Chemistry問題(今日內,勁急,拜託)

Let assume there only 26 elements existed( actually lots more than that). Then from A to Z, each letter is an atom, you cannot break down A to a small letter but A can change to B, by radioactivity. A+B can be fused into other element. Now talking about molecule using the 26 letters one can make unlimited words. Like using A, C & T, you can form words such as "act" , "cat" , "tac" , "aact "& etc. So molecules are formed by atoms. They are quite different from the basic units atom. By using the basic building unit atom, nature forms small molecules involve only a few atoms, however there are giant molecules involves thousands of only a few atoms( by repeating atoms such as carbon, hydrogen, oxygen & others). Hope this can help.

Atom is a basic unit of matter
molecule is a group of atoms,which is sufficiently stable electrically neutral group.