Quizlet is a free web based Flash Card tool. You can create your own sets and share them with your learners. You do not get feedback on their progress, this is designed as a self checking tool. Alternately learners could create their own sets to help them with concepts they find difficult.
There are apps available for smart devices that allow the card sets to be downloaded and studied. These vary in quality but the good ones can progress check, or offer a nice variety of activities for the learner. On Apple devices try Quizard, A+ and iReview.
This set of flash card covers common chemical elements and their properties. To learn the information in different ways please click on the drop down label.