Electron Theory Introduction Structure and Matter Atoms and Molecules Atomic Structure Electron Flow

Introduction

In this section we will discuss the concept of Matter. Structure and Matter

Matter Definition: Anything that occupies space and has mass. Structure and Matter

Matter  Can be solid, liquid or gas Ice Water Air

Structure and Matter Matter  Can be solid, liquid or gas  Can be element, compound, or mixture

Structure and Matter Matter  Can be solid, liquid or gas  Can be element, compound, or mixture Element- Is the basic building block of nature  Purest form of matter. Can not be divided into simpler substances (see periodic table)  Hydrogen  Oxygen  Carbon

Structure and Matter Matter  Can be solid, liquid or gas  Can be element, compound, or mixture Element- Is the basic building block of nature Compound- Two or more chemically combined elements  Contain the same proportion throughout  CO 2 H2OH2O

Structure and Matter Matter  Can be solid, liquid or gas  Can be element, compound, or mixture Element- Is the basic building block of nature Compound- Two or more chemically combined elements Mixture- Two or more elements not chemically combined, (proportion may vary).  i.e. Saltwater, Sand and Gravel

Atoms and Molecules Atom Molecule Molecular Compound Ionic Compound

Atoms and Molecules Atom- Smallest part of an element that retains the properties of that element  Electrons  Neutrons  Protons Electrons Nucleus contains Protons & neutrons

Atoms and Molecules Atom  Electrons Negative charge (-)  Neutrons  Protons Electrons Nucleus contains Protons & neutrons

Atoms and Molecules Atom  Electrons  Neutrons Neutral charge within the nucleus  Protons Electrons Nucleus contains Protons & neutrons

Atoms and Molecules Atom  Electrons  Neutrons  Protons Positive charge Within nucleus Electrons Nucleus contains Protons & neutrons

Atoms Have a Nucleus  Protons (positive charge)  Neutrons (neutral charge) Orbiting electrons (negative charge)

Bohr Model (Hydrogen) Electron Nucleus (1 proton 1 neutron) H N=1

Bohr Model (Helium) Electron Nucleus (2 protons 2 neutrons) He N=1 Electron

Bohr Model (Lithium) 1 valence electron Nucleus (3 protons 4 neutrons) Li N=1 N=2

Bohr Model The number of electrons in each shell is determined by the formula: #electrons=2n 2

Bohr Model (Copper) 1 valence electron Nucleus (29 protons 35 neutrons) Cu N=1 N=2 N=3 N=4 N=1=2(1) 2 =2 N=2=2(2) 2 =8 N=3=2(3) 2 =18 N=4=2(4) 2 =32 60

Copper Element Cu Copper

Copper Element Name Cu Copper

Copper Element Atomic Number Name Cu Copper

Copper Element Atomic Number Name Cu Copper Chemical Symbol

Copper Element Atomic Number Name Cu Copper Chemical Symbol Atomic Weight

Electrons charge The charge of 1 electron = 1.602x Coulombs Or 1 Coulomb = 6.24x10 18 electrons

Electrons excitation Electrons will stay in orbit as long as the bond is present between the electron and the protons Cu

Electrons excitation When energy is present enough to break the proton and electron’s bond, the electron will release from the atoms outer most (valence) shell. Cu Light, Heat, or EMF

Electrons excitation Direction of electron flow is produced when positive forces are strong enough to pull electrons in a direction. Cu + -

Electrons excitation Recall 1 Coulomb = 6.24x10 18 electrons That’s a heck of a lot of electrons!!!! 6,240,000,000,000,000,000 to be exact!!!!

Electrons Flow Current = The directional flow of electrons from a negative to positive

Electrons Flow 1 Amp = the amount of 1 coulomb of electrons (6.24x10 18 ) crossing an area per second 6.24x10 18 electrons/second _ +

Electrons Flow This is defined as Current Flow “I” through a conductor 6.24x10 18 electrons/second _ +

Electrons Flow If we were to say that 2 Amps is flowing in the conductor the # of electrons is (6.24x10 18 ) x 2 and so on… x10 18 electrons/second _ +

Electrons Flow In an ideal world, current flow (electron movement) through a conductor would not have any resistance. 6.24x10 18 electrons/second _ +

Electrons Flow As we shall see later, this is not the case. 6.24x10 18 electrons/second _ +

Electrons Flow Until then simply understand current flow is the movement of electrons through a conductive material 6.24x10 18 electrons/second _ +

Practice Problem: If a copper wire has 50mA of current flowing through it, how many electrons are passing through a single cross-sectional area each second?

Practice Problem: If a copper wire has 50mA of current flowing through it, how many electrons are passing through a single cross-sectional area each second? Solution: (6.24x10 18 )x.05 = 3.17x10 17 electrons/second

End of Presentation