EONS LEARNING

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    • Resources >
      • Study Skills
      • Periodic Table
      • Common Ion Sheet
      • The Scientific Method
      • Doing Background Research
    • Introduction and Course Philosophy
    • Unit 1: Beginning Chemistry >
      • Lesson 1: The Atom >
        • What is an Atom?
        • The Structure of Atoms
        • The Periodic Table
        • Modeling Atoms
      • Lesson 2: Chemical Bonding >
        • Why Do Atoms Form Bonds?
        • Ionic Bonding
        • Covalent Bonding
        • Intermolecular Attraction
      • Lesson 3: Chemical Nomenclature >
        • Octet Rule
        • Ionic Compounds
        • Covalent Molecules
      • Lesson 4: Molecular Molecules >
        • Modeling Ionic Compounds
        • Modeling Covalent Molecules
      • Lesson 5: States of Matter >
        • States of Matter
        • Phase Changes
      • Lesson 6: Density >
        • What is Density?
        • Calculating Density
      • Lesson 7: Thermodynamics >
        • Temperature
        • Heat
        • Gas Laws
      • Lesson 8: Solution Chemistry >
        • Diffusion
        • Solutions and Molarity
        • Semi-Permeable Membranes
      • Lesson 9: Thermal Expansion >
        • Thermal Expansion
    • Unit 2: Earth Science >
      • Lesson 10: Earth at a Glance >
        • Perspective
        • Maps
      • Lesson 11: Layers of the Earth >
        • Layers of the Earth
      • Lesson 12: Plate Tectonics >
        • Plate Tectonics
      • Lesson 13: Rocks and Minerals >
        • Rocks and Minerals
      • Lesson 14: Particle Sorting >
        • Differentiation
        • Deposition of Sediment
      • Lesson 15: The Atmosphere >
        • Composition of the Atmosphere
        • Layers of the Atmosphere
        • Change Over Time
        • Atmospheric Disruption
    • Unit 3: The Cell >
      • Lesson 16: Life >
        • What is Life?
        • Structural Hierarchy of Living Things
      • Lesson 17: Biochemistry >
        • Intro to Biochemistry
        • Water
        • Micromolecules
        • Energy, Carbohydrates, Lipids
        • Protein and Nucleic Acid
      • Lesson 18: Cells >
        • What are Cells?
        • Microscopy
        • Plant and Animal Cells
      • Lesson 19: Membrane Transport >
        • A Special Environment
        • The Structure of Membranes
        • Membrane Transport
      • Lesson 20: Energy and Cell Respiration >
        • Energy in Biology
        • Energy Diagrams
        • Glycolysis and Anaerobic Respiration
        • Aerobic Cellular Respiration
      • Lesson 21: Photosynthesis >
        • Plants Get Energy From The Sun
        • Photosynthesis Process
        • Energy, Ecosystems, and the Environment
    • Unit 4: Anatomy and Physiology >
      • Lesson 22: The Human Body >
        • What Are Bodies Made Of?
        • What Do Bodies Do?
      • Lesson 23: The Nervous System >
        • The Nervous System
        • Neuronal Communication
        • The Central Nervous System
      • Lesson 24: The Endocrine System >
        • The Endocrine System
        • Hormones
        • Hormones, Puberty, and Reproduction
      • Lesson 25: The Integumentary System >
        • The Integumentary System
      • Lesson 26: The Musculoskeletal System >
        • The Skeletal System
        • The Muscular System
        • Anatomy Of The Musculoskeletal System
      • Lesson 27: The Cardiovascular System >
        • Blood and Blood Vessels
        • The Heart
      • Lesson 28: The Respiratory System >
        • The Respiratory System
      • Lesson 29: The Digestive System >
