Main Group Ions

Chapter 7: Chemical Formulas & Chemical Compounds

Chapter 7 Section 1: Chemical Names and Formulas

​Introduction

• ​There are millions of natural and synthetic compounds in the world

  • ​Many compounds have both common names and scientific names

    • ​Calcium Carbonate: Limestone

    • ​Sodium Chloride: Table Salt

    • ​Dihydrogen monoxide: Water

  • ​Common Names can vary from region to region, and don't reveal much about the compound itself

​Significance of a chemical formula

• ​A chemical formula tells the relative number of each atom in a chemical compound

  • ​Molecular Compounds: the formula shows how many of each atom are in one molecule

    • ​Octane: C₈H₈ has 8 carbon and 8 hydrogen

  • ​Ionic compounds: The formula shows the simplest ratio of a compound's cations and anions

    • ​Alumiunium Sulfate: Al₂(SO₄)₃ has 2 aluminium ions and three sulfate ions

      • ​Each sulfate has 1 Sulfur and four Oxygen

​Monoatomic Ions

• ​Many main group elements can form ions by either losing or gaining electrons

  • ​Allows them to get a Noble gas Configuration

    • ​Group 1 lose 1 electron to gain a +1 Charge

    • ​Group 2 loses 2 electrons for a +2 Charge

    • ​Group 15 Gains 3 electrons for a -3 Charge

    • Group 16 Gains three electrons for a -2 Charge

• ​Monoatomic ions: Ions formed from a single atom

  • ​Many main group elements and some d-block elements do this, but some exceptions

​Naming Monoatomic ions

• ​Cations are called by their element name+cation

  • ​K⁺ = Potassium cation

  • ​Mg²⁺ = Magnesium Cation

• ​Anions change the ending of the element's name to end in -ide

  • ​F^- = Fluoride

  • ​N^3- = Nitride

​Binary Ionic Compounds

• ​Binary Compounds: Compounds Consisting Solely of two elements

  • ​Total number of Positive Charges and negative charges must be equal

    • ​Example: Magnesium bromide

      • ​Magnesium is a group 2 metal and forms a +2 Cation

      • ​Bromine is a -1 anion

      • ​In order to balance the two out, you need 2 bromine for each magnesium

        • ​Mg²⁺ + Br₂ -> MgBr₂

          • ​Charges are not included in the final product

​Binary Ionic Compounds

• ​Another method of Balancing: Crossing over

  • ​Write the Symbols side by side, cation first

  • ​cross over the charges using the absolute value of each atoms charge

  • ​Check the subscripts to make sure you have the smallest ratio possible

​Quick Practice

​Work with a partner to Complete Page 223 # 1-2.

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​You have 5 minutes. Turn in at the end of class