Chemistry: CONCEPTS
There are so many different concepts used in studying chemistry. Some concepts like atoms, molecules, elements forms basis of chemistry.
As a cell is important in biology, the same importance is given to an atom in chemistry. An atom is the smallest particle that forms a matter. An atom can be further divided in to protons, neutrons and electrons.
The atomic number and the mass number are the consequences of protons, electrons and neutrons. The number of protons present in an atom is the atomic number of that element. Proton and electrons are [resent I equal among in any atom in an unexcited state. the protons carry a positive charge on them whereas an electron has a negative charge on it.
Mass number of an atom is the sum of number of protons + no of neutrons.
You can calculate any one out of neutrons, protons or electrons in an atom if you know the value of any two. The other concepts involve reactivity series of elements. Reactivity series is the arrangement of toms in terms of their reactivity. The elements that react powerfully are kept on the top of the reactivity series whereas the elements that are low in reactivity are listed below. All those elements that do not react at all are kept at the bottom of the reactivity series.
When two or more similar atoms combine with each other, they form elements and when these elements combine with other elements they form compounds.