Lewis Dot Structures and Ionic Bonds

Ionic Compounds
1. Lewis Dot Symbols
2. The octet Rule
3. Ionic Bond Model
4. Signs and Magnitude
5. Lewis Structures

Lewis Dot and Groups

Groups Identify the number of valence electrons.

• Dots represent the number of valence electrons in an atom.

Multiple Choice

Using this picture, which group do these atoms belong to?

• Group 2

• Group 12

• Group 8

Multiple Choice

Which structure belongs to group 14 or 4A?

Octet Rule

Stable atoms (except H & He) require eight valence electrons.

• Atoms that have less than eight tend to react to attain an octet and become more stable.

• This is true for both ionic and covalent bonds.

Multiple Choice

How do atoms meet the octet rule?

• They lose or gain electrons in the outer most level

• They lose of gain electrons from the inner most level

Multiple Choice

According to the octet rule, atoms of elements react with each other in order to attain ____ electrons in their outermost energy level or shell.

• 4

• 6

• 8

Ionic Bond Model

Formed by two or more charged atoms

• ​A monatomic bond is formed between a cation and an anion.

  • a metal and a nonmetal

• A polyatomic bond is formed between more than one atom.

  • Metal and nonmetals

Common Polyatomics

These are located on your Periodic Table handout.

Multiple Choice

Carbonate

• CO₃^-2

• CO₃^-3

• CO₂^-2

Signs and Magnitude

Overall, the molecule has no net (total) charge

• Cations and Anions must be in the lowest ratios that result in the formation of an uncharged molecule.

  • Crisscross method with charges

Signs and Magnitude

• ​A monoatomic bond is formed between a cation and an anion.

  • a metal and a nonmetal

• A polyatomic bond is formed between more than one atom.

  • Metal and nonmetals

Multiple Choice

What is the correct chemical formula for Na (sodium) and O (oxygen) forming the ionic compound Sodium Oxide?

• NaO

• NaO₂

• Na₂O

Signs and Magnitude

Polyatomic molecules

• The crisscross method requires parentheses or brackets to distinguish between the polyatomic atoms and the quantity of the anion or cation.

Multiple Choice

Which of the following is the correct ionic formula for a Barium and Phosphate compound?

• Ba₃(PO₄)

• Ba₃(PO₄)₂

• Ba₂(PO₄)₃

​Cations and anions are depicted in brackets, with the valence electrons inside the brackets and the charge above and to the right.

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Dot structures of ionic compounds

​When the ratio of cation to anion is not 1:1, coefficients are used to show the relative numbers of ions.​

Dot structures of ionic compounds