Topic 8 Bohr Models and Lewis dot Diagrams

Topic #8: Bohr Models and Lewis dot Diagrams EQ: How do Bohr models and Lewis dot diagrams help us illustrate an atom’s structure?

What do we know? Atoms have 2 main parts Electron cloud -- contains electrons Nucleus – contains protons and neutrons Electrons = e. Protons = p+ Neutrons = n 0 l

What do you need to know? There are 7 possible orbitals l You can determine how many orbitals your model has by looking at what period (row) the element is on l The orbitals hold a specific number of electrons (which is the same as the atomic number) l

How many electrons per orbital? Period 1 orbital (ring) 1: 2 e. Period 2 orbital (ring) 1: 2 eorbital (ring) 2: 8 e. Period 3 orbital (ring) 1: 2 eorbital (ring) 2: 8 eorbital (ring) 3: 8 e. Period 4 orbital (ring) 1: 2 eorbital (ring) 2: 8 eorbital (ring) 3: 18 eorbital (ring) 4: 8 e-

Information to create a Bohr model l l l Element name and symbol: Magnesium (Mg) Atomic number: 12 Mass number: 24 Protons: 12 Electrons: 12 Neutrons: (24 - 12) = 12

Bohr model for Mg 12 p+ 12 n

Bohr model for Al 13 p+ 14 n 0

Valence Electrons Valence electrons are electrons on the last energy level. l How many Valence electrons does aluminum have? l

Lewis Dot Diagrams Lewis dot diagrams are simple to draw: l Step one: Write symbol from the periodic table. l Step Two: Add the correct number of valence electrons around the symbol. (preferred fill pattern) 3 6 l Al 7 4 X 85 2 1

Draw the following Bohr models and Lewis dot diagrams on your blank sheet of paper at the beginning of the topic. Boron Carbon Nitrogen Oxygen Fluorine Aluminum Silicon Phosphorus Sulfur Chlorine