C1.1 The Fundamental Ideas in Chemistry

Atoms

The Nucleus of the atom contains protons and neutrons. It is positively charged, very dense, very small, nearly all of the mass of the atom is concentrated in the nucleus.
The Electron Cloud virtually has no mass. It is deformable and it is negatively charged and contains electrons.

The relative electrical charge for a proton is +1, neutron is 0 and electron is -1. In a neutral atom, the number of electrons is equal to the number of protons in the nucleus. Therefore atoms have no overall electrical charge ie overall neutral.

The number of protons in an atom of an element is its atomic number.
The sum of the protons and neutrons in an atom is its mass number.

Electrons occupy particular energy levels. You can use the term energy level or shell for where an electron is.

You should be able to represent the electronic structure of the first 20 elements of the periodic table in the following forms e.g sodium 2,8,1

Periodic Table

All substances are made of atoms and a substance made up of one type of atom is called an element. There are about 100 different elements and these elements are shown in the periodic table…