        • The Digestive System
        • Nutrition
      • Lesson 30: The Excretory System >
        • The Excretory System
      • Lesson 31: The Immune System >
        • Disease and Infection
        • Immunity
    • Units 5-6 Coming Soon
  • Workbench
    • Unit 1 >
      • EIS >
        • Lesson 1: Atoms
        • Lesson 2: Chemical Bonding
        • Lesson 3: Chemical Nomenclature
        • Lesson 4: Molecular Models
        • Lesson 5: States of Matter
        • Lesson 6: Density
        • Lesson 7: Thermodynamics
        • Lesson 8: Solution Chemistry
        • Lesson 9: Thermal Expansion
      • Unit 1: Project
      • Unit 1: Exam Review
      • Unit 1: Exam
    • Unit 2 >
      • EIS >
        • Lesson 10: Earth at a Glance
        • Lesson 11: Layers of the Earth
        • Lesson 12: Plate Tectonics
        • Lesson 13: Rocks and Minerals
        • Lesson 14: Particle Sorting
        • Lesson 15: The Atmosphere
      • Unit 2: Project
      • Unit 2: Exam Review
      • Unit 2: Exam
    • Unit 3 >
      • EIS >
        • Lesson 16: Life
        • Lesson 17: Biochemsitry
        • Lesson 18: Cells
        • Lesson 19: Membrane Transport
        • Lesson 20: Energy and Cell Respiration
        • Lesson 21: Photosynthesis
      • Unit 3: Project
      • Unit 3: Exam Review
      • Unit 3: Exam
    • Unit 4 >
      • EIS >
        • 22: The Human Body
        • 23: The Nervous System
        • 24: The Endocrine System
        • 25: The Integumentary System
        • 26: The Musculoskeletal System
        • 27: The Cardiovascular System
        • 28: The Respiratory System
        • 29: The Digestive System
        • 30: The Excretory System
        • 31: The Immune System
      • Unit 4 Project
      • Unit 4 Exam Review
      • Unit 4 Exam
    • Units 5-6 Coming Soon
  • Donate
  • Home
  • About Us
  • Classroom
    • Resources >
      • Study Skills
      • Periodic Table
      • Common Ion Sheet
      • The Scientific Method
      • Doing Background Research
    • Introduction and Course Philosophy
    • Unit 1: Beginning Chemistry >
      • Lesson 1: The Atom >
        • What is an Atom?
        • The Structure of Atoms
        • The Periodic Table
        • Modeling Atoms
      • Lesson 2: Chemical Bonding >
        • Why Do Atoms Form Bonds?
        • Ionic Bonding
        • Covalent Bonding
        • Intermolecular Attraction
      • Lesson 3: Chemical Nomenclature >
        • Octet Rule
        • Ionic Compounds
        • Covalent Molecules
      • Lesson 4: Molecular Molecules >
        • Modeling Ionic Compounds
        • Modeling Covalent Molecules
      • Lesson 5: States of Matter >
        • States of Matter
        • Phase Changes
      • Lesson 6: Density >
        • What is Density?
        • Calculating Density
      • Lesson 7: Thermodynamics >
        • Temperature
        • Heat
        • Gas Laws
      • Lesson 8: Solution Chemistry >
        • Diffusion
        • Solutions and Molarity
        • Semi-Permeable Membranes
      • Lesson 9: Thermal Expansion >
        • Thermal Expansion
    • Unit 2: Earth Science >
      • Lesson 10: Earth at a Glance >
        • Perspective
        • Maps
      • Lesson 11: Layers of the Earth >
        • Layers of the Earth
      • Lesson 12: Plate Tectonics >
        • Plate Tectonics
      • Lesson 13: Rocks and Minerals >
        • Rocks and Minerals
      • Lesson 14: Particle Sorting >
        • Differentiation
        • Deposition of Sediment
      • Lesson 15: The Atmosphere >
        • Composition of the Atmosphere
        • Layers of the Atmosphere
        • Change Over Time
