Investigation 5 Experience 3: Solids Analysis

Investigation 5 Experience 3

• Reminders: Cell phones off and put away during class. Request an e-hall pass before leaving the classroom. No food or drinks (besides water) in the classroom.

Agenda

• Demo
• Virtual Lab
• Explanation
• Skill Check 5.3

Demo

• Observe crystals, focusing on physical properties of ionic and molecular solids.

Virtual Lab: Tough Tools

• Navigate to SAVVAS and open the Virtual Lab: Tough Tools.
• Evaluate the properties of three different solids to determine which is best for high-speed cutting tools.
• Record observations and answer questions in handout.

Virtual Lab: Tough Tools - Questions

• Explain melting point order of tested solids based on their molecular structure (ionic, molecular, or covalent network).
• Relate electron flow and molecular structure of tested solids to their electrical conductivity.
• Choose hardness, thermal conductivity, or solubility in water and discuss how this property relates to the molecular structure of one of the tested solids.
• Identify the most useful solid for a high-speed cutting tool and explain why.
• Determine whether silicon dioxide, naphthalene, or cobalt (II) chloride would be best for a heat-resistant pigment application and explain.

Comparing Ionic and Molecular Compounds

• Molecular compounds: atoms share electrons through covalent bonds; the representative unit is a molecule.
• Ionic compounds: ions held together by electrostatic forces; the representative unit is the formula unit.

Representative Units

• Molecular compounds: collection of water molecules; molecule of water; chemical formula.
• Ionic compounds: array of sodium ions and chloride ions; formula unit of sodium chloride; chemical formula.

Determining Compound Type

• Use the periodic table to determine compound type and bond types.
• Ionic compounds are composed of metals and nonmetals, while molecular compounds are composed of nonmetals.

Properties of Ionic and Molecular Compounds

• Molecular Compounds: Weak dispersion or weak hydrogen forces, low melting points, volatile.
• Ionic Compounds: Strong ionic forces, high melting points, not volatile.

Covalent Network Solids

• Covalent network solids are held together by covalent bonds, resulting in high melting points.
• Allotropes are different physical forms of the same element (e.g., carbon nanotubes, graphite, diamond, fullerenes).

Physical Properties of Substances

• How materials are designed for specific functions.
• Which solid is most useful for making a high-speed cutting tool?

Checkpoint

• Identify unknown white solid as ionic, molecular, or covalent network solid.

Skill Check 5.3

• Log onto Formative using school account.
• Complete Skill Check 5.3 independently.
• Work on Continuous Improvement.
• Due by 11:59 PM.