In chemistry, “earth” is an old name used for certain compounds (oxides) that were difficult to separate into elements

In chemistry, “earth” is an old name used for certain compounds (oxides) that were difficult to separate into elements (and were therefore thought to be elements).

• In chemistry, “earth” is an old name used for certain compounds (oxides) that were difficult to separate into elements (and were therefore thought to be elements).

• Examples are the alkaline earths, from which the alkaline earth elements (group 2) were later isolated.

The term rare earths elements (or usually just “rare earths”) is used for scandium, yttrium, lanthanum, and the lanthanides.

• The term rare earths elements (or usually just “rare earths”) is used for scandium, yttrium, lanthanum, and the lanthanides.

• Rare earths are critical for modern electronic products.

• Currently there is concern because more than 95% of production is in China.

Sample Problem

• Sample Problem

• Of the elements magnesium, Mg, chlorine, Cl, sodium, Na, and phosphorus, P, which has the largest atomic radius? Explain your answer in terms of trends of the periodic table.

Solution

• Solution