        • Atmospheric Disruption
    • Unit 3: The Cell >
      • Lesson 16: Life >
        • What is Life?
        • Structural Hierarchy of Living Things
      • Lesson 17: Biochemistry >
        • Intro to Biochemistry
        • Water
        • Micromolecules
        • Energy, Carbohydrates, Lipids
        • Protein and Nucleic Acid
      • Lesson 18: Cells >
        • What are Cells?
        • Microscopy
        • Plant and Animal Cells
      • Lesson 19: Membrane Transport >
        • A Special Environment
        • The Structure of Membranes
        • Membrane Transport
      • Lesson 20: Energy and Cell Respiration >
        • Energy in Biology
        • Energy Diagrams
        • Glycolysis and Anaerobic Respiration
        • Aerobic Cellular Respiration
      • Lesson 21: Photosynthesis >
        • Plants Get Energy From The Sun
        • Photosynthesis Process
        • Energy, Ecosystems, and the Environment
    • Unit 4: Anatomy and Physiology >
      • Lesson 22: The Human Body >
        • What Are Bodies Made Of?
        • What Do Bodies Do?
      • Lesson 23: The Nervous System >
        • The Nervous System
        • Neuronal Communication
        • The Central Nervous System
      • Lesson 24: The Endocrine System >
        • The Endocrine System
        • Hormones
        • Hormones, Puberty, and Reproduction
      • Lesson 25: The Integumentary System >
        • The Integumentary System
      • Lesson 26: The Musculoskeletal System >
        • The Skeletal System
        • The Muscular System
        • Anatomy Of The Musculoskeletal System
      • Lesson 27: The Cardiovascular System >
        • Blood and Blood Vessels
        • The Heart
      • Lesson 28: The Respiratory System >
        • The Respiratory System
      • Lesson 29: The Digestive System >
        • The Digestive System
        • Nutrition
      • Lesson 30: The Excretory System >
        • The Excretory System
      • Lesson 31: The Immune System >
        • Disease and Infection
        • Immunity
    • Units 5-6 Coming Soon
  • Workbench
    • Unit 1 >
      • EIS >
        • Lesson 1: Atoms
        • Lesson 2: Chemical Bonding
        • Lesson 3: Chemical Nomenclature
        • Lesson 4: Molecular Models
        • Lesson 5: States of Matter
        • Lesson 6: Density
        • Lesson 7: Thermodynamics
        • Lesson 8: Solution Chemistry
        • Lesson 9: Thermal Expansion
      • Unit 1: Project
      • Unit 1: Exam Review
      • Unit 1: Exam
    • Unit 2 >
      • EIS >
        • Lesson 10: Earth at a Glance
        • Lesson 11: Layers of the Earth
        • Lesson 12: Plate Tectonics
        • Lesson 13: Rocks and Minerals
        • Lesson 14: Particle Sorting
        • Lesson 15: The Atmosphere
      • Unit 2: Project
      • Unit 2: Exam Review
      • Unit 2: Exam
    • Unit 3 >
      • EIS >
        • Lesson 16: Life
        • Lesson 17: Biochemsitry
        • Lesson 18: Cells
        • Lesson 19: Membrane Transport
        • Lesson 20: Energy and Cell Respiration
        • Lesson 21: Photosynthesis
      • Unit 3: Project
      • Unit 3: Exam Review
      • Unit 3: Exam
    • Unit 4 >
      • EIS >
        • 22: The Human Body
        • 23: The Nervous System
        • 24: The Endocrine System
        • 25: The Integumentary System
        • 26: The Musculoskeletal System
        • 27: The Cardiovascular System
        • 28: The Respiratory System
        • 29: The Digestive System
        • 30: The Excretory System
        • 31: The Immune System
      • Unit 4 Project
      • Unit 4 Exam Review
      • Unit 4 Exam
    • Units 5-6 Coming Soon
  • Donate

