Electrical Principles Chapter 1 Matter, Atoms, Conductors, Insulators, SemiConductors, Elements, Molecules, Compounds, and Electron Flow Matter Matter What is Matter? Matter is anything that has mass and occupies space. Matter can exist in a state of gas, liquid, or solid. Matter A Solid is a state of matter that has a definite shape and volume. A Liquid is a state of matter that a definite volume but not a definite shape. A Gas is a state of matter that is fluid, has a relatively low density, and is highly compressible. Matter All Matter has electrical properties. Electrical Behavior of matter varies according to the physical makeup of the matter. Some Matter allows electricity to flow through it more easily. This type of Matter is called a Conductor. Examples: Copper Matter A Conductor is a material that has very little resistance and allows electricity to flow easily through it. Material that does not allow electricity to flow easily is called an Insulator. An Insulator is a material that has very high resistance and restricts the flow of electricity. Example: Glass, Rubber, Plastic, Paper Questions!?!?!?!?! Atoms Atoms The word Atom is a Greek word meaning a particle that is too small to subdivide. Neils Bohr, A Danish Physicist, Put forward a theory in 1913 about the atom and the subatomic particles that make up the atom. This model is still in use today. Bohr’s atomic structure model combines the ideas of Planck, Rutherford, and Einstein. Atoms An Atom is the smallest particle that an element can be reduced to and still maintain the properties of that element. Three principal parts of the Atom are: Electron Neutron Proton Atoms An Electron is a negatively charged particle in an Atom. A Neutron is a neutral particle, with a mass approximately the same as a proton, that exists in the nucleus of an Atom. A Proton is a particle with a positive electrical charge of 1 Unit that exists in the nucleus of the Atom. Atoms Atoms The electrons orbit the nucleus of an atom. The neutron and proton combine to form the nucleus. The Atomic Number of an Atom describes the number of protons that exist within the nucleus. Atoms The number of neutrons within an atom’s nucleus can be calculated by subtracting the atomic number (protons) from the atomic weight (combined protons and neutrons). Atoms Example – Beryllium has an Atomic Number of 4 (Protons) and an Atomic Weight of 9 (Protons and Neutrons). Subtracting the beryllium atoms weight (9) from the Atomic Number (4), we can determine the number of neutrons to be 5. Atoms A Neutral Atom or Balanced Atom is an atom that has an equal number of protons and orbiting electrons, so the net positive proton charge is equal but opposite to the net negative electron charge, resulting in a balanced or neutral state. Atoms Orbiting electrons travel around the nucleus at varying distances from the nucleus and these orbital paths are known as shells or bands. The orbital shell nearest the nucleus is referred to as the first or K shell. The second is known as the L shell, the third is M, the fourth is N, the fifth is O, the sixth is P, and the seventh is the Q shell. The outer most electron occupied shell is known as the Valence Shell or Ring and electrons in this shell are termed Valence Electrons. Atoms Atoms Laws of Attraction and Repulsion or Law of Charges Like charges repel one another. (Like Charges are positive and positive or negative and negative). Unlike Charges attract one another. (Unlike Charges are positive and negative or negative and positive). Atoms Laws of Attraction and Repulsion or Law of Charges Positively charged particles attracts a negatively charged particle Positively charged particles repels against another positively charged particle. Negatively charged particles repel another negatively charged particle. Atoms Laws of Attraction and Repulsion or Law of Charges Atoms Laws of Attraction and Repulsion or Law of Charges Orbiting negative electrons are attracted toward the positive nucleus. Orbiting electrons remain in a stable orbit due to two equal but opposite forces. The centrifugal outward force exerted on the electrons due to the orbit counteracts the attractive force trying to pull the electrons toward the nucleus due to the unlike charges. Atoms Laws of Attraction and Repulsion or Law of Charges Due to the distance from the nucleus, valence electrons are described as being loosely bound to the atom. These electrons can easily be dislodged from their outer orbital shell by any external force, to become a Free Electron. Atoms Laws of Attraction and Repulsion or Law of Charges The gaining or losing of electrons produces and electric charge in the atom. All charges particles exert forces on one another, even if they are not in physical contact. The exerted force is due to the electric field that surrounds all charged particles. Valence Electrons A Valence Shell is the outermost shell of an atom and contains the electrons that form new compounds. Example – two hydrogen atoms combine with the electrons in the outer shell of an oxygen atom to form water (H2O). The electrons in the Valence Shell are important because they can be used to produce an electric current flow. The number of electrons in the Valence Shell determines whether the material is a Conductor, SemiConductor, or Insulator. Questions!?!?!?!?! Conductors, Insulators and SemiConductors Conductors, Insulators and SemiConductors A Conductor is a material that has very little resistance and allows electricity to flow easily through it. Conductors have three or less valence electrons. Electricity is flowing through the electrons of the outer most Valence Shell into the electrons of the adjoining atom’s Valence Shell outer most electrons. Conductors, Insulators and SemiConductors Material that does not allow electricity to flow easily is called an Insulator. An Insulator is a material that has very high resistance and restricts the flow of electricity. Example: Glass, Rubber, Plastic, Paper Insulators have five or more valence electrons. Conductors, Insulators and SemiConductors A SemiConductor is an electronic device that has electrical conductivity between that of a conductor (high conductivity) and that of an insulator (low conductivity). SemiConductors, such as carbon, germanium, and silicon, are made from materials that have exactly four valence electrons. SemiConductor materials do not conduct electricity easily and are not good insulators. Questions!?!?!?!?! Elements, Molecules and Compounds Elements, Molecules and Compounds An atom is the smallest unit of a natural element, or an element is a substance consisting of a large number of the same atom. Combinations of elements are known as Compounds and the smallest unit of a compound is called a Molecule. Water is an example of a liquid compound in which the Molecule (H2O) is a combination of an explosive gas (hydrogen) and a very vital gas (oxygen). Elements, Molecules and Compounds Elements are the basic materials that make up all matter. An Element is a substance that can not be chemically broken down and contains atoms of only one variety. All solids, liquids, and gases are made up of Elements. Some matter may be made up of only one Element, but most matter is made up of more than one Element. There are 109 Elements, 92 of which are natural. Millions of Compounds can be made by combining different Elements. Elements, Molecules and Compounds When elements are combined, the properties of the compound may differ considerably from that of the individual elements. Electrical properties of compounds are important in water treatment, gas and oil refining, food processing, chemical and pharmaceutical manufacturing, medical applications, and research. Low voltage electricity is passed through the compounds and used to take measurements that provide information about the product being tested. Electron Flow Electron Flow Two theories – Conventional Current Flow and Electron Current Flow. Conventional Current – current flows from positive to negative. Conventional Current Flow is used in electrical field and by electrical engineers to aid in explanation electrical circuit properties. Electron Flow Electron Current Flow – current flows from negative to positive. Electron Current Flow is used in electronic semiconductor field to assist in explaining the operation of solid-state electronic components. Questions!?!?!?!?!