Lewis Dot Diagrams & Ions

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Lewis Dot Diagrams& IonsS2-2-01 Relate an element’s position on the periodic table to its combiningcapacity (valence).

Lewis dot diagrams In grade 9, you learned how to represent the atom by using Bohr Diagrams.Since Bohr diagrams can be a bit cumbersome to draw, we can use a shorter,more convenient notation.Lewis Dot Diagrams (Electron Dot Diagrams) A Lewis dot diagram is a way to represent an element and its VALENCEelectrons. In a Lewis dot diagram, DOTS or other small symbols are placed around theCHEMICAL SYMBOL of an element to represent the valence electrons. Electrons are either PAIRED or UNPAIRED. The first 4 ELECTRONS will alwaysbe UNPAIRED (except Helium, which has two dots that are paired). THE NEXT 4 ELECTRONS WILL PAIR UP WITH THE FIRST 4 DOTS. All elements in the same group/family will have SIMILAR Lewis dot diagramsEXCEPT He.

Lewis dot diagrams Examples:Draw Bohr AND Lewis Dot diagrams for the following elements.ElementHeliumPotassiumBohr DiagramLewis DotGroup #

Lewis dot diagrams Examples:Draw Bohr AND Lewis Dot diagrams for the following elements.ElementCarbonPhosphorusBohr DiagramLewis DotGroup #

Lewis dot diagrams In the table below, Write the name of each family above its column and drawthe Lewis dot diagram for the first 18 elements of the periodic table.Questions?1. Why might elements of the same group/family have similar properties?

Lewis dot diagrams Questions?2. Which family is likely to want to:a) Lose 1 electron?b) Gain 2 electrons?3.Choose 2 elements that you think may be likely to “combine”. Give a reasonfor your answer.4.What do you think determines the “combining capacity” (how elementscombine) of an element?

Charged Atoms Why is it so dangerous to use electricity around water? Tap water is not PURE! It contains CHARGED ATOMS that move inthe solution and can carry ELECTRIC CURRENT.We call these charged atoms IONS. An atom gets a charge by having aDIFFERENT amount of ELECTRONS than PROTONS.Since PROTONS are STUCK in the nucleus, atoms can only gain or loseELECTRONS to FILL the OUTER SHELL and get a charge.

Negative Ions If an atom GAINS ELECTRONS, it becomes MORE NEGATIVE, and is aNEGATIVE ion.Ex) Draw a bohr diagram for the following, and determine the ion thatthey would likely form:1. Oxygen2. Fluorine

Positive Ions If an atom LOSES ELECTRONS, it becomes LESS NEGATIVE, and is aPOSITIVE ion.Ex) Draw a bohr diagram for the following, and determine the ion thatthey would likely form:1. Lithium2. Beryllium

Examples Determine the charge on each of the following, and write the symbol for rogen

Try these ones 1. What is the ionic charge if Calcium loses its valence electrons?Write the ion using the chemical symbol with the charge properly.2. a) How would sulphur “fill” its outer electron shell?b) What would be the charge of the resulting ion?c) Write the correct symbol and charge for the sulphur ion.

Things we need to consider Do you notice what types of elements lose electrons and which onesgain electrons? Why don’t atoms gain/lose protons? What would result if they did? What would happen if they gained or lost neutrons?

Lewis dot diagrams In grade 9, you learned how to represent the atom by using Bohr Diagrams. Since Bohr diagrams can be a bit cumbersome to draw, we can use a shorter, more convenient notation. Lewis Dot Diagrams (Electron Dot Diagrams) A Lewis dot diagram is a way to represent an element and its VALENCE electrons.