group 18
A "low melting point" means that they are a gas at all temperature except at very low temperatures. Forget about the status thing, that way of thinking doesn't make any sense. All that a "high melting point" means is they are a gas only at restrictively high temperatures. If you remember, gas phase is the most "natural" phase for all matter. Intermolecular forces (and metallic bonds) are what force matter into the liquid and solid phase. So a "low melting point" refers to an element with weak interatomic forces between its atoms, and a "high melting point" means that an element has stronger interatomic forces between its atoms. Noble gasses have the weakest interatomic forces, which is why they have very very low melting points (for instance, neon has a melting point of 10 Kelvin, which is -263 Celsius)
period 5
Transition Metals differ by 18 degrees approximately.