Matter & Energy Interactions
What happens to particles when something gets hotter?
They move faster and spread apart.
If you tear a piece of paper in half, does the total weight change?
No.
What kind of change happens when you stir sugar into water?
A physical change — no new substance is formed.
What happens to most materials when they get hot?
They expand.
Why does a metal spoon feel hotter than a wooden one in hot soup?
Metal conducts heat better than wood.
What happens to particles when something cools down?
They slow down and move closer together.
When water freezes into ice, does its weight change?
No, it’s still the same amount of water.
What does it mean when vinegar and baking soda bubble?
A new substance (gas) was formed — a chemical change.
What happens to most materials when they get cold?
They contract.
Why do some pots have metal bottoms but plastic handles?
Metal conducts heat to cook food; plastic handles stay cool to touch.
If a solid turns into a liquid, what kind of change is that? (physical or chemical)
A physical change.
If you burn a piece of wood, where does some of its matter go?
Into the air as gases like smoke and carbon dioxide.
What clues tell you a new substance has been made?
A color change, gas bubbles, temperature change, or a new smell.
Why do sidewalks have small gaps between each section?
To give the concrete room to expand on hot days.
Why do roads crack after hot days and cold nights?
The pavement expands in heat and contracts in cold, causing cracks.
How do we know heat is being transferred between two objects? Think: how does heat move?
Heat always moves from the warmer object to the cooler one.
How can we prove matter is conserved in an experiment?
By measuring weight before and after — it stays the same.
Is mixing salt and pepper a physical or chemical change?
A physical change — you can separate them again.
Why do we wear light-colored clothes in summer?
Light colors reflect heat and keep us cooler.
Why do some metals heat up faster than others?
Different metals absorb and conduct heat at different rates.
Why does an ice cube melt faster in warm water than in cold water?
Warm water has more heat energy to transfer to the ice cube.
Why does a balloon filled with air weigh more than an empty one?
Because air is matter and has mass.
Why does a rusted nail show a chemical change?
The metal reacts with oxygen and becomes a new substance (rust).
Why do power lines sag in summer and tighten in winter?
Heat makes them expand, and cold makes them contract.
How do engineers test materials before building something?
They heat and cool them to see how they expand, contract, and stay strong.