B uildingBlocks o f Matter Everything in the world is made up of molecules Our bodies our clothes our houses animals plants air water sky everything Molecules are so small though that we can’t see them with our naked eyes But molecules aren’t the smallest things Molecules are made up of atoms which are smaller still Atoms are so small that it takes more than a billion atoms to fill the space taken up by one pea The word atom comes from the Greek word atomos meaning indivisible But despite what their name suggests atoms can indeed be divided into smaller pieces Each atom has a core called a nucleus Around the nucleus swarm small particles called electrons The nucleus itself is made up of other small particles called protons and neutrons And these protons and neutrons are made up of even smaller things called quarks So for now at least quarks are among the smallest known things in the universe LEARN MORE READ THESE ARTICLES ENERGY LIQUIDS SOLIDS AND GASES MARIE CURIE l DID YOU KNOW that scientists have to make up new ways to describe Quarks are so smal They talk about the different flavors of quarks not chocolate or them pistachio but up down charm strange top and bottom
ATOMS S EA R C H LIG H T True or false Atoms are the smallest things of all are even smaller than those protons all of which are smaller than the atom itself And quarks Answer FALSE Atoms can be split into electrons neutrons and 7
Same S t u f f nt Diffe r rms Did you know that many of the things you may see or use e F o every day such as the water in a glass the air in a football and even the hard metal in a toy car are potential shape-shifters The substances that these things are made of can have the form of a solid a liquid or a gas The form they take depends mostly on their temperature When water gets cold enough it becomes a hard solid we call ice When it gets hot enough it becomes a wispy gas we call steam Many other substances behave the same way when they are heated or cooled enough A solid holds its own size and shape without needing a container If you pour water into an ice tray and freeze it the water will keep the shape of the cube-shaped molds in the tray You can think of the solid metal in a toy car as frozen too but its melting temperature is much higher than the temperatures we live in The person who made the car poured very hot liquid metal into a car-shaped mold and let it cool down and freeze A liquid does not hold its own shape If you pour a measuring cup of water into a tall glass or a shallow bowl it will take the shape of its container But that water does keep its own size It measures one cup Everyday liquids such as milk paint and gasoline act this same way Gases do not keep their own shape or their own size When air is pumped into a football it takes the shape and size of the ball As more air is pumped in the ball gets harder but not much bigger The air changes its size to fit the space inside the ball LEARN MORE READ THESE ARTICLES ENERGY TEMPERATURES VOLCANOES 8
LIQUIDS SOLIDS AND GASES S EA R C H LIG H T Mark whether each item below describes a solid S a liquid L or a gas G Some may match more than one form melts turns into a liquid has no shape or size is frozen keeps shape has no shape DID YOU KNOW If you’ve ever smelled gas coming from a stove you know it has an odd odor But cooking gas has no odor What you’re smelling is another gas with an odor that’s easy to notice It’s mixed with the cooking gas so that people know when there’s a leak is frozen S has no shape L G keeps shape S has no shape or size G Answer melts S turns into a liquid S G 9
