9: Attractive Forces
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All matter is subject to attractive forces, though we could ignore these when we talked about gases.
Sometimes these attractive forces are the ionic or covalent bonds that were explored previously, but these are not the only types of attractive forces. In this chapter we will introduce additional types of attractive forces. Some attractive forces are much weaker than those we’ve looked at previously. These are called intermolecular forces, and we will look at these in section 9.1. In section 9.2 we will look at some stronger bonds, both reviewing what we saw earlier and introducing some new possibilities.
Attractive forces are important to understand, because they are the reasons why matter will exist in condensed states such as solids and liquids. Attractive forces are also responsible for solutions forming (and for the substances that form when solutions are mixed together). In section 9.3 we will describe the phase transitions between different physical states. In section 9.4 we will discuss why solutions form based on attractive forces. And in section 9.5 we will revisit double replacement reactions with our new understanding of attractive forces.
Prior to starting chapter 9 you will want to make sure you are familiar with a few things introduced in previous chapters. The early sections of this chapter will assume you remember some of the concepts related to bonding and molecular polarity that were discussed previously. Section 9.5 builds on the concepts of predicting reactions that we last saw when first introducing chemical reactions. Please review these previous sections if necessary prior to starting this chapter.
- 9.1: Intermolecular Forces- Dispersion, Dipole–Dipole, Hydrogen Bonding
- All substances experience dispersion forces between their particles. Substances that are polar experience dipole-dipole interactions. Substances with covalent bonds between an H atom and N, O, or F atoms experience hydrogen bonding. The preferred phase of a substance depends on the strength of the intermolecular force and the energy of the particles.
- 9.2: Types of Crystalline Solids
- Crystalline substances can be described by the types of particles found within, and the types of chemical bonding that take place between the particles. There are four types of crystals: (1) ionic, (2) metallic, (3) covalent network, and (4) molecular.
- 9.3: Phase Transitions
- Phase changes can occur between any two phases of matter. All phase changes occur with a simultaneous change in energy. All phase changes are isothermal.
- 9.4: Solutions - Homogeneous Mixtures
- There are two types of mixtures: mixtures in which the substances are evenly mixed together (called a homogenous mixture, or solution) and a mixture in which the substances are not evenly mixed (called a heterogeneous mixture). When a solution, or homogenous mixture, is said to have uniform properties throughout, the definition is referring to properties at the particle level.
- 9.5: Precipitation Reactions
- A precipitation reaction is a reaction that yields an insoluble product—a precipitate—when two solutions are mixed. Thus precipitation reactions are a subclass of exchange reactions that occur between ionic compounds when one of the products is insoluble. Because both components of each compound change partners, such reactions are sometimes called double-displacement reactions.
- 9.E: Attractive Forces
- These are exercises and select solutions to company Chapter 10 of the "Beginning Chemistry" Textmap formulated around the Ball et al. textbook.