Shapes of simple molecules and ionsAQA A-Level Chemistry: Flashcards
What these 13 flashcards ask
- What does VSEPR theory say?
- Order the repulsions
- Shape and angle of CH₄
- Shape and angle of NH₃
- Shape and angle of H₂O
- Shape of BF₃ and angle
- Shape of CO₂ or BeCl₂
- Shape and angles of PCl₅
- Shape and angle of SF₆
- Shape of XeF₄ and why
- Why is NH₃ less than 109.5°?
- How do you get the lone pairs on the central atom?
- Why is the shape of H₂O not tetrahedral?
Exam questions on Shapes of simple molecules and ions
- Boron trifluoride, BF₃, is a gas used as a catalyst in organic synthesis. It reacts with fluoride ions to form the tetrafluoroborate ion, BF₄⁻, in which boron is bonded to four fluorine atoms.Explain why BF₃ and BF₄⁻ have different shapes.2 marks
- Sulfur forms several fluorides. Sulfur hexafluoride, SF₆, is an unreactive gas used as an insulator in electrical switchgear. Sulfur tetrafluoride, SF₄, is a reactive gas used to make fluorinated organic compounds. Sulfur has six electrons in its outer shell.Deduce the number of bonding pairs and lone pairs of electrons around sulfur in SF₄ and name the shape of the molecule.2 marks
- Phosphorus forms two chlorides, PCl₃ and PCl₅. Phosphorus has five electrons in its outer shell. In the vapour phase both compounds exist as separate molecules.Deduce the shape of a PCl₃ molecule and explain why the Cl–P–Cl bond angle is about 107° rather than 109.5°.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).