Chemistry
Alcohol, sugar & co
The molecules in glucose and ethanol: carbon, hydrogen and a little oxygen.
What you need first
The sugar in your cocoa, the smell of ripe fruit, the glucose in a sports drink: these are all organic . They are built from just a few kinds of atoms, and yet nature makes an enormous variety from them. Here you learn to read their formulas and count the atoms inside.
More than just C and H
Pure like methane (CH₄) carry only carbon and hydrogen. If a formula also shows an O, it describes a completely different substance: not an odourless gas, but sweet sugar for example, or a liquid that mixes with water. So whether oxygen sits inside the molecule helps decide how a substance smells, tastes and behaves.
H₂O
The small ₂ counts the atom before it
Sugar as an energy store
Glucose has the formula C₆H₁₂O₆: six carbon, twelve hydrogen and six oxygen atoms. This molecule holds energy that your body can release. That is why glucose is an energy store: plants build it up in sunlight, and living things get the energy back out later.
Reading ethanol
Ethanol, the alcohol in disinfectant and methylated spirit, has the formula C₂H₆O. You read it like a blueprint: the small number after a letter tells how many atoms of that kind are present. If a number is missing, exactly one atom is meant. This way you can decode any formula atom by atom.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
How many hydrogen atoms does methane (CH₄) have?
Which kind of atom is in glucose and ethanol, but not in methane?
How many carbon atoms does glucose (C₆H₁₂O₆) have?
Match each formula to the organic substance it stands for.
How many oxygen atoms does ethanol (C₂H₆O) have?
If a formula has no small number after a letter, exactly … atom of that kind is meant.
Where this leads