Science Common Sense

178 - Why do some substances have a higher density than others?

Imagine you have a bunch of balls of different sizes packed together in a box. The smaller balls can fit more tightly together, so more of them can fit in the box. This makes the box heavier, even if it's the same size as a box with bigger balls.

That's kind of like what happens with atoms in a substance. When the atoms are smaller and packed tightly together, the substance gets heavier and is said to have a higher density. This is why some substances, like lead, are dense and heavy, while others, like helium, are less dense and lighter.