Density is a fundamental physical property of matter that tells us how tightly packed the particles are within an object. It is a key concept introduced in middle school Science and high school Physics.
Osmium is the densest naturally occurring element on Earth, with a density of 22,590 kg/m³. It is roughly twice as dense as lead!
Density is defined as the mass of an object per unit volume.
Formula: Density (ρ) = Mass (m) / Volume (V)
(Note: The symbol for density is the Greek letter 'rho' - ρ).
To find the SI unit of density, we look at its formula:
Therefore, the SI Unit of Density is Kilogram per cubic metre (kg/m³) or kg·m⁻³.
In chemistry and daily laboratory use, a smaller unit is often used: Gram per cubic centimetre (g/cm³).
Conversion Rule: 1 g/cm³ = 1000 kg/m³ (Example: The density of pure water is 1 g/cm³, which is exactly 1000 kg/m³).
Ice floats on water because solid ice is actually *less dense* than liquid water. When water freezes, its molecules form a crystalline structure that takes up more space (volume), lowering its overall density.
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