A tornado is a wind tunel (that's probaly spelled wrong). It basically happens when wind is spinning in a circle, and it keeps picking up. This is a reason why tornados don't survive in hilly places.
Dmitri Mendeleev, he realized that the physical and chemical properties of elements were related to their atomic mass and arranged them into groups (columns)
There is a special temperature for every substance called the melting point. When a solid reaches the temperature of its melting point, it can become a liquid.
