Chemistry
Chapter 8: 1-3
Homework
Valence Electrons
Chapter 8: 1-3 Homework
- Reading Preparation
- WebLecture
- Study Activity
- Preparation work for chat
- Online Quiz
- Lab Instructions
Reading Preparation
Textbook assignment: Read Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 8: Sections 1-3.
Study Notes
- 8.1: We identify two kinds of bonds in chemistry, ionic bonds and covalent bonds, as the extreme ends of a range of sharing types. Covalent bonds form when the force of attractive for electrons from each atom in the bond is about the same. Ionic bonds form when attractive forces are so uneven that one atom "steals" one or more electrons from the second atom in the bond.
- 8.2: We need to distinguish between those electrons in an atom's electron configuration that participate in bonds and those that don't. The s and p electrons in the outermost energy level will always participate and are called valence electrons. The electrons in the d orbitals of transition elements participate in bonds and determine the chemical properties of the metal involved. Electrons on inner orbitals, or core electrons do not participate in bond formation.
We can diagram the electrons for each element to identify the number of valence electrons available for bonding. Lewis structures are used to show how bonds form when electrons are shared between atoms of similar electronegativity, with most atoms forming stable orbital configurations when they share enough electrons to have 8 in their valence shell (an octet of 2 s and 6 p electrons). Oxoacids will donate one hydrogen ion (H+) without changing their electron configuration. Molecules with the same number of electrons and the same Lewis structures are isoelectronic and share similar chemical reaction properties. - 8.3: Formal charge is the charge on a polyatomic molecule or ion, calculated from the group number of the atom, the number of lone pairs, and the number of bonding electrons of the atom. Lone pairs belong to one atom; bonded pairs are divided between the bonding atoms. Do not confuse formal charge (which tells us something about a stable molecule) with oxidation numbers (which predict how electrons will move as elements recombine during oxidation-reduction reactions).
Important Formulae
| Concept | Equation | Notes |
|---|---|---|
| Formal Charge | NVE - [LPE + 1/2(BE)] |
NVE: number of valence electrons in the uncombined atom
LPE: numer of lone pair electrons in the atom BE: number of bonding electrons around atom |
Web Lecture
Read the following weblecture before chat: Chemical Bonding and Ionic Bonds
Study Activity
Videos for Chapter 8: Chemical Bonds and Molecular Geometry
Review the Videos at Thinkwell Video Lessons.
- Under "Chemical Bonding: Fundamental Concepts: Valence Electrons and Chemical Bonding"
- Valence Electrons and Chemical Bonding
- Ionic Bonds
- Under "Chemical Bonding: Lewis Dot Structures"
- Lewis Dot Structures for Covalent Bonds
- Predicting Lewis Dot Structures
- Under "Chemical Bonding: Fundamental Concepts: Resonance Structures and Formal Charge"
- Formal Charge
Use the WISC-Online Lewis Dot Structures of Covalent Compounds. Use the "next" button to advance through the presentations and checkpoints. Be sure to answer the questions on valence electrons and apply the Lewis dot structure rules to the examples at the end of the exercise.
Chat Preparation Activities
- Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
- Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.
Chapter Quiz
- There is no chapter quiz YET.
Lab Work
LAB #6 GUIDED INQUIRY: Using qualitative methods to differentiate covalent and ionic bonds. -- Phase I
How are these atoms bonded together?
Using the resources below to explore your options, design an experiment to observe solid compounds and predict bond types for components, then identify appropriate qualitative and quantitative tests, building on techniques developed in Lab #4, and use these to collect any further data needed to deduce the type of bonding in a sample of a solid. You will need to interpret your data terms of the relative strength of interactions among and between the components. List your equipment and materials, and outline your process and the data you will collect.
References
- APGIE Investigation 6: Bonding in Solids: What’s in that Bottle?
- IGHCE Lab 19.3-4 Qualitative Analysis of Inorganic Cations and Anions
- Alternative Lab: Molecular Geometry
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