Final answer:
Element X from group 2 loses electrons to element Y from group 17, forming an ionic bond and resulting in the creation of an ionic compound with a ratio of one X2+ to two Y- ions.
Step-by-step explanation:
When a compound is formed between element X from group 2 and element Y from group 17, X loses electrons to Y to form an ionic bond. This means that the correct answer is 1) X loses electrons to Y to form an ionic bond.
Elements of group 2, such as calcium, have two electrons in their outer shell which they readily lose to achieve a stable electron configuration. When they react with elements from group 17, like chlorine, which need to gain one electron to fill their outer shell, each atom of element X will lose two electrons, and two atoms of element Y will each gain one of these electrons. This transfer of electrons leads to the formation of cations (X2+) and anions (Y−), resulting in the creation of an ionic compound like CaCl2, with a ratio of one Ca2+ to two Cl− ions.