Lessons 25 and 26

Lesson 25:

This lesson summarized the four ways that atoms can bond together. They are as follows: metallic, ionic, molecular covalent, and network covalent. Elements fall into these categories based on their conductive and soluble properties. Other identifying factors include the elements themselves: are they nonmetals, metals, or both? Usually, metals conduct electricity while nonmetals do not, and if the two are stuck together and dissolved, the compound is soluble and sometimes still conductive.

Problems:
1.) What does insoluble mean? Insoluble simply means that a compound or substance cannot be dissolved in water or any other liquid.

3.) What generalization can you make about a substance that is soluble in water and can conduct electricity when dissolved? Explain your reasoning. This substance is most likely an ionic compound. If it conducts electricity when dissolved, that means it contains a metal, and typically ionic compounds can be dissolved because they have a nonmetal element in them.

Lesson 26:

Lesson 25 hinted vaguely at what 26 would be about; we learned exactly what the four categories that elements fall into are called. Metallic, ionic, molecular covalent, and network covalent are used to describe how the electrons in atoms keep compounds "glued" together. Metallic bonds usually describe single, metal elements. An example of this would be a solid gold ring. It conducts, but does not dissolve, and is made SOLELY of metal atoms. Ionic bonds describe metals and nonmetals bonded together. They dissolve, conduct, and conduct when dissolved. Molecular covalent compounds can sometimes dissolve, as some are liquids and some are gases, but they do not conduct electricity. Typically, we see molecular covalence in compounds made completely of nonmetals. Finally, network covalent compounds neither dissolve nor conduct electricity. The electrons in network covalent compounds are so tightly stuck together, almost in a lattice-like pattern, that the substances resulting from them are very hard to break apart. Diamond is a great example, being one of the hardest rocks on Earth.

Problems:
3.) Determine the type of bonding in each substance:
A.) zinc, Zn - Metallic bond, single element.
B.) propane, C3H8(l) - Molecular covalent, liquid nonmetal compound
C.) calcium carbonate, CaCO3(s) - Ionic bond, solid metal and nonmetal compound

7.) Suppose you have a mixture of sodium chloride, NaCl, and carbon, C. Explain how you can use water to separate the two substances. NaCl in itself is an ionic compound that is soluble in water. The sodium and chlorine completely break apart, allowing the sodium to conduct electricity through the water. The chlorine, being a nonmetal, doesn't do much, and if you added carbon to the compound, you'd have atoms of sodium, chlorine, and carbon floating around in water. To separate them would be quite easy.