Mixtures - AQA There are different ... structure - AQA Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The numbers of subatomic particles in an atom ...

An element with 17 protons will always be chlorine. However an element's mass numbers can vary, which means that it can have different numbers of neutrons. So although chlorine has a mass number ...

In fact, each gene in cellular DNA contains the code for a unique protein structure. Not only are these proteins assembled with different amino ... carbon atom linked to an amino group, a carboxyl ...