Formula of the Compound:

The compound formed between atom X and atom Y can be determined by considering their valence electrons. Atom X has seven valence electrons, while atom Y has two valence electrons. In order to achieve stability, atoms tend to gain, lose, or share electrons to fulfill the octet rule, which states that atoms are most stable when they have eight valence electrons.

Since atom Y has only two valence electrons, it is more likely to lose these electrons rather than gain six more to achieve stability. On the other hand, atom X needs only one additional electron to complete its octet. Therefore, atom Y is likely to lose its two valence electrons to atom X, resulting in the formation of an ionic bond.

The ionic bond is formed between a metal and a non-metal where the metal atom loses electrons to become a positively charged ion (cation), and the non-metal atom gains those electrons to become a negatively charged ion (anion). In this case, atom Y, being the metal, will lose its two valence electrons to atom X, resulting in the formation of a cation Y+ and anion X-.

Type of Bond Formed:

The bond formed between atom X and atom Y is an ionic bond. Ionic bonds are characterized by the electrostatic attraction between oppositely charged ions. In this case, the cation Y+ and the anion X- will be attracted to each other due to their opposite charges.

Ionic bonds tend to be strong and have high melting and boiling points. They also typically form crystalline structures and conduct electricity when dissolved in water or in the molten state. The strength of the ionic bond depends on the magnitude of the charges on the ions and the distance between them.

Summary:

- The formula of the compound formed between atom X and atom Y is XY.
- An ionic bond is formed between them, where atom Y loses its two valence electrons to atom X, resulting in the formation of cation Y+ and anion X-.
- Ionic bonds are characterized by the electrostatic attraction between oppositely charged ions.
- Ionic compounds tend to have high melting and boiling points, form crystalline structures, and conduct electricity when in a molten or aqueous state.