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@openstem · Joined Jul 2026
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01Chemistry · L5 · Ultrafast Femtochemistry
02Chemistry · L5 · Ultrafast Femtochemistry
03Chemistry · L5 · Ultrafast Femtochemistry
+1 moreChemistry · L5 · Ultrafast Femtochemistry
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Chemistry · L5 · Ultrafast FemtochemistryCollection3 items
01Chemistry · L5 · Zeolite Catalysis
02Chemistry · L5 · Zeolite Catalysis
03Chemistry · L5 · Zeolite Catalysis
Chemistry · L5 · Zeolite Catalysis
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Chemistry · L5 · Zeolite CatalysisFlashcards5 cards
What is a solid?1 / 5
A solid keeps its own shape. A brick, an apple, and a pencil are all solids.
Chemistry · L1 · Solids, Liquids, and Gases
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Chemistry · L1 · Solids, Liquids, and GasesFlashcards5 cards
What happens when you stir sugar into water?1 / 5
The sugar disappears into the water. We say it dissolves. The water tastes sweet.
Chemistry · L1 · Mixing and Dissolving
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Chemistry · L1 · Mixing and DissolvingFlashcards8 cards
What happens to egg white when you cook it?1 / 8
It turns from clear and runny to white and firm. It can never go back to being runny again — that's a chemical change.
Chemistry · L1 · Everyday Chemical Changes
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Chemistry · L1 · Everyday Chemical ChangesFlashcards8 cards
What is a metal?1 / 8
A metal is shiny and hard. Spoons, coins, and nails are made of metal.
Chemistry · L1 · Metals and Non-metals
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Chemistry · L1 · Metals and Non-metalsFlashcards7 cards
Is a spoon a metal or a non-metal?1 / 7
Metal! A spoon is shiny and it bends a little instead of snapping.
Chemistry · L1 · Sorting Everyday Objects
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Chemistry · L1 · Sorting Everyday ObjectsFlashcards11 cards
What does it mean when something floats?1 / 11
It means the object stays on top of the water instead of going under.
Chemistry · L1 · Floating and Sinking
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Chemistry · L1 · Floating and SinkingFlashcards8 cards
What happens to chocolate when it gets warm?1 / 8
It melts! Warm chocolate turns from a hard bar into a smooth, runny liquid.
Chemistry · L1 · Heating and Cooling Food
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Chemistry · L1 · Heating and Cooling FoodFlashcards7 cards
Why do we keep milk in the fridge?1 / 7
The cold keeps milk fresh for longer. Without the fridge, milk would spoil much faster.
Chemistry · L1 · Fridges, Freezers, and Staying Safe
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Chemistry · L1 · Fridges, Freezers, and Staying SafeFlashcards8 cards
What is in a fruit salad?1 / 8
A fruit salad has different fruits mixed together, like apple, banana, and grapes.
Chemistry · L1 · Food Mixtures
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Chemistry · L1 · Food MixturesFlashcards7 cards
What happens when you blend fruit into a smoothie?1 / 7
The fruit gets mashed up smooth. It looks different, but it is still just mixed-up fruit.
Chemistry · L1 · Blending, Painting, and Dressing
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Chemistry · L1 · Blending, Painting, and DressingFlashcards10 cards
What happens to most liquids when they freeze?1 / 10
Most liquids get heavier and sink when they freeze into a solid.
Chemistry · L1 · Water, a Special Liquid
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Chemistry · L1 · Water, a Special LiquidFlashcards10 cards
What does it mean when a material is natural?1 / 10
It means the material grows or is found in nature, without people making it. Wood, cotton, and stone are all natural.
Chemistry · L1 · Natural and Human-made Materials
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Chemistry · L1 · Natural and Human-made MaterialsFlashcards8 cards
You find a bottle you don't know. Should you taste what's inside?1 / 8
No, never! Some bottles hold chemicals that can hurt you. Only taste food and drinks you know are safe.
Chemistry · L1 · Staying Safe with Chemicals
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Chemistry · L1 · Staying Safe with ChemicalsFlashcards6 cards
What is a hazard symbol?1 / 6
A hazard symbol is a picture on a bottle. It warns you that what's inside could hurt you.
