Note that there are now several types of treatments and medical providers for which Medicare Part B pays 100% of the approved charges rather than the usual 80%. These categories of care include home health care, clinical laboratory services, and flu and pneumonia vaccines.
A giant covalent structure is a three dimensional structure of atoms held together (obviously) by Covalent bonds. These atoms are often all the same-so the elements Silicon and Carbon in the allotropes Diamond and Graphite are Giant Covalent structures.
Silicon forms giant covalent molecules in which each Si atom is covalently bonded to 4 other. Si atoms. Covalent bonds are strong (comparable to metallic bonds) and as each Si atom. forms 4 of them all 4 bonds must be broken to separate the atoms and Si has a very high b.p.,