The bond between silicon and germanium is

Analyze the question: It asks what type of bond holds atoms together in silicon and germanium. These are the two most common semiconductor materials, so this is a semiconductor topic in Physics.

Explain the concept:

• Silicon (Si) and germanium (Ge) are both in Group 14 (IV) of the periodic table, so each has 4 valence electrons.
• To reach a stable outer shell of 8 electrons, each atom shares one electron with each of its 4 neighbours.
• Sharing of electron pairs between atoms is a covalent bond.

For the other options:

• Ionic (electrovalent): involves the transfer of electrons from a metal to a non-metal, as in NaCl. B and D mean the same thing, so neither can be the answer.
• Dative (coordinate): a covalent bond where one atom supplies both shared electrons, as in NH₄⁺. This does not happen in a pure Si or Ge crystal.

Solution:

1. Si and Ge each have 4 valence electrons.
2. Neither atom readily gives up or gains electrons, because they are similar in electronegativity.
3. They therefore share electrons, forming a covalent bond in a crystal lattice, whether Si–Si, Ge–Ge, or Si–Ge in alloys.

Answer: A. covalent

Tip: If an option pair means the same thing (here ionic and electrovalent), they cannot both be right, so you can eliminate both at once. Also remember that Group IV semiconductors (C, Si, Ge) form covalent crystals. When electrons are shared, the bond is covalent.