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Lewis Dot Diagrams and Ions

Lewis Dot Diagrams and Ions. Valence Electrons. The valence electrons are the electrons in the outermost shell of the atom Consider sodium: How many protons? How many neutrons? How many electrons? Draw a Bohr model for sodium. Valence Electrons. Bohr model for sodium:

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Lewis Dot Diagrams and Ions

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  1. Lewis Dot Diagrams and Ions

  2. Valence Electrons • The valence electrons are the electrons in the outermost shell of the atom • Consider sodium: • How many protons? • How many neutrons? • How many electrons? • Draw a Bohr model for sodium

  3. Valence Electrons • Bohr model for sodium: • The electron(s) in the highest shell are valence electrons

  4. Lewis Dot Diagram • To draw a Lewis Dot Diagram: • Write the element symbol • Figure out how many valence electrons the atom has • Use dots to represent the valence electrons • Put them in pairs around the 4 sides of the element symbol • For example – try sodium

  5. Lewis Structure Practice • Draw a Lewis Structure for: Calcium Neon Silicon

  6. Ions • Ions are atoms that have the same number of protons, but different numbers of electrons • An ion forms when an atom gains or loses electrons to become more stable • Which group is the most stable? • How many valence electrons does that group have?

  7. Ions • When nonmetals form ions, they tend to gain electrons to fill their valence shell with 8 electrons • When metals form ions, they tend to lose all of their valence electrons

  8. Positive Ion Formation • Atoms in Group 1 lose 1 electron to form ions with a +1 charge • Atoms in Group 2 lose 2 electrons to form ions with a +2 charge • Atoms in Group 13 lose 3 electrons to form ions with a +3 charge • Positive ions are called cations

  9. Negative Ion Formation • Atoms in Group 17 gain 1 electron to form ions with a -1 charge • Atoms in Group 16 gain 2 electrons to form ions with a -2 charge • Atoms in Group 15 gain 3 electrons to form ions with a -3 charge • Negative ions are called anions

  10. Ionic Compounds • When atoms form ionic compounds, an atom transfers one or more of its valence electrons to another atom. • Consider NaCl • Na loses 1 electron to become Na+1 • Cl gains 1 electron to become Cl-1 • The transfer of electrons from one atom to the other causes a more stable arrangement of electrons.

  11. Ionic Compounds • May be made from a metal and a nonmetal - KI • May be made from a metal and a polyatomic ion (Look at your reference table) – LiOH • May be made from two polyatomic ions - NH4C2H3O2

  12. Naming Ionic Compounds • The name of the positive ion stays the same • The end of the element name of the negative ion is changed to an –ide suffix • Chlorine to chloride • Sulfur to sulfide • Phosphorus to phosphide • Polyatomic ions stay as they are written

  13. Ionic Formulas • What ion does sodium form? • Na+1 • What ion does chlorine form? • Cl-1 • What do we change the name of the negative ion to? • Chloride • What is the name of the compound?

  14. Ionic Formulas • What is the formula for the compound made from sodium and chloride ions? • What is the compound made from potassium and iodide ions?

  15. Ionic Formulas Activity • Work in pairs to complete the activity. • Please put all of the shapes back in the bags when you are finished.

  16. Rules for Naming Ionic Compounds • The first element keeps its name. • For monatomic ions, the second element gets the –ide suffix (ending). • Polyatomic ions always keep their names whether they are first or second.

  17. Practice • Name the following ionic compounds: KF MgBr2 Li2S Ca3N2 NaNO3 Mg(OH)2

  18. Exit Ticket • Draw a Lewis Structure for magnesium • Give the charge on a magnesium ion • Give the formula for a compound made from magnesium and bromine • Give the name for CaCl2

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