Chemistry · L1 · Warning Pictures on Bottles
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Chemistry · L1 · Warning Pictures on BottlesFlashcards10 cards
What does it mean to recycle something?1 / 10
It means turning something old and used into something new, instead of throwing it away forever.
Chemistry · L1 · Sorting and Recycling Materials
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Chemistry · L1 · Sorting and Recycling MaterialsFlashcards10 cards
Why does a sliced apple turn brown?1 / 10
Air touches the inside of the apple where it was cut. That slowly turns the flesh brown.
Chemistry · L1 · Colors That Change
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Chemistry · L1 · Colors That ChangeFlashcards10 cards
Can you see the air around you?1 / 10
No, air is invisible. You cannot see it, but it is all around you, all the time.
Chemistry · L1 · Air, Breathing, and Gases
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Chemistry · L1 · Air, Breathing, and GasesFlashcards12 cards
What makes the bubbles in a fizzy drink?1 / 12
A gas called carbon dioxide is squeezed into the drink. When you open the bottle, some of it escapes as bubbles.
Chemistry · L1 · Fizzy Drinks and Dissolved Gas
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Chemistry · L1 · Fizzy Drinks and Dissolved GasFlashcards10 cards
What happens if you leave a cup of salty water out for many days?1 / 10
The water slowly disappears into the air. Salt crystals are left behind at the bottom of the cup!
Chemistry · L1 · Growing Crystals at Home
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Chemistry · L1 · Growing Crystals at HomeFlashcards11 cards
Why does bread dough puff up in the oven?1 / 11
Tiny bubbles of gas get trapped inside the dough. As the bubbles grow, they push the dough up and make it puffy.
Chemistry · L1 · Why Bread and Cakes Rise
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Chemistry · L1 · Why Bread and Cakes RiseFlashcards10 cards
Can plain water wash grease off a pan?1 / 10
Not very well. Grease and water do not mix, so plain water just pushes the grease around instead of washing it away.
Chemistry · L1 · How Soap Cleans
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Chemistry · L1 · How Soap CleansFlashcards12 cards
What is a magnet?1 / 12
A magnet is a special object that pulls certain metals towards it, making them stick.
Chemistry · L1 · Testing with Magnets
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Chemistry · L1 · Testing with MagnetsFlashcards10 cards
What is a smell actually made of?1 / 10
A smell is made of tiny, invisible particles. They come off a substance and float through the air to your nose.
Chemistry · L1 · Where Do Smells Come From?
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Chemistry · L1 · Where Do Smells Come From?Flashcards10 cards
Why does a bike frame left outside all year get rustier than one kept in a garage?1 / 10
The bike left outside gets rained on and sits in damp air all the time. The metal almost never gets to dry out, so it rusts much faster.
Chemistry · L1 · Weathering: Why Outdoor Metal Rusts
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Chemistry · L1 · Weathering: Why Outdoor Metal RustsFlashcards11 cards
Why do people put salt on icy sidewalks in winter?1 / 11
Salt makes it much harder for water to stay frozen. The hard ice turns into slushy water, which is safer to walk on.
Chemistry · L1 · Why Salt Melts Icy Roads
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Chemistry · L1 · Why Salt Melts Icy RoadsFlashcards10 cards
What is invisible ink?1 / 10
It's a special "ink" that disappears once it dries on paper. You can make the message appear again later with a trick.
Chemistry · L1 · Secret Messages with Invisible Ink
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Chemistry · L1 · Secret Messages with Invisible InkFlashcards10 cards
What happens when you drop food colouring into a still glass of water?1 / 10
It slowly spreads out into curly, cloud-like tendrils until the whole glass is evenly coloured — with no stirring at all!
Chemistry · L1 · Why Food Colouring Spreads Through Water
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Chemistry · L1 · Why Food Colouring Spreads Through WaterFlashcards11 cards
What is different about the gas inside a helium balloon, compared to the air all around us?1 / 11
The helium gas is packed together much more loosely than the air around it — that is what makes the whole balloon float.
Chemistry · L1 · Why Helium Balloons Float Up
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Chemistry · L1 · Why Helium Balloons Float Up