Magnesium is in chlorophyll which makes plants green and enables plants to grow by using sunlight. Aluminum is very useful because it is an abundant, lightweight metal which doesn't corrode. Silicon is one of the most common elements in rocks, sand, and dirt. Computers chips are mostly silicon. Phosphorus is one of the major elements in bones.
Sulfur makes egg yolks yellow and makes rotten eggs stink.
Chlorine is very active and is used in acids and bleaches which kill germs. Chlorine and sodium make salt. Argon is the inert gas in regular light bulbs. Calcium is in milk, bones, teeth, shells, pearls, chalk, plaster, cement, and other white things. Scandium causes the blue-green color in aquamarine gems.