Question

Cobalt, a transition metal, forms both the \(\mathrm{Co}^{2+}\) and \(\mathrm{Co}^{3+}\) ions. Write the correct formulas, and give the name for the oxides formed by the two different ions.

Short answer

The oxides formed by the two different cobalt ions are cobalt(II) oxide with the formula \(\mathrm{CoO}\), and cobalt(III) oxide with the formula \(\mathrm{Co_2O_3}\).

Step-by-step solution

Determine the charge of the oxygen ion

In a compound, the oxygen ion typically has a charge of -2 (written as \(\mathrm{O}^{2-}\)).

Find the formula for the oxide formed by \(\mathrm{Co}^{2+}\)

To find the chemical formula of the oxide formed by \(\mathrm{Co}^{2+}\), we need to form a neutral compound by balancing the positive and negative charges. Since the cobalt ion has a charge of +2 (\(\mathrm{Co}^{2+}\)) and the oxygen ion has a charge of -2 (\(\mathrm{O}^{2-}\)), we can simply combine one cobalt ion with one oxygen ion to form a neutral compound: \(\mathrm{Co}^{2+}\) + \(\mathrm{O}^{2-}\) = \(\mathrm{CoO}\)

Name the oxide formed by \(\mathrm{Co}^{2+}\)

The oxide formed by \(\mathrm{Co}^{2+}\) is called cobalt(II) oxide. The roman numeral II indicates the charge of the cobalt ion in the compound.

Find the formula for the oxide formed by \(\mathrm{Co}^{3+}\)

To find the chemical formula of the oxide formed by \(\mathrm{Co}^{3+}\), we need to balance the positive and negative charges in the compound. The cobalt ion has a charge of +3 (\(\mathrm{Co}^{3+}\)) and the oxygen ion has a charge of -2 (\(\mathrm{O}^{2-}\)). To balance the charges, we need two cobalt ions with a total charge of +6 and three oxygen ions with a total charge of -6: 2(\(\mathrm{Co}^{3+}\)) + 3(\(\mathrm{O}^{2-}\)) = \(\mathrm{Co_2O_3}\)

Name the oxide formed by \(\mathrm{Co}^{3+}\)

The oxide formed by \(\mathrm{Co}^{3+}\) is called cobalt(III) oxide. The roman numeral III indicates the charge of the cobalt ion in the compound. To summarize, the two cobalt oxides formed by the given ions, their corresponding formula, and their names are: 1. Cobalt(II) oxide: \(\mathrm{CoO}\) 2. Cobalt(III) oxide: \(\mathrm{Co_2O_3}\)

Key concepts

Transition Metals

Transition metals are fascinating elements found in the middle block of the periodic table. These metals, including cobalt, have unique characteristics that make them indispensable in both industrial applications and chemical reactions. A key feature of transition metals is their ability to form ions with different oxidation states, or charges. This is due to the partially filled d orbitals that can lose or share electrons more easily.

Some common properties of transition metals include:

• They typically exhibit more than one oxidation state.
• They often form colored compounds.
• They can act as catalysts in reactions.
• They generally have high melting and boiling points.

Cobalt, as a transition metal, showcases many of these traits. It can form extendash capable of having +2 or +3 charges. This versatility allows for the formation of different compounds like cobalt(II) oxide and cobalt(III) oxide.

Chemical Formulas

Chemical formulas are symbolic representations that describe the types and numbers of elements in a compound. For students, understanding how to write chemical formulas is crucial, as it lays the groundwork for learning about chemical reactions and equations.

When constructing chemical formulas, especially for ionic compounds like cobalt oxides, remember the key rule: the total charge must be neutral. You balance positive and negative charges by adjusting the number of each ion. Here’s a quick look at the chemical formula creation for cobalt oxides:

• For cobalt(II) oxide, with extendash Combine one extendash yielding the neutral compound extendash
• For cobalt(III) oxide, note that each cobalt ion is +3 and each oxygen ion is -2. To balance charges:
  • Required: 2 cobalt ions and 3 oxygen ions to achieve charge neutrality, leading to formula

By practicing writing formulas, you can sharpen your understanding and application of basic chemical principles related to ionic bonding.

Oxidation States

Understanding oxidation states is essential to grasp the behavior of elements, especially transition metals. The oxidation state refers to the charge an atom would have if all bonds were ionic. For transition metals, their oxidation states are not fixed; they can vary due to the multiple valence electrons available for bonding.

Cobalt is an excellent example of this. It commonly exhibits a +2 or +3 oxidation state:

• extendash cobalt(II) oxide because cobalt loses two electrons, balancing the -2 charge of oxygen.
• extendash balancing the -6 charge of two oxide ions.

Determining the correct oxidation state is a crucial step in writing chemical names and formulas. Use the compound's name to identify the metal's oxidation state denoted by Roman numerals. This is why and Considering oxidation states is fundamental in predicting chemical reactivity and forming stable compounds.