Question

Write electron configurations for the following transition metals and their ions. a. \(\mathrm{Co}, \mathrm{Co}^{2+}, \mathrm{Co}^{3+}\) b. \(\mathrm{Pt}, \mathrm{Pt}^{2+}, \mathrm{Pt}^{4+}\) c. \(\mathrm{Fe}, \mathrm{Fe}^{2+}, \mathrm{Fe}^{3+}\)

Short answer

a. Co: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^7}\); Co²⁺: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^7}\); Co³⁺: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^6}\) b. Pt: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}, 4p^6, 5s^2, 4d^{10}, 5p^6, 6s^2, 4f^{14}, 5d^{9}}\); Pt²⁺: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}, 4p^6, 5s^2, 4d^{10}, 5p^6, 4f^{14}, 5d^{8}}\); Pt⁴⁺: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}, 4p^6, 5s^2, 4d^{10}, 5p^6, 4f^{14}, 5d^{6}}\) c. Fe: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^6}\); Fe²⁺: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^6}\); Fe³⁺: \(\mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^5}\)

Step-by-step solution

Neutral Cobalt (Co) electron configuration

To write the electron configuration for the neutral Cobalt atom, we first note its atomic number (27). Using the periodic table, we determine the filling order of orbitals. The electron configuration can be written as: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^7} \]

Cobalt(II) (Co²⁺) electron configuration

To write the electron configuration for Co²⁺, we need to remove two electrons from the neutral Co atom configuration. Electrons are removed first from the 4s orbital. So, Co²⁺ configuration is: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^7} \]

Cobalt(III) (Co³⁺) electron configuration

To write the electron configuration for Co³⁺, we need to remove three electrons from the neutral Co atom configuration. After removing 2 electrons from the 4s orbital, we remove the third electron from the 3d orbital. So, Co³⁺ configuration is: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^6} \] b. Platinum (Pt), Platinum(II) (Pt²⁺), Platinum(IV) (Pt⁴⁺)

Neutral Platinum (Pt) electron configuration

To write the electron configuration for the neutral Platinum atom, we first note its atomic number (78). Using the periodic table, we determine the filling order of orbitals. The electron configuration can be written as: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}, 4p^6, 5s^2, 4d^{10}, 5p^6, 6s^2, 4f^{14}, 5d^{9}} \]

Platinum(II) (Pt²⁺) electron configuration

To write the electron configuration for Pt²⁺, we need to remove two electrons from the neutral Pt atom configuration. Electrons are removed first from the 6s and then from 5d orbital. So, Pt²⁺ configuration is: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}, 4p^6, 5s^2, 4d^{10}, 5p^6, 4f^{14}, 5d^{8}} \]

Platinum(IV) (Pt⁴⁺) electron configuration

To write the electron configuration for Pt⁴⁺, we need to remove four electrons from the neutral Pt atom configuration. After removing 2 electrons from 6s and 5d orbitals, we remove another 2 electrons from the 5d orbital. So, Pt⁴⁺ configuration is: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}, 4p^6, 5s^2, 4d^{10}, 5p^6, 4f^{14}, 5d^{6}} \] c. Iron (Fe), Iron(II) (Fe²⁺), Iron(III) (Fe³⁺)

Neutral Iron (Fe) electron configuration

To write the electron configuration for the neutral Iron atom, we first note its atomic number (26). Using the periodic table, we determine the filling order of orbitals. The electron configuration can be written as: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^6} \]

Iron(II) (Fe²⁺) electron configuration

To write the electron configuration for Fe²⁺, we need to remove two electrons from the neutral Fe atom configuration. Electrons are removed first from the 4s orbital. So, Fe²⁺ configuration is: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^6} \]

Iron(III) (Fe³⁺) electron configuration

To write the electron configuration for Fe³⁺, we need to remove three electrons from the neutral Fe atom configuration. After removing 2 electrons from the 4s orbital, we remove the third electron from the 3d orbital. So, Fe³⁺ configuration is: \[ \mathrm{1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^5} \]

Key concepts

Transition Metals

Transition metals are a group of elements found in the center of the periodic table, specifically in groups 3 to 12. They include elements like Iron (Fe), Cobalt (Co), and Platinum (Pt). One of their defining features is having partially filled d orbitals, which affects their chemical properties. This characteristic enables them to form compounds with variable oxidation states and to act as catalysts in various chemical reactions.
Another intriguing aspect is that their electron configurations involve filling the d subshell after the s orbital of the next energy level. This creates some unique configurations as seen in examples such as Cobalt (Co) with an atomic number of 27:

• Neutral Cobalt (Co): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷

Understanding this helps in predicting the behavior of transition metals in chemical reactions, especially when they are ionized.

Atomic Number

The atomic number of an element is a fundamental concept in chemistry. It is defined as the number of protons found in the nucleus of an atom. This number determines the identity of the element as well as its position in the periodic table.
For example, Iron (Fe) has an atomic number of 26, meaning each atom of Iron has 26 protons. The atomic number also indicates the number of electrons in a neutral atom, which is crucial for determining the electron configuration.

• Iron (Fe) has an electron configuration that reflects its atomic number as follows: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

Thus, understanding the atomic number helps in predicting electron arrangement in atoms and is essential for writing electron configurations.

Orbital Filling Order

The orbital filling order is a guideline that dictates the sequential order in which electrons are placed into orbitals in an atom. It generally follows the Aufbau principle where electrons occupy the lowest energy orbital available. The order can be remembered using the n+l rule where n is the principal quantum number and l is the azimuthal quantum number.
Here's how it begins:

• 1s, 2s, 2p, 3s
• 3p, 4s, 3d, 4p, 5s
• 4d, 5p, 6s, 4f, 5d

For transition metals like Platinum (Pt) with an atomic number of 78, the configuration is relatively complex: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰, and so on. Understanding this order helps in predicting electron configurations for neutral atoms and ions.

Ion Electron Configuration

Ion electron configurations are similar to those of neutral atoms but require the removal or addition of electrons. This process helps form ions, which are charged particles. Typically, transition metals lose electrons from their outermost s orbital before losing from the d orbital.
For example, when you create an ion of Iron (Fe), you remove electrons:

• For Iron (II) ion (Fe²⁺), remove 2 electrons from the 4s orbital: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶
• For Iron (III) ion (Fe³⁺), remove 3 electrons (2 from 4s and 1 from 3d): 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵

By following this method, you can predict the electron configurations for ions of transition metals, which often differ from those of their neutral counterparts.