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  • 0:04 A Natural Compound
  • 0:27 Copper II Oxide Formula
  • 1:33 Copper II Oxide Properties
  • 2:41 Copper II Oxide Structure
  • 3:06 Lesson Summary
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Copper II Oxide: Formula, Properties & Structure

Lesson Transcript
Matthew Bergstresser

Matthew has a Master of Arts degree in Physics Education. He has taught high school chemistry and physics for 14 years.

Expert Contributor
Christianlly Cena

Christianlly has taught college physics and facilitated laboratory courses. He has a master's degree in Physics and is pursuing his doctorate study.

Copper(II) oxide is an ionic compound consisting of copper and oxygen ions. In this lesson, we will discuss its formula, physical properties of the compound, and its structure. Updated: 02/02/2021

A Natural Compound

Just under 0.007% of Earth's crust is comprised of copper. Around 46% of Earth's crust is oxygen, and just over 20% of Earth's atmosphere is oxygen. These two elements can come together chemically to form copper(II) oxide. Let's figure out how these two elements combine and discuss the properties and structure of the compound.

Copper(II) Oxide Formula

The chemical combination of a metal and a non-metal generates an ionic compound. We can determine the formula for an ionic compound based on how many electrons the metal atom loses and how many electrons the non-metal atom gains. The Roman numeral II tells us the electric charge, or oxidation state, of the copper ion, which is +2. This means each copper atom loses two electrons to form the ion Cu+2.

Oxygen is a non-metal and will always gain two electrons, giving it the oxidation state -2. Since each oxygen atom has two extra electrons, the oxide ion is formed, which is O-2.

All ionic compounds have to be electrically neutral, which means the ratio of each element in the compound must contribute enough charge to cancel the charge of the other ion. In the case of the copper(II) ion and the oxygen ion, we can see both ions have equal and opposite charges. This means we only need one of each ion to form the neutral compound copper(II) oxide, which is CuO. Let's discuss the properties of copper(II) oxide.

Copper(II) Oxide Properties

When you watch police television dramas you might hear them describe the characteristics of the person they're looking for. They might note their physical appearance, including height, weight, eye color, and so on. They also might also note their personality. Are they friendly, reserved, or generally cranky? We can use this analogy to understand the types of properties of a compound, including its physical characteristics and its chemical reactivity. Let's pretend we're a private detective searching for the copper(II) oxide compound like we're searching for a person.

We're on the lookout for an ionic compound with the following physical characteristics:

  • Molar mass equal to 78.92 g/mole
  • Black or dark brown solid, possibly in powder form
  • Density of around 6.31 g/cm3
  • Melts at just over 1200°C
  • Boils at around 2000°C

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Additional Activities

Copper II Oxide: True or False Activity

This activity will help you assess your knowledge of the chemical formula and physical properties of copper(II) oxide.


Determine whether the following statements are true or false. To do this, print or copy this page on a blank paper and underline or circle the answer.

True | False 1. The chemical element copper is a reddish metal that constitutes 46 percent of the Earth's crust.

True | False 2. In ionic bonds, a metal loses electrons while the nonmetal accepts those electrons.

True | False 3. As the copper atom loses electrons, it then becomes negatively charged.

True | False 4. The total charge within an ionic compound must be +2.

True | False 5. The chemical reaction between oxygen and copper forms copper(II) oxide.

True | False 6. Oxidation states are typically represented by integers, which can either be positive or negative.

True | False 7. Copper(II) oxide is made up of atoms arranged in a lattice, held together via electrostatic attraction.

True | False 8. CuO boils over 2000 degrees Celsius; it is highly-flammable and dissolves well in water.

Answer Key

  1. False, because the correct statement is: The chemical element copper is a reddish metal that constitutes 0.007 percent of the Earth's crust.
  2. True
  3. False, because the correct statement is: As the copper atom loses electrons, it becomes positively charged.
  4. False, because the correct statement is: The total charge within an ionic compound must be 0 or neutral.
  5. True
  6. True
  7. True
  8. False, because the correct statement is: CuO boils over 2000 degrees Celsius; it is non-flammable and insoluble in water.

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