How many electrons does transition metals lose?

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Figure \(\PageIndex{1}\) (Credit: User:Cepheus/Wikimedia Commons, modified by CK-12 Foundation; Source: http://commons.wikimedia.org/wiki/File:Periodic_table.svg(opens in new window); License: Public Domain)

How do transition metals form ions?

The transition metals are an interesting and challenging group of elements. They have perplexing patterns of electron distribution that do not always follow the electron filling rules. Predicting how they will form ions is also not always obvious.

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How do transition metals form ions?
Transition Metal Ions
Incoming electrons fill lowest value orbitals first.
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How many electrons do transition metals have?
Do transition elements lose electrons?
Why do transition metals lose s electrons first?
Do transition metals lose electrons easily?

Transition Metal Ions

Transition metals belong to the \(d\) block, meaning that the \(d\) sublevel of electrons is in the process of being filled with up to ten electrons. Many transition metals cannot lose enough electrons to attain a noble-gas electron configuration. In addition, the majority of transition metals are capable of adopting ions with different charges. Iron, which forms either the \(\ce{Fe^{2+}}\) or \(\ce{Fe^{3+}}\) ions, loses electrons as shown below.

\[\begin{array}{lcl} \ce{Fe} & \rightarrow & \ce{Fe^{2+}} + 2 \ce{e^-} \\ \left[ \ce{Ar} \right] \: 3d^6 \: 4s^2 & & \left[ \ce{Ar} \right] \: 3d^6 \end{array}\nonumber \]

\[\begin{array}{lcl} \ce{Fe} & \rightarrow & \ce{Fe^{3+}} + 3 \ce{e^-} \\ \left[ \ce{Ar} \right] \: 3d^6 \: 4s^2 & & \left[ \ce{Ar} \right] \: 3d^5 \end{array}\nonumber \]

According to the Aufbau process, the electrons fill the \(4s\) sublevel before beginning to fill the \(3d\) sublevel. However, the outermost \(s\) electrons are always the first to be removed in the process of forming transition metal cations. Because most transition metals have two valence electrons, the charge of \(2+\) is a very common one for their ions. This is the case for iron above. A half-filled \(d\) sublevel \(\left( d^5 \right)\) is particularly stable, which is the result of an iron atom losing a third electron.

Figure \(\PageIndex{2}\): A. Rust is a complex combination of oxides of iron, among them iron (III) oxide, \(\ce{Fe_2O_3}\). B. Iron (II) sulfate, \(\ce{FeSO_4}\), has been known since ancient times as green vitriol and was used for centuries in the manufacture of inks. (Credit: (A) Paulnasca; (B) Ben Mills (Wikimedia: Benjah-bmm27); Source: (A) http://commons.wikimedia.org/wiki/File:Rust_screw.jpg(opens in new window); (B) http://commons.wikimedia.org/wiki/File:Iron%2528II%2529-sulfate-heptahydrate-sample.jpg(opens in new window); License: CC by 2.0(opens in new window); Public Domain)

Some transition metals that have relatively few \(d\) electrons may attain a noble-gas electron configuration. Scandium is an example.

\[\begin{array}{lcl} \ce{Sc} & \rightarrow & \ce{Sc^{3+}} + 3 \ce{e^-} \\ \left[ \ce{Ar} \right] \: 3d^1 \: 4s^2 & & \left[ \ce{Ar} \right] \end{array}\nonumber \]

Others may attain configurations with a full \(d\) sublevel, such as zinc and copper.

\[\begin{array}{lcl} \ce{Zn} & \rightarrow & \ce{Zn^{2+}} + 2 \ce{e^-} \\ \left[ \ce{Ar} \right] \: 3d^{10} \: 4s^2 & & \left[ \ce{Ar} \right] \: 3d^{10} \end{array}\nonumber \]

\[\begin{array}{lcl} \ce{Cu} & \rightarrow & \ce{Cu^+} + \ce{e^-} \\ \left[ \ce{Ar} \right] \: 3d^{10} \: 4s^1 & & \left[ \ce{Ar} \right] \: 3d^{10} \end{array}\nonumber \]

The resulting configuration above, with 18 electrons in the outermost principal energy level, is referred to as a pseudo noble-gas electron configuration. It gives particular stability to the \(\ce{Zn^{2+}}\) and \(\ce{Cu^+}\) ions.

Summary

Transition metal ion formation is more complex than simple cation formation.
Transition metal ions often involve rearrangements of both \(d\) and \(s\) electrons.

Review

What block do the transition metals fall in?
When writing the electron configuration for a transition metal, which sublevel (\(s,p,d,f\)) is filled first?
When forming transition metal ions, which sublevel (\(s,p,d,f\)) loses electrons first? What is the pseudo noble-gas electron configuration?

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Incoming electrons fill lowest value orbitals first.

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How many electrons do transition metals have?

The transition metals are able to put up to 32 electrons in their second-to-last shell. Something like gold (Au), with an atomic number of 79, has an organization of 2-8-18-32-18-1. Of course, there are still some rules. No shell can have more than 32 electrons.

Do transition elements lose electrons?

Transition Metal Ions Many transition metals cannot lose enough electrons to attain a noble-gas electron configuration. In addition, the majority of transition metals are capable of adopting ions with different charges. Iron, which forms either the Fe2+ or Fe3+ ions, loses electrons as shown below.

Why do transition metals lose s electrons first?

However, in all the chemistry of the transition elements, the 4s orbital behaves as the outermost, highest energy orbital. When these metals form ions, the 4s electrons are always lost first.

Do transition metals lose electrons easily?

When it comes to transition metals it is a little more complicated, but like many other metals, they also have low electronegativities. Transition metals have (n−1)d and ns orbitals which have many electrons similar in energy, meaning that it is sometimes easy for many of those electrons to be lost.