 Group 1 metals are very reactive because they have low ionization energies. One of the ways that indicates this high reactivity is the way that we store the metals. Group 1 metals are typically stored under kerosene or mineral oil to prevent or limit the reaction with the oxygen in the air. Let's look at some of the physical properties for Group 1 metals. We'll start out with lithium. The lithium is coated at this point in time with a layer of both the oxide and the nitride. And we end up with a fairly dull gray appearance. Group 1 metals tend to be relatively soft and we can easily cut the metal with a knife. What we can do is we can see the shiny metallic surface underneath. If we bring in a conductivity tester, we can see that the lithium is an excellent conductor of electricity. If we add a piece of lithium to the water, one of the things that we notice is the fact that the lithium floats. Group 1 metals are less dense than water. We also see that the lithium reacts very rapidly with the water. This is a single displacement reaction producing hydrogen gas and lithium hydroxide. The lithium hydroxide is very water soluble and dissolves in the water. The hydrogen gas escapes. If we trap some of the gas in a test tube, we can test that the gas is actually hydrogen by testing its flammability. We can test that the lithium hydroxide has been produced by adding an acid-based indicator. If we add some phenothaline, phenothaline is coalescent acid and red, purple and base. We can tell that the solution is basic due to the formation of the lithium hydroxide.