Magnesium is a fairly strong, silvery-white, light-weight metal. It is protected by a thin layer of oxide which is fairly impermeable and hard to remove. Magnesium reacts with water at room temperature, though it reacts much more slowly (for example) than calcium. When it is submerged in water hydrogen bubbles will almost unnoticably begin to form on the surface of the metal, though if powdered it will react much more rapidly. We can add that magnesium reacts with hydrochloric acid, too. Sometimes the metal becomes so hot that can't be touch. The reaction between Mg and hydrochloric acid can occur faster with higher temperature. Magnesium is a highly flammable metal, but while it is easy to ignite when powdered or shaved into thin strips, it is difficult to ignite in mass or bulk. Once ignited it is difficult to put out. Magnesium is able to burn with nitrogen and carbon dioxide. In the first case we can get magnesium nitride and the second give us magnesium oxide and carbon. Magnesium compounds are typically white crystals. Most are soluble in water, providing the sour-tasting magnesium ion Mg2+.When the metal burns in the air it produces a brilliant white light. That was something necessary for photography many centuries ago. Later, magnesium ribbon was used in electrically ignited flash bulbs. Today people still use magnesium metal in the metallurgy and manufacture of fireworks.
Magnesium ion in large amounts is an ionic laxative, and magnesium sulfate is sometimes used for this purpose. There is one modern name - 'milk of magnesia' which means water with suspension of one of the few irresolvable magnesium compounds. Usually that water is used as au antacid.
Magnesium, when glowing white, has many chemical properties which can't be possess at lower temperatures. It also becomes more toxic, although this is of little practical importance, because the high temperature alone generally prevents human contact.