The information below refers to six isotopes. How many elements are represented in this group of isotopes? Atomic number Mass number

19 39

6 13

6 12

19 41

82 207

82 206

There are 3 elements (6; 12) (19; 39) and (82; 207)

There are 3 isotopes (6; 13) (19; 41) and (82; 206)

Explanation:

Step 1:

Isotopes have the same atomic number but a different mass number

The element with number 19 is Potassium

Potassium has a mass number of 39 g/mol

This is the element potassium and is not an element

41C has mass number of 41 g/mol and is an isotope

The element with number 6 is carbon

Carbon has a mass number of 12 g/mol

13C has a mass number of 13 g/mol and is an isotope

The element with number 82 is lead

Lead has a mass number of 207 g/mol

206Pb has a mass number of 206 g/mol and is an isotope

There are 3 elements (6; 12) (19; 39) and (82; 207)

There are 3 isotopes (6; 13) (19; 41) and (82; 206)