Which is most likely the result of millions of metal atoms crowding together so that molecular orbitals become combined?
a. the loss of metallic propertiesb. the formation of bands in a crystalc. the loss of valence electrons to other atomsd. the formation of localized valence electrons

The most likely result of millions of metal atoms crowding together so that the molecular orbitals are combined is in the formation of bands in a crystal.

When the metallic atoms crowd together there is a mutual interaction that takes place between them and they form molecular orbitals. The main force which is brings this change is the electromagnetic forces acting between atomic orbitals because of the crowding.

if you mean hydrogen and oxygen then water is the product

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.