Atomic Structures © 2011 Project Lead The Way, Inc.Magic of Electrons

Atomic Structure Elements Atoms Components of an Atom Atomic Number Periodic Table of Elements Electrons Electron Orbits

Elements The simplest form of matter

Atoms The smallest piece of an element that contains all properties of that element

Components of an Atom Nucleus The center portion of an atom containing the protons and neutrons Protons Positively charged atomic particles Neutrons Uncharged atomic particles

Atomic Number The atomic number is equal to the number of protons in the nucleus of an atom. The atomic number identifies the element. How many protons are in this nucleus?

Periodic Table of Elements Which element has 4 protons? NASA

Electrons For this unit, we mainly care about electrons in atoms. Why? It is important to understand the “how and why” of the movement of electrons to understand electricity.

Electrons Negatively charged particles

Electrons The electrons reside in the electron cloud The clouds are divided into 7 energy levels Electrons “reside” in lowest energy levels whenever possible.

Electrons Areas within each energy level where electrons move around the nucleus of an atom are known as Electron Orbitals. There are four different type of orbitals, each type able to contain different numbers of electrons SharpDiffusePrincipalFundamental

What does all this have to do with Electricity? The number of electrons in the outer most level of an atom will determine if an element will allow electricity to flow. The ability of an atom to draw electrons to itself (away from its neighbors) is called Electronegativity.

Conductors and Insulators ConductorsInsulators Electrons flow easily between atoms 1-3 valence electrons in outer orbit Low Electronegativity Electron flow is difficult between atoms 5-8 valence electrons in outer orbit High Electronegativity

Conductors and Insulators Identify conductors and insulators Conductors Insulators

Metals, Non-Metals, & Metalloids

Combination of metal and non-metal properties Conduct heat & electricity better than insulators, but not as good as metals Solids Semi-conductors Poor Conductors Good Insulators Dull Luster Brittle Low Density Melt at lower temps High Electronegativity Good Conductors Poor Insulators Shiny Malleable High Density Low Electronegativity

Semiconductors Include Carbon, Germanium, and Silicon Contain 4 valence electrons Neither a good insulator, nor a good conductor, but can be made a better conductor through doping. Needed for transistors and microchips Silicon is most often used in electronic applications Silicon is an insulator at room temperature but becomes a conductor when heated

Electron Flow in Conductors An atom will lose a valence electron when “pushed” by an electron from another atom.

Electron Flow Electricity is created as electrons collide and transfer from atom to atom. Play Animation

Image Resources Microsoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from National Aeronautics and Space Administration (NASA). (n.d.). Genesis: Search for origins. Retrieved September 10, 2008, from html html