For example, a very dense metal will sink to the bottom while something like wood will float on the surface. The wood is less dense compared to the water, which is why it floats. Density is the measure of how much stuff you can pack in a certain volume. The higher the density, the more stuff per volume. Think of it like packing a suitcase. If there's barely anything in there, then we can say its density is low. The more stuff crammed in the suitcase will increase the density (and therefore the weight), while keeping the volume the same.
The electrical charge of particles. The total number of electrons in an atom is always the same as the number of protons in the nucleus. This means atoms have no overall electric charge. The number of protons in an atom is called its atomic hater number.
