- Developing and Using Models
- Analyzing and Interpreting Data
- Engaging in Argument from Evidence
- Constructing Explanations and Designing Solutions
- Using Mathematics and Computational Thinking
- Obtaining, Evaluating, and Communicating Information
- Planning and carrying out Investigations.
Objectives
By the end of this unit, students should be able to
- Distinguish between the locations of metal atoms versus non-metal atoms on the periodic table.
- Use electronegativity values to predict whether an ionic or covalent bond is most likely to form.
- Identify compounds as ionic, covalent, or metallic based on their chemical formula.
- Predict the number of atoms needed in a molecular formula.
- Examine ratios of atoms in compounds.
- List some properties of ionic, covalent, and metallic bonds.
- Compare and contrast the basic structure of ionic and molecular compounds.
- Determine the number of valence electrons for an atom.
- Create a Lewis dot structure for an atom, covalent compound, and ionic compound.
- Predict the charge of an ion.
- Predict the molecular shape of a covalent molecule based upon its Lewis dot structure.
- Explain why stable, neutral ionic compounds are formed from cations and anions.
- Explain why different quantities of ions combine to make different compounds.
- Explain the purposes of superscripts and subscripts in chemical formulas.
- Name and write the formulas for binary and ternary ionic compounds.
- Visualize “free-moving electrons” in metallic bonding.
- Identify that different metals have different properties.
- Conceptualize the impact of one electron pair domain acting upon another, and understand how those interactions result in the molecular geometries predicted by VSEPR theory.
- Describe the implications of electron pair repulsions on molecular shape.
- Understand that the molecular shape names are descriptions of the actual shape.
- Make the correlation between geometry, nonbonding pairs and molecular shape.
- Relate the shape of a molecule and the relative electronegativity values of its constituent atoms to the polarity of the molecule.
- Explain the meaning of the following: cohesion, adhesion, surface tension, and capillary action.
- Describe the unique behaviors of water molecules, and why they are important.
- Determine the polarity of molecules.
- Rank molecules in order of increasing strength of van der Waals forces, given a set of structural formulas for several compounds.
- Manipulate models to demonstrate molecular orientations giving rise to London dispersion forces, dipole-dipole forces and hydrogen bonds.
- Identify the intermolecular forces present in chemical substances.
- Recognize that physical properties are related to intermolecular forces.
Chemistry Topics
This unit supports students’ understanding of
- Ionic Bonding
- Covalent Bonding
- Naming Compounds
- Molecular Formulas
- Molecular Structure
- Lewis Dot Structures
- Molecular Shapes
- VSEPR Theory
- Molecular Geometry
- Electronegativity
- Polarity
- Physical Properties
- Metallic Bonds
- Magnetism
- Electric current
- Electrons
- Resonance
- Properties of Water
- Intermolecular Forces
- London Dispersion Forces
- Dipole-dipole Forces
- Hydrogen Bonding
Time
Teacher Preparation: See individual resources.
Lesson: 8-12 class periods, depending on class level.
Materials
- Refer to the materials list given with each individual activity.
Safety
- Refer to the safety instructions given with each individual activity.
Teacher Notes
- The activities shown below are listed in the order that they should be completed.
- The number of activities you use will depend upon the level of students you are teaching.
- The teacher notes, student handouts, and additional materials can be accessed on the page for each individual activity.
- Please note that most of these resources are AACT member benefits.
Classroom Resources:
Bonding Basics
- Help students visualize how different chemical bonds form by using the Bonding Animation to introduce the concept of bonding. Examples of ionic, covalent, and polar covalent bonds are animated, and students are given a set of compounds to predict the bonding types.
- Use the Ionic & Covalent Bonding Simulation from the September 2016 issue of ChemistrySolutions to allow students to investigate ionic and covalent bonding. Students interact with different combinations of atoms and are tasked with determining the type of bond and the number of atoms needed to form each. The simulation visually differentiates between the transferring of electrons when forming an ionic compound and the sharing of electrons when forming a covalent compound. Students also become familiar with the molecular formula and geometric shape, as well as the naming system for each type of bond. This simulation is unlocked and can be used by your students. It also includes a teacher guide and student activity sheet .
Covalent, Ionic & Metallic Bonding and Properties
- Students construct ionic compounds by balancing the charges on cations and ions in the activity, Constructing Ionic Compounds. This activity shows students how to form stable ionic compounds, explain why different number of cations and ions are needed to form those compounds, and use superscripts and subscripts in chemical formulas. Another option is the Ionic Bonding Puzzle which provides puzzle pieces that students use to create neutral ionic compounds. Once they have made a neutral ionic compound they can use electron dot diagrams to show the formation of the compounds. Finally they will name the ionic compounds.
- Students build models of ionic and covalent compounds with the Lego Modeling of Compounds lab. By the end of this lab, they will be able to build molecular models, examine the ratio of atoms in compounds, and compare the basic structure of ionic and covalent substances.
- Use one of our ionic bonding “bracket” activities to help students demonstrate their understanding of ionic bonding and ionic properties.
