The alkali metals are the metals in group 1. They do not behave like many everyday metals such as iron. Alkali metals are soft, so lithium, sodium and potassium can be cut with a knife. A freshly cut surface is shiny, but it quickly turns dull as the metal reacts with oxygen in the air. They are stored under oil to keep them away from air and water.
They also have relatively low melting points for metals. Lithium melts at about 181 °C, sodium at about 98 °C and potassium at about 63 °C, whereas iron melts at over 1500 °C. Going down the group the melting points get lower. Lithium, sodium and potassium are also less dense than water, so they float on it.