Chemical Reactions
Imagine combining a toxic green gas with a metal that aggressively explodes when it touches water. It sounds like a recipe for a disaster! But as we are about to learn, when chemicals combine, their properties can change completely.
Can Two Deadly Poisons Make Something You Eat Every Day?
You get table salt! Bill Nye the Science Guy shows us that combining dangerous Sodium with poisonous Chlorine creates Sodium Chloride, which is perfectly safe to eat on your chips.
Just over a hundred elements! Much like a few letters can make thousands of words, these basic elements combine in different chemical reactions to make everything we know and love.
Put Your Instincts to the Test
Think about what you already know about the world around you. Pick an answer for each question, then see if your instincts were right.
It breaks apart into hydrogen and oxygen gases! Water is made of two chemicals bound together. As Bill Nye the Science Guy demonstrates, running energy through the water splits the H2O back into hydrogen and oxygen bubbles.
A chemical reaction takes in heat energy! When you crack the pouch, two chemicals mix. This specific reaction takes up more energy to happen than it gives off, so it sucks the heat right out of the athlete's injured leg.
Carbon dioxide gas bubbles! When baking soda reacts with water and heat, it creates thousands of tiny bubbles of carbon dioxide gas that rush up and make the cake light and spongy.
Understanding the Science
Tap each card to discover the fundamental rules of how chemicals interact, bond, and build the world around us.
Key Concepts
Chemicals
Tap to learn moreEverything you see, touch, and eat is made of chemicals. From the clothes you wear to the water you drink, the entire universe is constructed from these basic building blocks.
Chemical Reactions
Tap to learn moreThis happens when different chemicals interact and bond together to form an entirely new substance. A reaction changes the original chemicals into something completely different.
Electrons
Tap to learn moreThese are the tiny, negatively charged particles found inside every atom. Chemical reactions occur because the electrons from different chemicals hook together and recombine.
Elements
Tap to learn moreThese are the purest forms of chemicals. An element cannot be broken down into a simpler substance. Oxygen, iron, and carbon are all examples of elements.
The Periodic Table
Tap to learn moreThis is a famous chart used by scientists everywhere. It lists all the known elements and groups them together based on how they behave in chemical reactions.
Compounds
Tap to learn moreWhen two or more different elements chemically bond together, they form a compound. Water is a compound made of hydrogen and oxygen bonded perfectly together.
Exothermic Reactions
Tap to learn moreMany chemical reactions give off energy as they happen. When iron rusts or wood burns in a fire, heat and light energy are released into the surrounding area.
Endothermic Reactions
Tap to learn moreSome rare chemical reactions actually absorb energy from their surroundings instead of releasing it. This is exactly how instant cold packs work to chill an injury.
Try It: The Reaction Lab
You are the master chemist! Pick a reaction from the shelf, study the equation, then tap React! to see what happens. Each reaction will be classified by its type (synthesis, decomposition, combustion, or acid-base) and by whether it gives off energy (exothermic) or absorbs it (endothermic). How many can you discover?
Reaction Shelf (tap to load)
Discovery Log
Apply Your Knowledge
Let us see if you can connect these chemical concepts to their real-world examples.
Match the Concepts
Click an object to select it, then click the matching description to place it.
Real-World Challenge
Imagine you are camping and trying to start a campfire, but your logs are just smouldering and smoking without catching a bright flame. You remember Bill Nye the Science Guy explaining that fire is a chemical reaction. What invisible chemical from the air is missing from your reaction, and how could you change your fire pit to get more of it?
What Has Changed Since This Episode Aired
This episode aired in 1994. While the core rules of chemistry remain completely accurate, our understanding of some elements has expanded.
Updated: That was actually a slip of the tongue by the expert! Strontium is famous in chemistry for producing a brilliant, deep red colour when burned. If a fireworks designer wants a bright yellow explosion, they use the element Sodium instead.
Updated: While textbooks in the 1990s taught there were 92 naturally occurring elements, modern science confirms there are 94 found in nature (counting all the way up to Plutonium). Furthermore, scientists have now used modern physics to synthesise up to 118 confirmed elements in the laboratory!
Test Your Understanding
Answer these questions and get instant feedback. How many can you get right?
Results
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Reflection
Look around the room you are in right now. Choose one object and try to imagine the chemical reactions that had to happen in a factory or in nature to create it. What do you think its raw elements were?
Episode Discussion
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