[填空题]
Lithium is a low-density alkali metal t f2ndzw+mo* w-hat reacts vigorously with wkiv9a*r)5rc3 jg3)6ptkxx va ater.
1.Given the below data and referring to the periodic table, calculate the relative abundances of the isotopes of lithium.
Isotope is $^6$Li, Atomic Mass is 6.015
Isotope is $^7$Li, Atomic Mass is 7.016
The relative abundances of each isotope are % for Li-6 and %for Li-7
2.State the definition of an isotope.
3.Outline the concept of relative abundance.
