ABSTRACT
For the purpose of this book, and generally to discuss concepts of
chemistry and biology, it is sufficient to look at atoms as consisting
of protons, neutrons and electrons.22 An atom’smass is concentrated
in the nucleus, made of protons and neutrons. Protons carry a positive charge, neutrons don’t carry any charge, but electrons
are negatively charged. There are about ninety naturally occurring
different arrangements of protons, neutrons and electrons and they
are called the elements. All elements are electrically neutral, their nucleic (proton) charges are balanced by electronic charges. An
element’s atomic number is therefore equal to the number of its
protons/electrons.
