What three obstacles did dmitri mendeleev face in his life

~He was working without prior knowledge toward creating a periodic table of elements that had been done in Europe in the 1860s

~ scandal when he got married to his second wife before he divorced his first wife

~he was working with data that was not very precise (technology didn't exist at the time to make accurate measurements (e.g., weights) for the things he was working on.) Many elements had also not been discovered yet, so he had to guess at a lot of things when making his conclusions.