Covalent bonding and dative bondsEdexcel International A Level Chemistry: Flashcards
What these 13 flashcards ask
- Define a covalent bond.
- What does an electron density map of a covalent molecule show?
- Why is diamond evidence for strong covalent bonding?
- How many shared pairs are in a double bond?
- How many electrons are shared in the N≡N bond?
- What is a dative covalent bond?
- What two things are needed to form a dative bond?
- How does NH₃ form NH₄⁺?
- Why are all four N–H bonds in NH₄⁺ identical?
- Why does AlCl₃ form a dimer?
- How many dative bonds are in Al₂Cl₆?
- What is the relative formula mass of Al₂Cl₆?
- How many outer electrons does each carbon atom have in HCN?
Exam questions on Covalent bonding and dative bonds
- Nitrogen atoms have atomic number 7. In nitrogen gas, N₂, two atoms are joined by a triple bond. X-ray diffraction can be used to produce an electron density map of a molecule such as N₂.Explain, in terms of electrostatic forces, how the shared electrons hold the two nitrogen nuclei together.2 marks
- Ammonia gas reacts with hydrogen chloride gas to form solid ammonium chloride, which contains the ammonium ion, NH₄⁺. In the ammonium ion all four N–H bonds are identical in length and strength. A hydrogen ion, H⁺, has no electrons.Explain why all four N–H bonds in the ammonium ion are identical even though one of them is a dative covalent bond.2 marks
- The vapour of aluminium chloride just above its sublimation temperature has a relative formula mass of 267 (Ar: Al = 27.0, Cl = 35.5). In an AlCl₃ molecule the aluminium atom has only six electrons in its outer shell.Deduce the formula of the species in the vapour and explain how it forms from AlCl₃.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).