Science of Electricity

Electron Flow-Atomic Structure All matter is made of small particles called Atoms Atoms are formed by varying numbers of neutrons, protons and electrons. Neutrons and protons are found in the interior of the atom called the nucleus Electrons orbit at various levels based on the number of electrons. Each level is called an Electron Orbit. Electrons in the outermost orbit are called valence electrons The Periodic Table of the Elements display materials and the number of their protons, neutrons and electrons

Electricity-Movement of Electrons If there are 1,2 or 3 electrons in the atoms outer orbit they are called free electrons and can move easily from one atom to another This flow of electrons is from one atom to another along a pathway is called Electricity deo/10065/Electricity-and- Magnetism-Atoms-and- Electrons deo/10065/Electricity-and- Magnetism-Atoms-and- Electrons

Conductors An element that conducts electricity allows electrons to flow easily through it. The key to determining if an element will conduct electricity is in the outer most shell of electrons or valence. An element is a conductor if its outer layer contains 3 or fewer electrons Most conductors are metals A metal is a good conductor of heat and electricity Conductors are located in the lower left of the periodic table Copper has one valence electron in its outer orbital. This one valence electron makes copper and excellent conductor of electricity

Semiconductors An element that is neither a good conductor nor a good insulator. It allows some current to flow, yet has a considerable amount of resistance. Yet semiconductors are important industrial materials for use in electronic devices such as, transistors, integrated circuits and solar cells. The key to determining if an element is a semiconductor is in the outer most shell of electrons or valence. An element is a semiconductor if its outer layer contains exactly 4 electrons. Example: Silicon

Insulators An element that does not allow electrons to move around freely within it. Insulators resist the flow of electrons. Most materials that are nonmetals are good insulators. Insulators are located in the upper right of the periodic table Common insulators include wood, plastic and rubber Electric cords are surrounded by rubber, plastic and sometimes cloth

Sources of Electricity The flow of electrons can be found in nature in the form of static electricity-a collection of non motile electrons. The electrons begin to flow or discharge when contact is made between 2 conductors. Lightning is a form of static electricity Ex. The discharge of static electricity can result when you walk across a carpeted floor and then reach out for a metal door knob. Valence electrons jump from your hand to the door knob causing a spark. Electrons flow from the negatively charged cloud to the ground. Thunder is the sound of molecule collisions

Sources of Electricity-Batteries Chemical reactions can also be used to create a flow of electrons Batteries produce electricity through chemical reactions Conversion of chemical energy to electricity takes place in a voltaic cell. A voltaic cell has a (-) charged cathode, a (+) charged anode and a liquid called an electrolyte through which the electrons flow. The flow of electrons will occur when the pathway for electron flow outside of the voltaic cell is completed Household batteries are single voltaic cells

Activity 2.1-Electricity (100pts) Pick a partner Complete the hand out on electricity together. Make sure all questions are answered and you both have put your names and the date on the front page Be sure your handout is turned in Extra Credit-25 pts. Create 5 questions with the answers to quiz another team Exchange your questions with another team