ATOMIC+THEORY

__ ** INTRODUCTION ** __ Everything around us is made up of chemicals. Chemistry is a study of substances. The way they behave on their own and with each other. To understand how substances interact we need to know what they are made of. All of what we know about the structure of chemicals is based around observations of how they behave and interact. Early attempts to describe the basic building blocks of all things were inaccurate but still good theories for their time. The final model we have today of the atom is based on a number of theories which have developed over hundreds of years.

**ASSESSMENT - ATOMIC THEORY HISTORY** __** CURRENT ATOMIC THEORY **__ The present theory used for the structure of the atom is based upon that first proposed by Lord Rutherford in 1911. Rutherford proposed that all matter is made up of building blocks called ATOMS which cannot be broken down further. He suggested that atoms themselves consisted of a number of sub-atomic particles and the number and arrangement of these particles were what made up the range of atoms which everything is made up of. Atoms contain PROTONS (with a +ve electrical charge) and NEUTRONS (with no electrical charge) found in a central area called the NUCLEUS. They also contain ELECTRONS (with a –ve electrical charge) orbiting the nucleus. These particles are very small so most of the atom is empty space. At various times scientists find it useful to be able to visualise the structure of an atom of various elements with the particles shown. This is know as a Bohr diagram. The protons and neutrons are shown in the central nucleus and the electrons in their orbitals of shells. (Note: shell fill as follows (2,8,8,18,36) **ASSESSMENT - DRAWING ATOMS - BOHR DIAGRAMS.**