Matter, Density & Temperature
A student puts a metal spoon and a plastic spoon in hot soup. The metal spoon feels hotter faster.
What is: Metal transfers heat faster? Different materials react differently to heating and cooling.
When matter is heated, what happens to particle movement and spacing?
What is particles move faster and spread farther apart?
How does a liquid thermometer measure temperature?
What is by expansion and contraction of a liquid?
Give two real world examples of expansion and contraction.
answers will vary
A jar is filled with air. The lid is tightly closed. The jar feels empty.
Using particle theory, explain why the jar is NOT empty.
What is: Air is made of particles that have mass and take up space, even though we cannot see them?
A balloon left outside on a cold winter day becomes smaller.
Why does this happen?
What is: The gas particles move slower and take up less space when it is cold?
When matter cools, why do particles move closer together?
What is attractive forces between particles increase?
Why does the liquid rise in a thermometer when heated?
What is the liquid expands as particles move faster?
Water is unusual because its solid form has ______ volume than its liquid form.
What is greater volume?
Water boils at 100°C.
Would this number be higher or lower in Kelvin? Explain.
What is: Higher, because Kelvin starts at absolute zero, so 100°C is 373 K?
A wooden block floats in water but sinks in oil.
What does this tell you about the densities of the three substances?
What is: The block is less dense than water but more dense than oil?
During a phase change, what happens to mass and volume?
Answer: What is mass stays the same but volume may change?
Why are 0°C and 100°C important on the Celsius scale?
What is they are the freezing and boiling points of water?
Why does ice float on water?
What is it is less dense than liquid water?
A sealed balloon is placed in a freezer. It shrinks. Later it is placed in warm water and expands.
Explain this using particle movement.
What is: Cold makes particles move slower and closer together; heat makes them move faster and spread out?
A thermometer reads 25°C. Later, it reads 5°C.
What likely happened to the movement of the particles?
What is: The particles slowed down?
Why does heating weaken the attractive forces between particles?
What is faster movement makes particles pull away from each other?
A thermometer reads –5°C. What is happening to particle motion compared to 20°C?
What is particles are moving slower at –5°C?
Why does ice on a lake help fish survive in winter?
What is the ice forms an insulating layer that protects the water below?
A metal object sinks in water but floats in a thick salt solution.
What does this tell you about density?
What is: The object is more dense than water but less dense than the salt solution?
Two containers hold the same amount of water. One is tall and skinny. The other is short and wide.
Which one has more mass?
What is: They have the same mass?
A student heats a metal rod. It becomes slightly longer.
Use particle theory to explain why.
Answer: What is particles move faster and spread apart, causing expansion?
A city builds a metal bridge without expansion gaps.
Explain what could happen during summer and winter using particle theory.
What is in summer the metal expands as particles move faster and the bridge could bend or crack; in winter it contracts as particles move slower?
Why are gaps placed between sections of bridges or sidewalks?
What is to allow for expansion and contraction due to temperature changes?
A syringe is filled with air and the tip is covered. When pushed, the air compresses.
Why can gas compress but liquids cannot easily?
What is: Gas particles are far apart, but liquid particles are close together?