Ions and Ionic Bonding

Electrons and Energy Levels First, let’s review: First, let’s review: Electrons are found in energy levels Electrons are found in energy levels Energy levelCapacity Level # 12 electrons Level # 28 electrons Level # 38 electrons

Draw models of: Lithium Magnesium Fluorine

Lewis Dot Diagrams Remember dot diagrams only show valence electrons. o Valence electrons are they only ones that participate in bonding/chemical reactions Draw the Dot diagrams for the elements you just drew out. (Li, Mg, F)

Ions & Ionic Compounds Opposites attract

Formation of ions Remember Atomic structure: What is true about the NUMBER of protons and electrons in an atom? Ions are charged particles (the protons (+) and electrons (-) are not equal) Ions form when electrons are lost or gained from an atom

Types of ions Cations Have a POSITIVE (+) charge Form from METALS Electrons are LOST Anions Have a NEGATIVE (-) charge Form from NON- METALS Electrons are GAINED

Ions You need your periodic tables Valance electrons - electrons in the outer most energy level. Octet rule - 8 valance electrons is STABLE like the Noble Gases Except Helium – only 2 electrons (1 st energy lvl) 8 is great ! Atoms want to ionize to form an Octet

Oxidation numbers – Ion charges Use your PERIODIC TABLE! Identify the number of valence electrons This is related to the oxidation number or “charge” on the ion once it forms. Remember: eight is great! (8 = gr8!) All elements want to be like noble gases “pseudo noble gas configuration”

Examples of ionization Sodium = Na (one valance electron) Chlorine = Cl (7 valance electrons) Sodium ion = Na +1 ( Loses one electron to form an octet) Chloride ion = Cl -1 (gains one electron to form an Octet)

Try fluorine and sodium

Additional examples Magnesium = Mg (two valance electrons) Oxygen = O (six valance electrons) Magnesium ion = Mg +2 (loses two electrons to form an octet) Oxide ion = O -2 (gains two electrons to form an octet)

Use Electron dot diagrams to show what happens when Magnesium bonds with Oxygen (use the last slide to help)

Now try bonding Na and O together…

A word about Subscript H 2 O – What is it? What does the “2” indicate? When writing out chemical COMPOUNDS: use the chemical symbol and SUBSCRIPT this indicates how many of each ion (atom) is in the compound

Summary of ionic compounds 1. Electrically neutral 2. Formed from Cation(s) & Anion(s) 3. Metal ion with a nonmetal ion 4. The net charge of the compound is zero 5. 8 IS GREAT For pages 36-39

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