What's the Matter?
What is the smallest unit of an element that still has the properties of that element?
What is an atom?
You put sugar in water and stir until it disappears. Did a chemical reaction occur? Why or why not?
What is no, because the sugar is still there and could be recovered by evaporating the water?
You burn a log in a fireplace. Why does it seem like mass is lost?
What is the mass turns into gas and ash, but the total amount of matter stays the same?
Why does breaking a tablet into pieces make it dissolve faster?
What is because it increases surface area, allowing more particles to react at once?
Why does salt help melt ice on the road in winter?
What is because it lowers the freezing point of water, causing the ice to melt?
Water (H₂O) is made of hydrogen and oxygen. Why is water a compound and not just a mixture?
What is because the atoms are chemically bonded together, forming a new substance with different properties?
A student cuts an apple in half. After a few minutes, the apple starts turning brown. What type of change is happening, and why?
What is a chemical change? Oxygen reacts with compounds in the apple, causing oxidation.
If a chemical reaction takes place in a sealed container, how does the total mass before and after compare?
What is it stays the same because mass cannot be created or destroyed?
A glow stick is placed in warm and cold water. Which one glows brighter and why?
What is the one in warm water because heat speeds up the reaction?
Why do some metal objects rust over time while others don’t?
What is because some metals, like iron, react with oxygen and water, while others, like aluminum, form a protective layer?
You have a sample of pure gold (Au) and a glass of saltwater. One is an element, and the other is a mixture. How do you know which is which?
What is gold is made of only one type of atom (element), while saltwater has multiple substances mixed together?
If a substance changes color when mixed with another but stays the same in every other way, does this prove a chemical reaction? Why or why not?
What is not necessarily—color change is a clue, but you need more evidence like gas formation or heat change?
A student sees bubbles forming in a test tube but notices the mass of the system stays the same. How is this possible?
What is because the gas produced still has mass, even if it spreads out?
You mix two chemicals together, and the reaction is very slow. What are two ways to speed it up?
What is increasing temperature, stirring, using smaller particles, or increasing concentration?
Many instant ice packs get cold when activated. Where does the energy go?
What is the reaction absorbs heat from the surroundings, making it feel cold?
A scientist discovers a new substance that can be broken down into two different elements. Is it an element, a compound, or a mixture? Explain.
What is a compound, because it can be separated into simpler substances?
A glass of soda fizzes when you open it. Is this a chemical change? Explain.
What is no, because the gas was already in the liquid and just escaping due to pressure change?
A factory burns fuel to generate energy. If energy is never destroyed, where does it go?
What is it transforms into heat and light energy?
In some reactions, adding too much of one reactant doesn’t make the reaction faster. Why?
What is because the other reactant is the limiting factor, meaning it runs out first?
If a battery is left in a device for too long, it may start leaking. What chemical reaction is likely happening?
What is a breakdown of the chemicals inside, releasing acidic or corrosive substances?
How can you tell if a substance is a molecule but not a compound? Give an example.
What is if it contains two or more of the same type of atom bonded together, like oxygen gas (O₂), which is a molecule but not a compound?
When a liquid is heated, it thickens and turns dark brown. No bubbles or gas are seen. Could this be a chemical reaction? Explain your reasoning.
What is yes, because the change in texture and color suggests a new substance formed, like caramelizing sugar?
If you mix two chemicals and the temperature suddenly drops, where did the energy go?
What is it was absorbed by the reaction, making it endothermic?
A scientist wants to slow down the reaction that causes food to spoil. What are some ways to do this?
What is lowering the temperature, reducing oxygen exposure, or using preservatives?
A company wants to create a portable heater using a chemical reaction. What type of reaction should they use and why?
What is an exothermic reaction because it releases heat?