It is better when you write the reference.Thanks 3. (5 points) The atomic and io

Question

It is better when you write the reference.Thanks 3. (5 points) The atomic and ionic radii of period 6 transition metals are smaller than would be expected from the general trend. For example, Mo has an atomic radius of 145 pm and W has an atomic radius of 135 pm (actually smaller than the element above it). The reason for this is arn effect known as the lanthanide contraction Research this effect on line (please do not use Wikipedia), and write a paragraph or two defining the lanthanide contraction and how it explains the smaller than expected radii for the elements Hf Hg.

Explanation / Answer

The Lanthanide Contraction describes the atomic radius trend that the Lanthanide series exhibit. Another important feature of the The Lanthanide Contraction refers to the fact that the 5s and 5p orbitals penetrate the 4f sub-shell so the 4f orbital is not shielded from the increasing nuclear change, which causes the atomic radius of the atom to decrease. This decrease in size continues throughout the series.

The Lanthanide Contraction is the result of a poor shielding effect of the 4f electrons. The shielding effect is described as the phenomenon by which the inner-shell electrons shield the outer-shell electrons so they are not effected by nuclear charge. So when the shielding is not as good, this would mean that the positively charged nucleus has a greater attraction to the electrons, thus decreasing the atomic radius as the atomic number increases. The s orbital has the greatest shielding while f has the least and p and d in between the two with p being greater than d.

The Lanthanide Contraction can be seen by comparing the elements with f electrons and those without f electrons in the d block orbital. Pd and Pt are such elements. Pd has 4d electrons while Pt has 5d and 4f electrons. These 2 elements have roughly the same atomic radius. This is due to Lanthanide Contraction and shielding. While we would expect Pt to have a significantly larger radius because more electrons and protons are added, it does not because the 4f electrons are poor at shielding. When the shielding is not good there will be a greater nuclear charge, thus pulling the electrons in closer, resulting in a smaller than expected radius.

reference - JD LEE concise inorganic chemistry

Satyapraksh inorganic chemistry

inorganic chemistry Huheey & Keiter

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