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Catalyst: 10.27.2008. Find the atomic #, mass #, # protons, # electrons, and # neutrons for the following elements: Beryllium & Lithium. Objective. Explain how electrons are placed in the electron cloud. Identify valence electrons Make atomic diagrams with proper electrons
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Catalyst: 10.27.2008 Find the atomic #, mass #, # protons, # electrons, and # neutrons for the following elements:Beryllium & Lithium
Objective Explain how electrons are placed in the electron cloud. Identify valence electrons Make atomic diagrams with proper electrons Construct Lewis Dot Diagrams to show valence electrons
Electron Location Where are electrons located in an atom? Outer electron cloud What do they do there? Constantly moving How are they arranged in the electron cloud? In a specific pattern called energy shells (or levels)
Energy Shells Each shell or level has a specific amount of energy (E) Each shell can only hold a certain amount of electrons.
Energy Shells Each energy shell/level is represented by a circle around the nucleus of the atom. The first (lowest) energy level holds only 2 electrons After this level is filled up,electrons go to a higher (outer) E level. Electrons fill the lower levels andthen move to higher (outer) levels.
Energy Shells No matter how many energy levels there are, the outermost energy level can only hold at most 8 electrons The outermost energy level is called the valence shell.
Energy Shell Example (Left page) Carbon: What is its symbol? What is the atomic number? What is the atomic mass? How many protons does it have? How many electrons does it have? How many neutrons does it have? How many electrons go in the first shell? How many electrons go in the next shell? How many valence electrons are there?
Energy Shell Example (Left page) Carbon: What is its symbol? C What is the atomic number? 6 What is the atomic mass? 12 How many protons does it have? How many electrons does it have? How many neutrons does it have? How many electrons go in the first shell? How many electrons go in the next shell? How many valence electrons are there?
Energy Shell Example (Left page) Carbon: What is its symbol? C What is the atomic number? 6 What is the atomic mass? 12 How many protons does it have? 6 How many electrons does it have? 6 How many neutrons does it have? How many electrons go in the first shell? How many electrons go in the next shell? How many valence electrons are there?
Energy Shell Example (Left page) Carbon: What is its symbol? C What is the atomic number? 6 What is the atomic mass? 12 How many protons does it have? 6 How many electrons does it have? 6 How many neutrons does it have? 6 How many electrons go in the first shell? 2 How many electrons go in the next shell? 4 How many valence electrons are there? 4
Energy Shell Example (Left page) Carbon: What is its symbol? C What is the atomic number? 6 What is the atomic mass? 12 How many protons does it have? 6 How many electrons does it have? 6 How many neutrons does it have? 6 How many electrons go in the first shell? 2 How many electrons go in the next shell? 4 How many valence electrons are there? 4
Energy Shell Example #2 (Left page) Draw an atomic diagram for Helium. How many valence electrons are there in Helium?
e- e- Energy Shell Example #2 (Left page) 2 p+2 n0 Draw an atomic diagram for Helium. How many valence electrons are there in Helium? 2e-
Lewis Dot Diagrams Lewis Dot Diagrams are a way to show you how many valence electrons are in an atom. How many valence electrons were in Carbon? 4 valence e- Lewis Dot Diagram of Carbon:
Lewis Dot Diagram Practice (Left Side) Draw the Lewis Dot Diagram for each of the following:1. Element X has 2 valence electrons.2. Element Y has 5 valence electrons.3. Element Z has 7 valence electrons.
e- e- Practice Problems 2 p+2 n0 You will create an atomic diagram with correct number of energy levels AND a Lewis Dot diagram for each of the of following elements: Boron, Nitrogen, Phosphorous, Chlorine, and Fluorine.
