Question

rare earth elements
replace each question with a full sentence answer the
question

1. how many rare earth elements are there?
2. c. define trans - uranium
3. d. the rare earth metals are found in group ______ and

periods ____ and ____.

Explanation:

Question 1:

To answer how many Rare Earth elements there are, we recall that Rare Earth elements consist of the 15 lanthanides plus scandium and yttrium. So we calculate \(15 + 2=17\). Then we form a full sentence.

To define trans - uranium, we recall that trans - uranium elements are those with an atomic number greater than that of uranium (which is 92). We then form a full - sentence definition.

Rare Earth metals (lanthanides) are found in group 3 of the periodic table, and in periods 6 and 7 (scandium and yttrium are also in group 3, with scandium in period 4 and yttrium in period 5, but the main lanthanide series is in period 6 and actinides (sometimes considered in rare earth discussions) in period 7; for the lanthanide - based rare earths, group 3 and periods 6 and 7 is a common description). We form a full sentence with the blanks filled.

Answer:

There are 17 Rare Earth elements (15 lanthanides plus scandium and yttrium).

Question 2 (c):