Cynthia Light Brown - Kitchen Chemistry: Cool Crystals, Rockin Reactions, and Magical Mixtures with Hands-On Science Activities

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CHEMISTRY
MATTERS!

What makes something soft or hard? What makes something a solid, liquid, or gas? Why does water change from solid ice to liquid water to water vapor ? Chemistry can tell you! Chemistry is at the heart of how everything worksits the science of change.

You might think that chemists are people who work in labs and wear white coats. But thats not necessarily true! Chemistry is everywhere and chemistry can be studied everywhereincluding in your kitchen, classroom, and backyard. And anyone can explore chemistry with fun experiments and activities. The rule is to keep it safe.

ESSENTIAL QUESTION

What is chemistry?

WORDS TO KNOW

water vapor: the gas state of water.

chemistry: the study of the properties of substances and how they react with one another.

Chemistry is the study of matter and how it changes. Matter is anything that has mass and takes up space. That means everything on Earth, in the solar system, and in the galaxy is made of matter. Including you! What about the book or tablet you are holding? What about your dog? What about the water youre drinking? What about the air youre breathing?

MATTER
its all matter!

Matter is made up of atoms and molecules , known as the basic building blocks of matter. Think of a bucket full of water. This bucket contains more molecules of water than there are buckets of water in the entire Atlantic Ocean! Atoms are pretty small.

WORDS TO KNOW

matter: anything that has weight and takes up space. Almost everything is made of matter!

atom: the smallest particle of matter that cannot be broken down by chemical means. An atom is made up of a nucleus of protons and neutrons surrounded by a cloud of electrons.

molecule: a group of atoms bound together to form matter.

solid: one of the three states of matter. The particles in a solid are bound together tightly. A solid has a definite shape and volume and does not flow.

liquid: one of the three states of matter. The particles in a liquid cluster together and flow. A liquid has a definite volume, but takes the shape of its container.

gas: one of the three states of matter. The particles in a gas are not bound to each other and move very fast in all directions. A gas does not have a definite shape or volume.

interact: how things act when they are together.

States of Matter

There are three common states of matter: solid , liquid , and gas . With enough heat or cooling, a substance can change from one to another. A good example is liquid water, which when heated can change into water vapor, or if cooled can change into ice. Ice can melt back into water and water vapor can cool to change back into liquid water. When you see water droplets form on the outside of your cold glass of lemonade on a hot summer day, thats an example of water vapor changing into liquid water.

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THE MIND OF A SCIENTIST

Scientists have a special way of looking at the world, and you can, too. Heres what you do. Notice things. Pay attention. Look around. Be curious. Thats it. Thats the secret to being a scientist.

If Benjamin Franklin (17061790) hadnt noticed how the water changed behind ships as they sailed, he wouldnt have experimented with oil and water (see to learn more). If you notice whats going on around you, youll see all kinds of things to explore.

Water as a solid, liquid, and gas

credit: Ajith Kumar (CC BY 2.0)

WORDS TO KNOW

expand: to spread out and take up more space.

substance: the physical material from which something is made.

volume: the amount of space inside an object.

carbon: a kind of atom that is the building block of most living things, as well as diamonds, charcoal, and graphite.

Water EXPANDS as it freezes, which is different from most other substances . An ice cube takes up about 9 percent MORE VOLUME than the water used to make it.

If you see something you dont understand or that doesnt make sense, find out more about it. That may involve some research in a library, but it might also involve trying an experiment, which is another importantand even more funway to investigate. Ask questions such as Why? and What would happen if?

After you try an experiment or a project in this book, you can also change the experiment a bit to see what happens. Note that if you want to use new materials, though, check with an adult first to make sure the experiment will be safe.

Heres the important thing about making changes in a project: Only make one change at a time. Otherwise, you wont know which of your changes made a difference in the results.

Boiling water freezing almost instantly

credit: Alfredo Ristol (CC BY 2.0)

Watch a video about the buckyball! Well learn more about carbon later in the book. Is it surprising to you that major scientific discoveries are still being made? In fact, there are incredible breakthroughs in science every day. Maybe youll be the next person to make one!

Scishow buckyball

Believe what you see, not what you think you should see. If Erasto Mpemba (1950 ) hadnt believed his own eyes, he never would have figured out that boiling water can freeze faster than warm water (read about him in ). When you try an experiment or make a change to one youve already done, try to predict what might happen next.