This Study Mind Tutorial covers the following specification points:

Edexcel: 2.7, 2.8(i,ii), 2.9, 2.24

2.7. know that a covalent bond is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them

2.8. be able to draw dot-and-cross diagrams to show electrons in covalent substances, including:

(i) molecules with single, double and triple bonds

(ii) species exhibiting dative covalent (coordinate) bonding, including Al2Cl6 and ammonium ion

2.9. understand the relationship between bond lengths and bond strengths for covalent bonds

2.24. know that the structure of covalently bonded substances such as iodine, I₂, and ice, H₂O, is simple molecular