Question

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one:

1. Forms an anion
2. Forms a cation
3. Has four electrons in its valence shell?

Answer 1

The electronic configuration of:

X (6) = 2, 4

Y (9) = 2, 7

Z (12) = 2, 8, 2

1.  Y forms an anion as it needs just one more electron to complete its octet.
2. Z forms a cation. It will lose its 2 electrons to achieve a stable electronic configuration, thus forming a cation.
3. An ionic bond is formed between Y and Z and its molecular formula is ZY₂.