Presentation on theme: "Introduction to Chemistry Bohr Models and Lewis Dot Structures"— Presentation transcript:
1 Introduction to Chemistry Bohr Models and Lewis Dot Structures
2 AtomsBasic unit of matterConsists of: Electrons, Protons, & Neutrons
3 Atoms Review Consists of: Electrons, Protons, & Neutrons Electrons: particles orbiting around nucleus with a negative chargeProtons: particles in the nucleus with positive chargeNeutrons: particles in the nucleus with no charge
4 Element a pure chemical substance consisting of one type of atom Atomic Number= Number of Protons or ElectronsSymbolNameAtomic Mass= Number of Protons + Number of Neutrons
5 Periodic Table of Elements VIII+1IIIIIIVVVIVII+2+3+/-4-3-2-1= element charges= Valence Electrons
6 Periods and GroupsPeriods go from left to rightGroups go up and down
7 Bohr Models Proposed by Niels Bohr in 1915 Electrons orbit the nucleus in orbits that have a set size and energy.The energy of the orbit is related to its size.The lowest energy is found in the smallest orbit.
8 Energy LevelsWhen two atoms approach each other their nucleus do not touchOnly electrons are involved in Chemical Reactions
9 Bohr Diagrams Find out which period (row) your element is in. Elements in the 1st period have one energy level.Elements in the 2nd period have two energy levels, and so on.
10 Bohr Models RULE Show just electrons with energy levels 1st level holds 22nd holds 83rd holds 18 but is stable at 82-8-8 RULE!!Must fill an energy level to capacity before moving to the next energy level
11 Bohr Diagrams Try the following elements on your own: H He O Al Ne K P:N:
12 Valence ElectronsElectrons that are found on the outer most energy level. This determines the elements chemical properties
13 Lewis Dot Structures Named after Gilbert Newton Lewis Show the bonding between atoms of a molecule, and the lone pairs of electrons that may exist in the moleculeShow only valence electrons (outer energy level)
14 Lewis Dot Structures and Groups Find out which group (columns) your element is in.Elements in the 1st group have one valence electron.Elements in the 2nd group have two valence electrons, and so on.
15 Lewis DotTry the following elements on your own:HHeOAlNeK