$$\( X\)$$ and $$\(Y\)$$ are elements in Period 3 of the Periodic Table. What could be the formula of a compound formed between elements $$\(X\)$$ and $$\(Y\)$$ ?

9.2.1 describe, and write equations for, the reactions of the elements with oxygen

9.2.2 state and explain the variation in the oxidation number of the oxides

9.2.3 describe, and write equations for, the reactions, if any, of the oxides with water including the likely pHs of the solutions obtained

9.2.4 describe, explain and write equations for, the acid / base behaviour of the oxides , MgO, and including, where relevant, amphoteric behaviour in reactions with acids and bases (sodium hydroxide only)

9.2.5 describe, explain, and write equations for, the reactions of the chlorides NaCl, with water including the likely pHs of the solutions obtained

9.2.6 explain the variations and trends in 9.2.2, 9.2.3, 9.2.4 and 9.2.5 in terms of bonding and electronegativity

9.2.7 suggest the types of chemical bonding present in the chlorides and oxides from observations of their chemical and physical properties