Chemistry · High School (9–10)

Look around you. A stone, a glass of water and the air that you breathe are all matter, and they are very different. Why is a stone hard, water runny and air invisible? In this chapter we study the tiny particles that matter is made of. We find how they explain the solid, liquid and gas states, how ice melts and water boils, and why wet clothes dry and sweat cools us. Python helps us with the calculations.

A shop sells pure milk, pure butter and pure honey. Is the milk that you drink really pure in the way a chemist uses the word? In this chapter we learn what scientists mean by a pure substance, and how it differs from a mixture. We study solutions, suspensions and colloids, and the ways to separate the parts of a mixture. Then we meet the elements and the compounds that everything is made of. Python helps us with the calculations.

Burn a candle, and the wax seems to disappear. Does matter really vanish in a chemical change? In this chapter we meet the two laws that scientists found by weighing before and after a reaction. They lead us to the atom, the tiny particle that every element is made of. We learn how atoms join to form molecules and ions, how to write a chemical formula, and how chemists count atoms with a unit called the mole. Python helps us with the calculations.

In the last chapter the atom was the smallest piece of an element that we counted. But is the atom really the end of the road? In this chapter we open it up. We meet the three particles inside it, and we follow the experiments that gave us the nucleus. We learn how the electrons are arranged in shells, why this decides how an atom combines with others, and why two atoms of the same element can have different masses. Python helps us with the counting.

An iron gate turns brown, milk turns sour, and a match bursts into flame. In each case, new substances are made. In this chapter we learn how to see a chemical reaction, how to write it as an equation, and how to balance the equation. Then we meet the main types of reactions, we see which ones give out heat, we find out why iron rusts, and we calculate how much of a substance a reaction makes. Python helps us to balance and to count.

Lemon juice is sour. Soap feels slippery. Both are in your kitchen, and they are very different. In this chapter we learn how to tell an acid from a base, what they do to metals and to each other, and what they have in common when they are in water. Then we meet the salts that they make, from the salt on your plate to baking soda and plaster of Paris. We measure acidity with the pH scale, and we use it to understand the stomach, the teeth and the soil. Python helps us with the numbers.

A copper wire, an iron nail, a gold ring and a lump of coal are all made of elements, and they are very different. In this chapter we sort the elements into metals and non-metals, and we see how their properties differ and where the exceptions are. We learn how metals react with oxygen, water and acids, and how the reactivity series puts them in order. Then we find out how a metal and a non-metal join to make an ionic compound, and how metals are got from their ores. Python helps us with the numbers.

Food, clothes, medicines, plastics, fuels and your own body are all made of carbon compounds. There are more than ten million of them, and only a few of the other elements can make even a thousand. In this chapter we learn why carbon is so special: how it shares electrons, how its atoms join in chains and rings, and why diamond and graphite are so different. Then we learn the families of carbon compounds, how to name them, how they burn and react, and how ethanol, ethanoic acid and soap are made and used. Python helps us with the counting.

There are more than a hundred elements. How can anyone remember them all? A chemist does not. A chemist reads the periodic table, a chart that puts each element where its properties are easy to guess. In this chapter we see how the first lists were made, how Mendeleev left gaps for elements that nobody had found, and how the modern table is built on the electrons of an atom. Then we use the table to predict size, valency, reactivity and the nature of oxides. Python helps us to test the patterns.