- The activity, My Name is Bond, Ionic Bond begins with pairs of students playing a game of “Ionic Compound War” to build eight compounds. Then then transfer the compounds to a “bracket” and use their knowledge of ionic bonding, along with a solubility chart, to predict the strongest and weakest bond between four pairs of ionic substances.
- With a similar “brackets” resource, Ionic Bonding Brackets, students apply their knowledge of ionic bond strength and its relationship to melting point and solubility. After analyzing the ionic charge and radius to predict the strongest and weakest bond between four pairs of ionic substances, they will then determine which will be the least soluble.
Lewis Structures, Molecular Geometry (VSEPR) and Polarity
- The Molecular Compound lesson teaches students how to name molecular compounds and create Lewis Dot Structures using a single dice and element cards. This resource includes a set of element cards for your students to use as they work through the activity.
- Introduce molecular geometry with the VSEPR Modeling activity, which has students construct physical models of molecules and then derive the arrangement of the atoms. This guided inquiry activity allows them to conceptualize the impact of one electron pair domain acting upon another. They will also understand how those interactions result in the molecular geometries predicted by VSEPR theory. Find out more about this VSEPR Modeling Activity in a related article from the September 2017 issue of Chemistry Solutions.
- An alternate option is the activity, VSEPR with Balloons, which allows students to explore Valence Shell Electron Pair Repulsion Theory using balloon models. Since balloons tend to take up as much space as they can when tied together, they can look like models of central atoms in VSEPR theory, making a great metaphor for the model. This activity is an extension of Shapes of Molecules found on the AACT website.
- Students can further explore Valence Shell Electron Pair Repulsion Theory using the activity, VSEPR with Balloons. Balloons tend to take up as much space as they can when tied together, so they look like models of central atoms in VSEPR theory, making a great metaphor for the model. This resource is an extension of the Shapes of Molecules activity.
Intermolecular Forces (IMFs)
- Introduce the relationship between molecular structure and properties with the lesson, The Chemistry of Water Video. Students watch a video that is part of the American Chemical Society video series Chemistry Basics and answer questions as it plays. This activity will help them learn about how the shape of a molecule will determine properties such as melting and boiling point.
- Students investigate intermolecular attractive forces in a lesson plan, The Great Race: A Study of van der Waals Forces by constructing molecules and determining the forces of attraction between them: London dispersion, dipole-dipole, and hydrogen bonding. Given a set of structural formulas, they then rank the molecules in order of increasing strength of van der Waals forces.
- The Intermolecular Forces & Physical Properties demonstration allows students to observe and compare the properties of surface tension, beading, evaporation, and miscibility for water and acetone. This resource includes alignment with both the AP Chemistry Curriculum Framework and NGSS.
- If you’d prefer a lab activity, use the Physical Properties lab to lead them through an investigation of how intermolecular forces affect physical properties. This lab will help them understand what happens in the freezing and melting process and how solubility works.
- If your students are tactile learners, use one or both of these resources to help them model covalent bonding and polarity with the use of string and Styrofoam balls.
- In the activity, Modeling Bond Polarity, students model the pull of electrons in a bond between two elements, demonstrating covalent bonding. In particular differentiating between polar and nonpolar bonds.
- In a similar activity, Modeling Molecular Polarity, students use electronegativity values and their knowledge of covalent bonding to model the bonds in a molecule. They then use that information to help them determine the overall polarity of a molecule.
- Another option is the Intermolecular Forces simulation, which allows students to review the three major types of intermolecular forces – London dispersion forces, dipole-dipole interactions, and hydrogen bonding – through short video clips and accompanying text. They then answer quiz questions using the relative strengths of these forces to compare different substances given their name, formula, and Lewis structure, and put them in order based on the strength of their intermolecular forces, their boiling point, or their vapor pressure. The simulation is designed as a five question quiz for students to use multiple times.
Extension Activities
Connect chemistry with current events with one or both of the following activities:
- The Chemistry of Hand Sanitizer and Soap lab also shows students connections between chemistry and current events. They model the interaction between hand sanitizer particles and virus particles, as well as between soap particles and virus particles. They then apply their understanding of molecular structure and intermolecular forces to analyze their observations and behavior of the particles.
- In addition to connecting chemistry with current events, give your students extra unit conversion practice with the activity, Designing an Effective Respiratory Cloth Mask. Students use unit conversion to help compare sizes of molecules, viruses, and droplets and then use them to interpret graphical data. They then use their findings to design a cloth mask that helps protect its wearer against infection by SARS-CoV-2, the coronavirus that causes COVID-19.
Culminating Projects
Do you like to end your unit with a culminating activity? We have two projects in our Molecules & Bonding resource library.
- Using Molecular Modeling, students research a molecule selected from a teacher approved list, construct a three-dimensional model of the molecule, and present their research to the class in a 7-10 minute oral presentation.
- If you do not have the time for students to complete a long-term project, use Properties of Common Molecular Substance instead of the Molecular Modeling project. This resource allows students to apply their knowledge of molecular polarity, shape, and intermolecular forces to explain the differences in properties between different covalent substances.
