Most nonmetals are found at the top right of the periodic table. The exception is hydrogen, which is usually placed at the top left with the alkali metals.
Ionic bonding is a type of chemical bond that occurs when the atom of a metal definitively gives up one or more electrons to the atom of a nonmetal or hydrogen.
A covalent bond is one in which the atoms of chemical elements share their electrons in order to be stable. Covalent bonding is a type of chemical bond that occurs between hydrogen atoms and nonmetals.
With this in mind...
Lithium (Li) and Oxygen (O) - Li is a metal and Oxygen a nonmetal, so ionic bond.
Chlorine (Cl) and Fluorine (F) - Cl is a nonmetal and Fluorine is a nonmetal, so covalent bond.
Calcium (Ca) and Sulfur (S) - Calcium is a metal and Sulfur is a nonmetal, so ionic bond.
Answer: Lithium (Li) and Oxygen (O) - ionic bond.
Chlorine (Cl) and Fluorine (F) - covalent bond.
Calcium (Ca) and Sulfur (S) - ionic bond.
