---
title: "A student screens materials for use in a high-temperature electrical feedthrough. The student uses an operational model in which a bond between a metal and a nonmetal has predominantly ionic character when \\(\\Delta\\chi>1.7\\). A bond between two nonmetals is polar covalent when \\(0.5\\leq\\Delta\\chi\\leq1.7\\) and nonpolar covalent when \\(\\Delta\\chi"
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url: "https://nerd-notes.com/ubq/120040/"
date_modified: "2026-08-21T08:40:54+00:00"
---

# A student screens materials for use in a high-temperature electrical feedthrough. The student uses an operational model in which a bond between a metal and a nonmetal has predominantly ionic character when \(\Delta\chi>1.7\). A bond between two nonmetals is polar covalent when \(0.5\leq\Delta\chi\leq1.7\) and nonpolar covalent when \(\Delta\chi

A student screens materials for use in a high-temperature electrical feedthrough. The student uses an operational model in which a bond between a metal and a nonmetal has predominantly ionic character when \(\Delta\chi>1.7\). A bond between two nonmetals is polar covalent when \(0.5\leq\Delta\chi\leq1.7\) and nonpolar covalent when \(\Delta\chi<0.5\). A material composed only of metals is evaluated for metallic bonding by using its conductivity and mechanical behavior.

| Sample | Types of constituent elements | Electronegativity values, \(\chi\) | Solid conductivity, \(\sigma\) \((\text{S}\,\text{m}^{-1})\) | Conductivity after melting, \(\sigma\) \((\text{S}\,\text{m}^{-1})\) | Mechanical behavior as a solid |
|---|---|---|---|---|---|
| \(\text{MgO}\) | metal and nonmetal | \(1.3,\ 3.4\) | \(<1\times10^{-10}\) | \(3\times10^{2}\) | Shatters under applied force |
| \(\text{ICl}\) | two nonmetals | \(2.7,\ 3.2\) | \(<1\times10^{-10}\) | \(<1\times10^{-10}\) | Shatters under applied force |
| \(\text{Cu-Ni}\) alloy | two metals | \(1.9,\ 1.9\) | \(2\times10^{6}\) | \(1\times10^{6}\) | Deforms without shattering |

Which assignment of dominant bonding character is most consistent with both the model and the data?

- **A.** \(\text{MgO}\): ionic; \(\text{ICl}\): nonpolar covalent; \(\text{Cu-Ni}\): metallic
- **B.** \(\text{MgO}\): polar covalent; \(\text{ICl}\): polar covalent; \(\text{Cu-Ni}\): metallic
- **C.** \(\text{MgO}\): ionic; \(\text{ICl}\): polar covalent; \(\text{Cu-Ni}\): nonpolar covalent
- **D.** \(\text{MgO}\): ionic; \(\text{ICl}\): polar covalent; \(\text{Cu-Ni}\): metallic

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120040/*