一、碱金属的单质1.钠与水反应时钠浮在水面上,能不能说明钠比水密度小?钠熔化成小球,能不能说明钠熔点低?答就像重的物体比轻的物体下落快一样,我们有一个根深蒂固的观念,浮在水面上的物体比水密度小。实际上并非如此。钢铁比水密度大,但用钢铁做成的轮船却可以漂在水面上;石头比水密度大,但石头也可以在水上“打水漂”而不沉。只有当物体是实心的、静止的 1. Elemental Alkaline Metal 1. When sodium reacts with water, sodium floats on the surface of the water. Can it be shown that the density of sodium is lower than that of water? Sodium is melted into pellets, can you tell if sodium has a low melting point? A is like a heavy object. As objects fall faster, we have a deeply ingrained idea that objects that float on water are less dense than water. This is not actually the case. Steel is denser than water, but ships made of steel can float on the water; stones are denser than water, but stones can also “float” on the water without sinking. Only when the object is solid and stationary