Both H2 and C2H4 contain molecules in which the entire molecule contains 4 atoms (in the case of H2), or 6 atoms (in the case of C2H4). However, these molecules contain molecules in which the atoms are bonded to each other in different ways. In the case of H2, molecules are bonded to each other in the following way:
In this case, the molecules themselves are circles. The geometry configurations of H2 are shown as below where the big blue circle with the three smaller red circles represents the molecule, while the smaller blue circle with three smaller red circles represents its geometry. Note that the molecule is not symmetric about at the center, so the molecules themselves are not rectangles.
When we start to talk about metals, you will see that they are similar to the giant covalent compounds in that they are formed by getting covalent bonds between their parts. But they are very different because they are formed by 100 or more electrons rather than by 4. When a metal is heated, the electrons get excited and rush off like a cloud to become free particles and the metal becomes positively charged. It is called a plasma state and the metal is an ion.
Crystals are never simple. They are complicated. That is because they are formed by attracting the atoms in a lattice. But there are always defects in crystals which account for the imperfections in the structure. A common defect is a vacancy. If you unzip a zipper, you see a lot of gaps. But we know that a zipper is made from 2 orifices that stick together. One pops out in order to make the zipper. d2c66b5586