Modeling Ionic Compounds

We've already discussed what types of atoms will attract each other. We've also talked a little bit about why atoms come together--because of electrostatics and stability. However, we still don’t know exactly how the atoms actually combine to form molecules: Or, in other words, what compounds and molecules look like. You can think of atoms as kind of like LEGOs that adhere to form compounds, molecules, and everything that surrounds us. (This, of course, is over-simplified and inaccurate. But, it’s useful enough for our level).

Way back when we made atomic symbols and Bohr Models, we learned that scientists like to use pictures to show people things instead of trying to explain it to them. Remember this guy?

Picture
This is the "car" we might come up with if we had never seen a car and someone just told us that it has an engine and a place for people to sit, described a steering wheel, and explained how it gets you places faster than walking would. So, to avoid confusion, we make pictures. This lesson is basically a scientific art class with atoms.

Modeling Ionic Compounds

As you've learned, there are two main types of chemical bonding: ionic bonding and covalent bonding. You should know that an ionic bond is between a metal and a nonmetal, and should understand that it involves charged ions. It involves a nonmetal, which basically steals an electron (or two or three) from a metal. This makes the nonmetal negatively charged and the metal positively charged. Since opposites attract, they stick together in an ionic bond. But, these are words, and scientists like pictures. So let's learn to draw pictures!

The Octet Rule / I Wanna Be A Noble Gas

Remember when I told you the octet rule was super important? Well, it's about to become even more important. So, if you don't remember it, go back and review before continuing this lesson.

Brief reminder: 🎵I wanna be a noble gas, like neon and helium… 🎵(Side note: do people still watch Pokemon?)

Lewis Dot Structures

There are several ways to show atoms forming molecules, including with Bohr models like we’ve done in the past. As you may have noticed, it’s a little cumbersome to draw the entire Bohr model for an atom every time we want to draw a structure, especially when we’re only really interested in the valence electrons. For this reason, the most common way to draw molecular models is with the Lewis dot structure.

As it happens, Lewis dot structures were invented by a guy named Lewis (how convenient that he managed to invent something with the same name as him!). They’re extremely simple to read: each dot represents a valence electron, and each atom is denoted with its atomic symbol. To draw them, start with the atomic symbol in the middle, and just keep putting dots in a clockwise circle until there are enough for one atom. To figure out how many are enough, just count the boxes on the Periodic table like we did with Bohr models. It looks a little something like this:

Picture
Modeling ionic compounds

Modeling Ionic Compounds with Lewis Dot Structures

Modeling an ionic compound (and the chemical reaction that makes it) with Lewis dot structures is almost as easy as drawing a Lewis dot structure. It's just 4 easy steps:
​
Picture
Modeling an ionic reaction with Lewis dot structures
  1. Write out the relevant ions with their charges and decide how many of each ion is required to make a balanced equation. Remember, all charges should add up to zero. One easy way to do this is to say that the charges of one ion should be the subscript on the other (simplified to the lowest common denominator). So, Al³⁺ and Cl⁻ would make AlCl₃, and Al³⁺ and O²⁻ would make Al₂O₃. We sometimes call this the criss-cross rule. 
  2. Draw Lewis Dot Structures for each atom in the molecule. If there is more than one instance of each atom, make sure to draw all of them!
  3. Transfer electrons from atom to atom (arrows). Make sure each gets 8 electrons. (Or 2, for H, Li, and Be.)
  4. Draw the new Lewis dot structures. Be sure to indicate the charge of the atom. With larger structures like these, we do this by putting the structure in brackets and putting the charge outside the brackets, as shown in the picture. You can show electrostatic attraction between the newly formed ions with a dotted line.
Picture
Using the criss-cross rule
Drawing Lewis dot structures and modeling ionic compounds isn't too complicated, but it is important to know these steps in order to understand our next step: modeling covalent compounds. As always, the more you practice, the easier it gets.

Summary

You should know:
  • How to draw Lewis dot structures for single atoms/ions, by figuring out the number of valence electrons.
  • How to model ionic compounds using Lewis dot structures, by showing how valence electrons get transferred and how the resulting charged ions are held together by electrostatic interactions.

​Learning Activity

Learning Activity Modeling Ionic Compounds.pdf
File Size: 50 kb
File Type: pdf
Download File

This is one of those things that you’ll never really learn unless you do it—so, this activity will give you the chance to do it!

For the following, you may draw out your answers in any format you like, but it is probably easiest to do them on a piece of paper. 

For the following atoms or ions, please draw the correct Lewis dot structure.


  1. Magnesium
  2. Bromine (note: Ignore the transition metals. This should look very similar to chlorine.)
  3. Bromide (note: Ignore the transition metals. This should look very similar to chloride.)
  4. Carbon 
  5. Silicon
  6. Phosphorus
  7. Neon
  8. Nitrogen
  9. Oxygen
  10. Hydrogen

Model the following ionic compounds and the reaction that produced them. Outline all 4 steps as shown in the lesson.

  1. Calcium fluoride
  2. Lithium oxide
Picture
Next: Modeling covalent molecules

Content contributors: Eli Levine, Nancy Jiang, Emma Moulton
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