Q. The table shows information about the halogens in Group 7 of the periodic table. Name of halogen Melting point in C Boiling point in C Electronic structure Fluorine 220 88... Chlorine 0 35 2,8,7 Bromine 7 +58 2,8,8,7 Iodine +4 +83 2,8,8,8,7 (a) Use information from the table to help you to answer these questions. (i) Name one halogen that is a solid at 25 C.... () Name one halogen that is a gas at 25 C. (iii) (iv)... Use the periodic table on the Data Sheet to help you to work out the correct electronic structure for fluorine. Write your answer in the table above. Use the periodic table on the Data Sheet to name one Group 7 element that is not shown in the table above.... () () () (b) A teacher demonstrated the reactivity of the halogens to some students. Halogen vapour was passed over heated iron wool in a fume cupboard. Page of 8
The teacher s observations are shown in the table below. Observations During the reaction After the reaction Bromine The iron wool glowed A red brown solid had been produced Chlorine The iron wool glowed brightly A dark brown solid had been produced Iodine The iron wool did not glow A black solid had been produced (i) What is the order of reactivity of these three halogens? Order of reactivity: most reactive halogen... 2... least reactive halogen 3... () Explain how you used the teacher s observations to decide your order of reactivity............. (2) (Total 7 marks) Q2. A teacher demonstrated the reactivity of the halogens to some students. Halogen vapour was passed over heated iron wool in a fume cupboard. Page 2 of 8
The teacher s observations are shown in the table below. Observations During the reaction After the reaction Bromine The iron wool glowed A red brown solid had been produced Chlorine The iron wool glowed A dark brown solid had been produced Iodine The iron wool did not glow A black solid had been produced (a) From these observations what conclusion can be made about the order of reactivity of the three halogens? Explain your conclusion. (2) (b) In terms of electronic structures, explain why iodine is less reactive than bromine. (3) (Total 5 marks) Q3. Fluorine is more reactive than chlorine. Fluorine reacts with most elements in the Periodic Table. However, fluorine does not react with argon. Atomic numbers: F 9; Cl 7; Ar 8. (a) To which group of the Periodic Table do fluorine and chlorine belong?... () (b) (i) Give one use for argon. () Page 3 of 8
Explain why the noble gas argon is unreactive. (2) (c) (i) Give one use for chlorine. () Draw the electron arrangement of a chlorine atom. (2) (iii) Explain why fluorine is more reactive than chlorine. (3) (Total 0 marks) Page 4 of 8
M. (a) (i) iodine fluorine or chlorine (iii) 2,7 (iv) astatine (b) (i) chlorine>bromine>iodine any two suitable comparisons about the extent to which the iron wool glowed eg chlorine is more reactive than bromine because iron glowed more brightly with chlorine than bromine () eg bromine is more reactive than iodine because iron glowed with bromine but not with iodine () 2 [7] M2. (a) the conclusion is that chlorine and bromine are more reactive than iodine any suitable comparisons about the extent to which the iron wool glowed eg because iron glowed with chlorine and bromine but did not glow with iodine (b) iodine is less reactive than bromine because the iodine (atom) is bigger or outer electrons (level / shell) further from the nucleus accept converse for bromine therefore the forces attracting an incoming electron are weaker or there is more shielding of the forces attracting an incoming electron therefore the outer electron gained less easily Max 2 if no mention of outer energy level / shell or of outer electron (s) [5] Page 5 of 8
M3. (a) group seven/7vii accept halogens (b) (i) in light bulbs/lasers accept any other specified use as an inert atmosphere e.g. (argon) welding, storing explosives, fluorescent lights 2.8.8/has a full/8 in/outer shell electrons accept does not need to share/gain/lose electrons (c) (i) any one from: disinfectant bleaching agent sterilising water/kills bacteria manufacture of HCl water treatment not: cleaning/in pools purification of water kills germs warfare antiseptic inner shells 2,8 outer shell 7 (iii) fluorine: accept the converse reasons for chlorine gains one/an electron easier/is more strongly attracted not more strongly held Page 6 of 8
less shielding of nucleus by inner electron shells less distance from (attraction of) nucleus/less shells [0] Page 7 of 8
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