Basic Electronics Engineering I : Structure of the Atom

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Basic Electronics Engineering I

:: Structure of the Atom

Structure of the Atom

An atom is the smallest particle of an element possessing the unique characteristics of that element. Atoms have a planetary type of structure. They consist of a central nucleus surrounded by orbiting electrons.

The nucleus consists of positively charged protons and uncharged particles called neutrons. An atom has the same number of electrons and protons. Thus the atom is electrically neutral

:: Valence Electrons

Copper Atom

Electrons orbit the nucleus at certain distances from the nucleus. Each orbit corresponds to a certain energy level. The electrons in the outermost orbit are called valence electrons. They have higher energy and are less tightly bound to the atom than those closer to the nucleus.

If a valence electron acquires a sufficient amount of energy, it can escape from the outer orbit. The escaped valence electron is called a free electron. It can migrate easily from one atom to another.

:: Kind of Materials

When electrons can move easily from atom to atom in a material, it is conductive. Metals are good conductors. They have a large amount of free electrons.

A material with a very few free electrons is an insulator. Insulators (dielectrics) cannot conduct electricity but can hold or store it.

Semiconductors conduct less than the conductors but more than the insulators. Because of their unique properties some of them are the basis for modern electronic devices such as diodes, transistors and integrated circuits.

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