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Forming Ions

Forming Ions. Why do Ions form?. All elements want to be like their closest noble gas and have 8 electrons in their last energy level Some elements have to lose electrons while others gain electrons to get this “stable state”. Positively Charged Ions ( Cat ions ).

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Forming Ions

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  1. Forming Ions

  2. Why do Ions form? • All elements want to be like their closest noble gas and have 8 electrons in their last energy level • Some elements have to lose electrons while others gain electrons to get this “stable state”

  3. Positively Charged Ions (Cations) • When an atom loses an electron, you get a POSITIVELY charged ion • Cations are usually metals (less than 4 electrons in their outer shell) • Examples: Na+, Mg 2+, Al 3+

  4. Negatively Charged Ions (Anions) • When an atom gains an electron, you get a NEGATIVELY charged ion. • Anions are usually non-metals ( 4 or more than 4 electrons in their outer shell) • Examples: O2-, F-, N3-

  5. Calculating Charge (copy into notes) • Each proton has a charge of +1, each electron has a charge of -1 • Sulfur has 16 electrons (6 valence electrons) • To reach a stable state, it wants 8 valence electrons • It gains TWO electrons, it now has 18e- (8 valence e) • Therefore, these have a charge of -18 (18 x -1) • It also has 16 p+ • therefore, these have a charge of +16 (16 x +1) • Total Charge = -18 + (+16) = -2

  6. Drawing an Ion Bohr Rutherford Diagram • Determine the charge and how many electrons are gained or lost • Draw a Bohr Rutherford diagram • Make sure to draw the diagram with electrons gained or electrons lost to form an ion • Put a big square bracket around the diagram • Write the ion charge on the top right of the square brackets

  7. Practice by drawing a Ion Bohr Rutherford Diagram for Sulfur • Check your answer on the next slide

  8. Describing an Ion • Sulfur has a charge of -2, therefore we write: Ion Notation: S-2 Ion Bohr Rutherford Diagram: -2 16p+ 16n0

  9. Chemical Bond • An attraction between two or more elements that allow the formation of a new substance • Only the valence electrons are involved in creating a chemical bond

  10. Forming Ionic Compounds • Videos – Dogs and ions

  11. Ionic Bonds • Between a metal and a non-metal • Electrons are transferred from the metal to the non-metal • From the video, why are the metal and non-metal attracted?

  12. Creating an Ionic Formula • Determine the charge on the metal and the non-metal • Write them on the top right of each substance (the metal should always be written first) • Use the cross-over method to create the chemical formula • If there is a common multiple, divide each subscript by the common multiple to simplify

  13. Example • Pick a metal and a non-metal

  14. Naming an Ionic Compound • Write the name of the metal • Write the name of the non-metal only replace the ending with ‘ide’ • Oxygen becomes Oxide • Sulphur becomes Sulphide

  15. Practice!

  16. Multivalent Ions • A multivalent ion can have several charges • Look at the back of your periodic table • Most of these are transition metals • Iron has 2 possible charges - +2, +3 • Which one should we use? • We use roman numerals to let people know which one was used. Ex: Iron (II) Oxide or Iron (III) Oxide

  17. To determine which charge • Reverse Criss Cross Cu Br2 Cu Br2 Cu2 Br1 Since the charge on Bromine is -1, the charge on copper must be +2 Therefore, Copper (II) Bromide

  18. Polyatomic Ions • Polyatomic ions are chemical best friends that are bonded together and go looking for electrons • We treat each polyatomic ion, the same way we would treat a regular ion • Still use criss cross method but they have their own special names (see back of periodic table)

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