How hard it is for carbon to form an ionic compound would have been answerable if at all carbon can form an ionic compound. Carbon molecules cannot form an ionic compound. This is due to the fact that carbon has four valence electrons, which will not make it be able to form an ionic compound. For an ionic reaction to take place, there must be a transferring of the electron. And for an element to transfer electron, it should have like one, two, or three valence electrons to receive, and five, six, or seven electrons to donate.
If it has four electrons, the element already has a complete valence electron. Hence, it cannot transfer or receive any extra electron. However, an element with four valence electrons can share its electrons. This is called a covalence reaction. Therefore, a carbon molecule can share its electrons to form a covalent compound. Carbon finds it easy to form a covalent compound, but almost impossible to form an ionic compound.