of their container
- Can be compressed readily
Dissolving
- When a solid dissolves in water, the solid's particles separate and mix with the water particles
- The resulting mixture is a solution.
- The dissolved substance is called the solute. Water is the solvent in this case.
- The mass of the resulting solution is equal to the combined mass of the solute and solvent.
- Volume of the solution may be slightly smaller than the combined volume of the solute and solvent, due to space between particles.
Thermal Expansion and Contraction
- Heating causes particles to move faster and spread out further, which increases the size of a substance. This is called thermal expansion.
- Cooling causes particles to move slower and come closer together, which decreases the size of a substance. This is called thermal contraction.
Gas Pressure
- Gas pressure is caused by gas particles hitting the walls of the container.
- Gas pressure increases with temperature as particles move faster and hit the container walls more often.
- Gas pressure increases when the volume (space) of the container is decreased as gas particles hit the container walls from a smaller space more frequently.
Density
- Density: mass per unit volume
- Density = mass / volume (in g/cm³ or kg/m³)
- Objects with higher density have more mass for a given volume.
- Whether objects float or sink depends on their density compared to the liquid they are in.
- Objects with lower densities will float, objects with higher densities will sink.
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