So as I've been told, when a substance melts, the actual bonds of the substance aren't broken, only the IMFs (inter-molecular forces). So why is it that metal groups decrease in melting points going down when they should be increasing because more shells exist thus ions in the lattice will be larger so more IMFs therefore it takes more energy to overcome. Instead, I'm being told that since the metallic bonds get weaker due to less attraction between electron sea and the positive ion, melting point decreases.
Could someone please help me figure out what I'm missing here?