In the blockbuster film hit Back to the Future, which came out 30 years ago, and its sequels, this, 2015, is the future - the year Marty McFly and Doc Brown zoomed off to visit in their souped-up flying DeLorean.
Metallic bonding in magnesium. If you work through the same argument with magnesium, you end up with stronger bonds and so a higher melting point. Magnesium has the outer electronic structure 3s 2. Both of these electrons become delocalised, so the sea has twice the electron density as it does in sodium. The remaining ions also have twice the charge (if you are going to use this particular view of the metal bond) and so there will be more attraction between ions and sea.
Magnesium is a grayish-white, fairly tough metal. Magnesium is the eighth most abundant element in the earth's crust although not found in it's elemental form. It is a Group 2 element (Group IIA in older labelling schemes). Group 2 elements are called alkaline earth metals. Magnesium metal burns with a very bright light.