The Properties of Water

With its polar nature, powerful cohesion, and universal solvency, water is the unsung hero of biology

The Dive

Water is made up of two small hydrogen atoms and one large oxygen atom, held together by strong polar covalent bonds. This gives the molecule a slight charge at each end—positive on the hydrogen side and negative on the oxygen.

This polarity makes water attract itself and other polar molecules. Think of it as molecular clinginess. This clinginess is why water is so good at dissolving things—it’s known as the 'universal solvent.' If a substance is polar, water can usually pull it apart. Salt? Gone. Sugar? See ya. Oil? Not so much.

Water naturally exists in all three states of matter—solid, liquid, and gas—without needing a fancy lab setup. Ice, liquid water, and steam are all around us, often in the same weather forecast.

Water takes its time to heat up. Its high specific heat and heat of vaporization mean it requires a lot of energy to change temperature or state. That’s why oceans stabilize the Earth’s climate and why your pool still feels like ice in May.

Cohesion and adhesion are why water climbs from plant roots to leaves and blood travels from your feet to your heart. Cohesion keeps water molecules together. Adhesion makes them stick to other surfaces—like xylem walls or blood vessels.

Surface tension is what lets bugs like water striders glide across a pond. It’s also why you can overfill a glass just a little without it spilling. It’s the trampoline of the molecular world.

Why It Matters

Water isn't just necessary for life—it's the reason life behaves the way it does. From climate regulation to cellular respiration, understanding water’s unique properties unlocks an understanding of everything from weather to biology. Every drop is a lesson in physics, chemistry, and ecology.

?

Dig Deeper

You think you know water, but you don't. It's odd. And if it wasn't so odd, you wouldn't be here. So how does this seemingly everyday substance turn out to be an epic scientific story of a strange molecule that connects you to everyone and everything on Earth – and the rest of the universe. Alok Jha explains.

Ever wonder what it is about water that makes it so important for life? In this STEMonstration, NASA astronaut Nicole Mann demonstrates the role water’s solvent properties play aboard the space station and explains what makes water so important for life as we know it.

At the heart of every cell, snack, seed, and strand of DNA are carbon-based molecules playing molecular Tetris.

Macromolecules & The Chemistry of Life

Life is built on legos—but not the kind you step on barefoot. We're talking molecular legos: the macromolecules that fuel your body, build your cells, and store your DNA’s secrets.

Scientific classification is the tool humans have used for centuries to bring order to the chaos of the natural world.

Classification: How We Make Sense of a Wild and Wonderful World

Before we can protect nature—or understand it—we have to organize it. Classification is the science of finding patterns, drawing lines, and asking: What belongs where, and why?

By observing clouds, we uncover powerful lessons about the water cycle, weather patterns, and how scientists use evidence to make predictions.

Weather Wonders: Observing Clouds and the Water Cycle

Clouds aren’t just fluffy sky art—they’re scientific clues that help us understand weather, climate, and the invisible processes shaping our planet.