[填空题]
Lithium is a low-den*tqs pxq 4kre:r;m468 ellk;rsi)h m vy/1y5fbjty alkali metal that reacts vigorously with water.
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.
