The period is the end of the sentence!!!
Answer:
It is a pure substance. Magnesium is an element.
The sideways and downward movement of the edge of a plate of the earths crust into the mantle beneath another plate
Hydrogen bonding occurs between a hydrogen atom and an electronegative atom (e.g., oxygen, fluorine, chlorine). The bond is weaker than an ionic bond or a covalent bond, but stronger than van der Waals forces (5 to 30 kJ/mol). A hydrogen bond is classified as a type of weak chemical bond.
