PROBLEM \(\PageIndex{1}\) At very low temperatures oxygen, O 2 , freezes and forms a crystalline solid. Which best describes these crystals? ionic covalent network metallic amorphous molecular crystals Answer (e) molecular crystals PROBLEM \(\PageIndex{2}\) As it cools, olive oil slowly solidifies and forms a solid over a range of temperatures. Which best describes the solid? ionic covalent network metallic amorphous molecular crystals Answer (d) amorphous PROBLEM \(\PageIndex{3}\) Explain why ice, which is a crystalline solid, has a melting temperature of 0 °C, whereas butter, which is an amorphous solid, softens over a range of temperatures. Answer Ice has a crystalline structure stabilized by hydrogen bonding. These intermolecular forces are of comparable strength and thus require the same amount of energy to overcome. As a result, ice melts at a single temperature and not over a range of temperatures. The various, very large molecules that compose butter experience varied van der Waals attractions of various strengths that are overcome at various temperatures, and so the melting process occurs over a wide temperature range. PROBLEM \(\PageIndex{4}\) Identify the type of crystalline solid (metallic, network covalent, ionic, or molecular) formed by each of the following substances: SiO 2 KCl Cu CO 2 C (diamond) BaSO 4 NH 3 NH 4 F C 2 H 5 OH Answer a covalent network Answer b ionic Answer c metallic Answer d molecular Answer e covalent network Answer f ionic Answer g molecular Answer h ionic Answer i molecular PROBLEM \(\PageIndex{5}\) Identify the type of crystalline solid (metallic, network covalent, ionic, or molecular) formed by each of the following substances: CaCl 2 SiC N 2 Fe C (graphite) CH 3 CH 2 CH 2 CH 3 HCl NH 4 NO 3 K 3 PO 4 Answer a ionic Answer b Covalent network Answer c molecular Answer d metallic Answer e covalent network Answer f molecular Answer g molecular Answer h ionic Answer i ionic PROBLEM \(\PageIndex{6}\) Classify each substance in the table as either a metallic, ionic, molecular, or covalent network solid: Substance Appearance Melting Point Electrical Conductivity Solubility in Water X lustrous, malleable 1500 °C high insoluble Y soft, yellow 113 °C none insoluble Z hard, white 800 °C only if melted/dissolved soluble Answer X = metallic; Y = covalent network; Z = ionic PROBLEM \(\PageIndex{7}\) Classify each substance in the table as either a metallic, ionic, molecular, or covalent network solid: Substance Appearance Melting Point Electrical Conductivity Solubility in Water X brittle, white 800 °C only if melted/dissolved soluble Y shiny, malleable 1100 °C high insoluble Z hard, colorless 3550 °C none insoluble Answer X = ionic; Y = metallic; Z = covalent network PROBLEM \(\PageIndex{8}\) Substance A is shiny, conducts electricity well, and melts at 975 °C. Substance A is likely a(n): ionic solid metallic solid molecular solid covalent network solid Answer (b) metallic solid PROBLEM \(\PageIndex{9}\) Substance B is hard, does not conduct electricity, and melts at 1200 °C. Substance B is likely a(n): ionic solid metallic solid molecular solid covalent network solid Answer (d) covalent network solid Have a video solution request? Let your professors know here. ***Please know that you are helping future students - videos will be made in time for next term's class. Contributors Paul Flowers (University of North Carolina - Pembroke), Klaus Theopold (University of Delaware) and Richard Langley (Stephen F. Austin State University) with contributing authors. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at http://cnx.org/contents/85abf193-2bd...a7ac8df6@9.110 ). Adelaide Clark, Oregon Institute of Technology Feedback Think one of the answers above is wrong? Let us know here .