The heterogeneous mixture that has very small dispersed particles and stays mixed for a long time is colloid. Because colloid has particles that are small enough to suspended but are as large that they can scatter light.
The isotopes of an element differ in the number or neutrons whereas the number of protons or electrons of a neutral atom stays the same. The molar mass of the element is based on the percent abundances of different isotopes and the individual molar mass of each isotope.
