Why generally metals are good conductor and non metals are bad conductor of electricity

Metals - The close packing of the metal ions in the lattice and the delocalised electrons ensure it can carry kinetic energy through the lattice.

Non - metals have fewer free electrons and electrons are held tightly, meaning they're not allowed to move freely.

asthenosphere and convection

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.