1.3 bonding- shapes Flashcards
properties of linear molecules
-bonding pairs: 2
-lone electron pairs: 0
-bond angle: 180
-example: beryllium chloride
properties of v-shaped molecules
-bonding pairs: 2
-lone electron pairs: 2 or 1
-bond angle: 104.5 or a little less than 120
-example: water
properties of trigonal planar molecules
-bonding pairs: 3
-lone electron pairs: 0
-bond angle: 120
-example: boron trifluoride
properties of pyramidal molecules
-bonding pairs: 3
-lone electron pairs: 1
-bond angle: 107
-example: ammonia
properties of tetrahedral molecules
-bonding pairs: 4
-lone electron pairs: 0
-bond angle: 109.5
-example: methane
properties of trigonal bipyramidal molecules
-bonding pairs: 5
-lone electron pairs: 0
-bond angle: 90 and 120
-example: phosphorus pentachloride
properties of square planar molecules
-bonding pairs: 4
-lone electron pairs: 2
-bond angle: 90
-example: xenon tetrafluoride
properties of seesaw molecules
-bonding pairs: 4
-lone electron pairs: 1
-bond angle: 89 and 119
-example: sulfur tetrafluoride
properties of t-shaped molecules (trigonal bipyramidal with lone pairs)
-bonding pairs: 3
-lone electron pairs: 2
-bond angle: 88 (when lone pairs are next to each other) or 120 (when lone pairs are on opposite sides)
-example: chlorine trifluoride
what is the electron pair repulsion theory (3)
-valence electron pair predicts shape and bond angles of molecules
-Electrons are negatively charged and will repel other electrons
-bonding pair of electrons will repel other electrons, forcing the molecule to adopt a shape where repulsion is minimised
explain how electron pair repulsion theory can be used to predict the shape and bond angle of PF3 (phosphorus trifluoride) (6 marks)
-P has 5 electrons in outer shell
-P gains 3 electrons from F to gain full outer shell
-there are 3 bonding pairs and 1 lone pair
-electron pairs repel as far as possible
-lone pairs repel more
-tetrahedral shape, bond angle=109.5
