Elements of Life

If you could look inside yourself with a super-powered microscope, you would see that about $96\%$ of your body is made of just four elements: Oxygen ($O$), Carbon ($C$), Hydrogen ($H$), and Nitrogen ($N$). Think of these as the 'flour, sugar, and eggs' of the human recipe. Oxygen is the most common; it helps your cells turn food into energy. Carbon is the 'backbone' of your body, forming the structure of your skin and muscles. Hydrogen is found in the water ($H_2O$) that fills your cells, and Nitrogen is a key part of your DNA, which is the instruction manual for building you!

While the 'Big Four' do most of the work, other elements have very special jobs. Calcium ($Ca$) is the element that makes your bones and teeth hard and strong. Without it, you would be as floppy as a noodle! Iron ($Fe$) has a different job: it lives in your red blood cells. Iron acts like a tiny magnet that grabs Oxygen from your lungs and carries it to the rest of your body. If you don't have enough Iron, you might feel very tired because your body isn't getting the Oxygen it needs to stay active.

The Periodic Table is like a map of all the elements in the universe. Each element has a 'home' on this map. To find our life elements, we look for their Chemical Symbols. For example, Hydrogen is in the top left corner at position $1$. Oxygen is at position $8$. Some symbols are easy, like $C$ for Carbon. Others are tricky, like $Fe$ for Iron, which comes from the Latin word ferrum. Knowing where these elements live helps scientists understand how they react with each other to keep us alive.