Oxygen, chlorine, silicon, aluminum, iron, phosphorous, calcium, sodium, potassium, magnesium, hydrogen, and carbon are true building blocks. They combine readily with other elements to form compounds. Recognizing these elements as building blocks is essential to the study of science. That's Everywhere Of all the elements, chlorine is among the most active. That's why chlorine is often found in some surprising places and products.
Chlorine makes up two percent by weight of all sea water on Earth.
Chlorine compounds are used in the production of thousands of consumer goods, pharmaceuticals, and industrial products. Or it can be extremely simple. Without chlorine compounds, we wouldn't have many of the products and services that we often take for granted. Because water is so basic to our existence, ensuring safe drinking water also would be a natural topic for student exploration and class discussion. For example, the Latin American cholera epidemic in the news over the past year is a shocking reminder of what can happen when drinking water is not adequately disinfected.