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@ CH-103 Chemistry Tutorial 9 Answers 101) If the element with # = 114 is discovered, in which group would you expect to find it? What would be its electronic configuration and the [UPAC name? Answer : Group 14; Below Pb; [Ra] 5f46d!°7s*7p*; Ununquadium 102) How many unpaired electrons would there be in Ga"? Answer: Ground state electron configuration : [Xe] 4f'5d'6s" Ga : [Xe] 4” Total no. of unpaired electrons ac! 103a) Which metal has the lowest melting point and why? Hg (-39 °C) It has very high Ionisation Energy (IE = 1007 KJmol |). The high IE is due to (a) small size and (b) the filled d and f orbitals which are poorly shielding. The filled 4f shell in Hg increases the binding energy of outer electrons and the Ist IE of Hg is greater than that for any metal in the periodic table. The very high IE makes it difficult for the electrons to participate in metallic bonding (weak M-M bonds). The liquid has an appreciable vapor pressure at room temperature. Use: Hg vapor - (a) street lamp.: (b) in thermometers due to a large linear thermal expansion coefficient 103b) Which metal has the highest melting point and why? Name one of its uses? Tungsten, W (3380 °C) Tunsten has highest no. of valence electrons available for metallic bond formation (probably 6 per atoms, ail available and hence strong M-M bonds) Use: Filament in incandescent lamps 104) Account for the large decrease in electron affinity between lithium ad beryllium despite the increase in nuclear charge. Li = [He]2s! Be = [He]2s” In lithium, the added electron enters the 2s orbital to give Li’ ion. In beryllium, the added electron enters the 2p orbital to give Be- ion. The 2p electron in Be is much less tightly bound due to strongly shielding by the presence of 2s electrons, Hence the addition of electron in Be is endothermic and hence large decrease in EA. 
