By Anthony Ellison
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Within the Bhopal catastrophe of 1984, nearly 2,000 citizens dwelling close to a chemical plant have been killed and 20,000 extra suffered irreversible harm to their eyes and lungs following the unintentional unencumber of methyl isocyanate. This tragedy served to concentration overseas realization at the desire for governments to spot unsafe ingredients and help neighborhood groups in making plans how one can care for emergency exposures.
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Extra info for AS Chemistry (Instant Revision)
There are two categories: ● van der Waals’ forces; ● hydrogen bonds. 32 S TRUCTURE AND B ONDING (7) van der Waals’ forces Induced-dipole/induced-dipole forces Induced-dipole/induced-dipole forces, also called temporary dipole/temporary dipole forces, are weak attractive forces that exist between all molecules. They arise when an instantaneous imbalance in the electron distribution in a molecule induces a corresponding imbalance in neighbouring molecules, leading to a weak electrostatic attraction.
50 T HE P ERIODIC TABLE (7) Group 7 The elements in group 7 comprise the halogens. Some information about the halogens chlorine to iodine is given in the table below. 215 Chlorine (Cl2) turns damp blue litmus paper red, then bleaches it. Cl2(g) + H2O(l) HCl(aq) + HClO(aq) chloric (I) acid Bromine (Br2) displaces iodine from a solution of potassium iodide and, as a consequence, the iodine turns starch blue-black. ) Br2(aq) + 2I–(aq) I2(aq) + 2Br–(aq) Iodine (I2) turns starch solution from colourless to blue-black.
This difference is explained by the additional presence of permanent-dipole/permanent-dipole forces between propanone molecules. H3 C C δ+ O H3 C CH3 δ– C δ+ CH3 O δ– 33 S TRUCTURE AND B ONDING (8) Hydrogen bonding The hydrogen bond is the strongest intermolecular force, typically about 1/10th the strength of a covalent bond. A hydrogen bond is a weak directional bond formed between a δ+ hydrogen atom in one molecule and the lone pair of electrons on a highly electronegative atom in another molecule.