Learning Objectives:

• Name ionic and covalent compounds and derive their chemical formulas
• Observe absorption spectra of metal ions using flame test
• Draw Lewis structures of simple covalent compounds

In this laboratory exercise, we will learn how to derive formulas of ionic and covalent compounds and name them. We will also flame test for various metal ions and make models of simple covalent molecules.

• Read the lab before coming to class.  The expectation at Chamberlain (CCN/CU) is that you come to class fully prepared for lab.
• This lab will involve the use of acids and burners.  Be careful and mindful of your surroundings as you handle the chemicals and burners.
• Always check with your instructor regarding proper waste disposal
• Listen carefully  to the professor’s instructions and work safely
• Always follow the rules outlined in the safety contract
• If in doubt of how to use a piece of lab equipment, as you instructor.  Improper use of lab equipment can be dangerous or could damage lab materials.
• If you have any safety concerns, see your instructor.
• Always dress properly for lab.  Be sure to wear closed toed shoes and long pants to lab.  In lab, ware your safety equipment including goggles, lab coat, and gloves.
• Use deionized water (DI water) in your experiments.

Exploration 1: Explain the following terms (Complete prior to class).

• Cation
• Anion
• Ionic bond
• Polar covalent bond
• Nonpolar covalent bond
• Hydrogen bond

Exploration 2: Ionic compounds

Part 2A: Cations and their names

Metals form cations by donating electrons in their valence shell to satisfy the octet rule. The name of a cation is the same as name of the element. Complete Table 1 by providing names of cations, their chemical symbols and charges.

Part 2B: Anions and their Names

Non-metals form anions by accepting electrons to complete their valence shell and satisfy the octet rule. The name of an anion is never the same as the name of the element, but rather is named by adding the suffix –ide. Complete Table 2 by providing names of anions, their chemical symbols and charges.

Part 2C: Polyatomic ions and their Names

As the name suggests, the polyatomic ions are cations or anions that contain more than one element. Complete Table 3 by providing names of polyatomic ions, their chemical symbols and charges.

Part 2D: Naming Ionic compounds

Derive the names of the ionic compounds based on the rules discussed above and complete Table 4.

Part 2E: Deriving chemical formulas of Ionic compounds

In the previous section, we learned about naming ionic compounds. In this activity, we will learn to derive the chemical formulas of ionic compounds. In order to derive chemical formulas, we will follow the following steps. Complete the Table 5 by deriving the chemical formulas.

Exploration 3: Covalent compounds

Part 3A: Naming Covalent compounds and deriving chemical formula

Based on the information given here, complete the Table 6.

Complete the following table (Table 7) by deriving chemical formulas of covalent compounds based on the name of the compound.

Exploration 4: Flames Test- Identifying the Cation

Materials: Solids or 1 M solutions of lithium chloride (LiCl), potassium chloride (KCl), copper sulfate (CuSO₄), calcium chloride (CaCl₂), sodium chloride (NaCl), 1M hydrochloric acid (HCl), DI water, metal loop, burner

Method:

Questions:

1. What is the color of the flame of the unknown solution?
2. The unknown contains one of the cations in the table above.  Based on the color of the flame, what cation is present in the unknown?

Exploration 5: Appearance and Solubility of Ionic and Covalent Compounds

Materials: weigh plates, CaCl₂, NaCl, sucrose, stearic acid, 8 test tubes, test tube holder, spatula, water, ethanol, and parafilm.

Method:

Questions:

1. Based on the appearance of the compounds, which would you expect to be ionic and which would you expect to be covalent?
2. Based on the results of the solubility study, which compounds do you expect to be ionic and which compounds do you expect to be covalent.

Exploration 6: Conductivity of Ionic and covalent compounds

Materials: Water soluble compounds from Exploration 5 and a conductivity meter

Method:

Questions:

1. Do your identifications of the compounds as ionic or covalent from the conductivity study match the results from Exploration 5?  If not, which ones do not match?
2. Based on the results of both Explorations 5 and 6, which of your substances are ionic and which are covalent.

Exploration 7: Draw Lewis structures of simple ionic and covalent compounds

Part 7A: Lewis Symbols for Ionic Compounds

Draw the Lewis symbols to show electron transfers for the following compounds:  

Part 7B: Lewis Symbols for Covalent Compounds

Draw Lewis structures of the following molecules and compounds. Then, comment on the VSPER shape these molecules would have.

Reflection:

Reflect on 4 key concepts that you learned in this lab exercise.  Be specific in your answer (this should require 5-10 sentences).