Q 6P - Chemistry: Molecular Nature Of Matter And Change

Question

Question: (a) What is the lanthanide contraction? 

(b) How does it affect atomic size down a group of transition elements? 

(c) How does it influence the densities of the Period 6 transition elements?

Step-by-Step Solution

Answer

1. The lanthanide contraction occurs when the atomic size of transition elements.
2. Because an element in Period 6 is isolated from one in Period 5.
3. Because there is just a modest difference in atomic size between Periods 5 and 6, densities.

Step 1: Define transition elements

Any of several chemical elements with two instead of one valence electrons (i.e., electrons that can participate in the creation of chemical bonds).

Step 2: For lanthanide concentration

a)

The lanthanide contraction occurs when the atomic size of transition elements Period 6 and Period 7atoms shrink due to the presence of fourteen $4\mathrm{f}$ electrons that protect the outer electrons from the rise in nuclear charge caused by the addition of fourteen protons.

Step 3: For atom size down a group

b)

Because an element in Period 6 is isolated from one in Period 5 by  32 electrons instead of 18 due to the hidden $4\mathrm{f}$ sublevel, which includes 14  electrons, the atomic size grows from Period 4 to 5, but then pauses.

Step 3: For densities of 6 th transition element

c) 

Because there is just a modest difference in atomic size between Periods 5  and 6, densities increase dramatically as you move along a set of transition elements. Gold, rhenium, osmium, and iridium are among the elements with the highest densities known.