A Markov chain is a discrete random process with the property that the next state depends only on the current state (wikipedia). A Markov chain is a discrete random process with the property that the next state depends only on the current state (wikipedia). So $P(X_n | X_1, X_2, \ldots X_n-1) = P(X_n | X_{n-1})$.
Some people find molecules and compounds confusing. Here's how to remember the difference. If you join two different chemical elements together, you can often make a completely new substance. Glue two atoms of hydrogen to an atom of oxygen and you'll make a single molecule of water.
These types of crystals are made up of small molecules that hold themselves together using weak electrical forces. There is also quite a bit of space between these small molecules. These types of crystals have low melting points and are good insulators. Diamonds. Diamonds are a good example of a crystal that is made up of large molecules. They are created from a large molecule that is put together in three dimensions. Diamonds are made only of carbon atoms, and each carbon atom is bonded to four other carbon atoms that are at equal distance to each other and are grouped around it.