BeCl2 has a linear shape with a bond angle of 180 degrees, where as H2O has a bent shape with a bond angle of 104.5 degrees. Explain why these molecules have different shapes despite having the same general formula of AB2.
BeCl2 contains 2 bonding pairs of electrons which arrange themselves as far away as possible to minimise the electron repulsion between them, giving a bond angle of 180 degrees and a linear shape. H2O also has 2 bonding pairs of electrons, but also 2 lone pairs of electrons on the oxygen atom. Therefore the 4 pairs of electrons spread themselves out as far as possible to minimise electron repulsion, however the repulsion between 2 lone pairs is greater than between a bonding pair and a lone pair, so the 2 lone pairs of electrons squish together the 2 bonding pairs further together, reducing the bond angle from the normal tetrahedral 109.5 degrees to 104.5 degrees , giving a bent shape.
SR
Related Chemistry A Level answers
All answers ▸A chemist synthesised two solutions A and B, they know one solution is an aldehyde and the other a ketone. Suggest how the chemist could identify which is which and describe any observations they would make
Describe how you could distinguish between ethanol, ethanoic acid, ethyl bromide and 2-methylpropan-1-ol.
Molecules of hydrogen chloride, HCl, and molecules of fluorine, F2, contain the same number of electrons. Hydrogen chloride boils at –85 °C and fluorine boils at –188 °C. Explain why there is a difference in the boiling points of HCl and F2.
Draw the mechanism for the reaction between ethanoyl chloride and a nucleophile