Draw the structures of the following molecules: (i) XeF2 (ii) H2S2O8

(i) XeF2:

Xenon (Xe) is a noble gas with 8 valence electrons. In XeF2, two fluorine atoms each share one electron with xenon, forming two covalent bonds. Xenon uses two of its valence electrons for bonding, leaving six electrons as three lone pairs. The resulting structure is linear, with the xenon atom in the center and the two fluorine atoms on either side.

   F-Xe-F

The three lone pairs are arranged such that they minimize repulsions, leading to the linear geometry. The electron-pair geometry is trigonal bipyramidal (five electron pairs), but the molecular geometry is linear (2 bond pairs, 3 lone pairs).

(ii) H2S2O8 (Peroxodisulfuric acid):

This molecule contains two sulfur atoms, each bonded to two oxygen atoms and one hydroxyl group. These sulfur atoms are also connected by a peroxide linkage (-O-O-). Each sulfur atom has an oxidation state of +7. The structure can be represented as:

     O     O
     ||     ||
HO-S-O-O-S-OH
     O     O

Each sulfur atom is bonded to four oxygen atoms in a tetrahedral arrangement. The peroxide linkage is located between two of the sulfur atoms. The molecule possesses a symmetric structure.

The Lewis structures are essential for visualizing the electronic arrangement and bonding interactions within these molecules. The linear structure of XeF2 and the tetrahedral arrangement around each sulfur atom in H2S2O8 are crucial in understanding their molecular geometries and properties.