AS Chemistry Shapes of Molecules PDF
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2024
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Summary
This is a document about molecular shapes in chemistry. It describes different shapes of molecules, including linear, trigonal planar, tetrahedral, etc. and includes examples of various molecules with their corresponding shapes. The document also discusses VSEPR theory and provides hints and tricks for deducing molecular shapes.
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AS CHEMISTRY 3.1.3 BONDING SHAPES OF MOLECULES 3D SHAPE BP’s / LP’s BOND ANGLE EXAMPLES STRUCTURE LINEAR 2 BP / 0 LP 180O...
AS CHEMISTRY 3.1.3 BONDING SHAPES OF MOLECULES 3D SHAPE BP’s / LP’s BOND ANGLE EXAMPLES STRUCTURE LINEAR 2 BP / 0 LP 180O BeCl2, CO2 (PLANAR) TRIGONAL 3 BP / 0 LP 120O BF3, AlCl3 PLANAR TETRAHEDRAL 4 BP / 0 LP 109.5O CH4 TRIGONAL 5 BP / 0 LP 120O & 90O PCl5 BIPYRAMIDAL OCTAHEDRAL 6 BP / 0 LP 90O SF6 3D SHAPE BP’s / LP’s BOND ANGLE EXAMPLES STRUCTURE V-SHAPED / 2 BP / 1,2, or 3 BENT 107O H2O, SO2 LP (PLANAR) TRIGONAL 3 BP / 1 LP 104.5O NH3, PCl3 PYRAMIDAL SQUARE 4 BP / 2 LP 90O XeF4 PLANAR AQA www.chemistrycoach.co.uk © scidekick ltd 2024 AS CHEMISTRY 3.1.3 BONDING V.S.E.P.R. VALENCE The “valence shell” refers to the outermost energy level containing SHELL electrons. Only electrons in the valence shell are involved in bonding. ELECTRON Electrons exist in pairs in the valence shell. They can exist as bonding PAIR pairs or lone pairs. REPULSION All electrons have a negative charge, so it stands to reason that they repel each other. The is what dictates how the bonds arrange themselves around the central atom. HINT | TIPS | HACKS When deducing the shape of a molecule, start by finding the “central” atom. What group is it in? This tells you how many valence electrons it has. Lone Pair to Bonding pair repulsion is greater than Bonding Pair to Bonding Pair repulsion. That is why lone pairs distort the shape of the molecule. If a molecule has a double bond, treat this the same as a single bond when it comes to VSEPR. If a molecule has a charge, it does not affect the shape of the molecule. If a molecule has a charge, it was brought to the molecule by one of the “satellite” atoms that bonded to the central atom, usually using a coordinate bond. e.g. NH4+, is tetrahedral. It is formed by the addition of a H+ ion top NH3. The N provides the lone pair to form a coordinate bond with the H+ ion. How To Deduce the Shapes of Molecules AQA www.chemistrycoach.co.uk © scidekick ltd 2024
