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Transition Metal plays an important role in our society. For example, copper lets us have the electricity in our homes; gold plays an important role in our economy. It is important that we understand the periodic trends of these important metals.
Transition metals have high melting points due to strong metallic bonds. Number of unpaired electrons in the outermost shell indicates the strength of the metallic bonds. Therefore, the more unpaired electrons are present, the higher melting point will be. The first 4 elements in a row always have the highest melting points. However, as the unpaired d orbital electrons pair up, the melting point decreases. The last 5 elements in a row have a lower melting point than the first 4 elements. The last element in each row has the lowest melting point because the d orbital electrons are filled.
|Example 1: Scandium|
Lets look at an example between Scandium (Sc) and Zinc (Zn).
Sc: [Ar] 4s² 3d¹ lets take a look at the d orbital:
For Sc we see that there is only one electron in the d-orbital and that electron is unpaired.
Melting point of Sc is 1814 K.
|Example 2: Zinc|
Now let’s look at Zinc (Zn)
Zn: [Ar] 4s² 3d¹? lets take a look at the d orbital:
For Zn we see that there are no unpaired electrons in the d- orbital.
The melting point of Zn is 692.93 K, which is significantly lower than Sc at 1814 K. This example shows that the number of unpaired electrons does effect the melting point.
Electrode Potential is the potential of receiving a electron. The electron potential increases across the series for transition metals. H+ can reduce all transition metals except Cu because Cu has a higher reduction potential than H+. Lets look at the half reactions and the electrode potential for H+, Zn2+ which is a transition metal and Cu which is the exception to the rule.
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