Q. In 869, a scientist put the 60 known elements into his periodic table. Photograph RIA NOVOSTI/ SCIENCE PHOTO LIBRARY Draw a ring around the correct answer to complete each sentence. Boyle. (a) The scientist who put these elements into a periodic table was Mendeleev. Newlands. () (b) First he put the 60 known elements in order of their atomic weight. boiling point. electrical conductivity. () (c) Then he put elements with similar chemical properties in columns, known as groups. periods. rows. () (d) His periodic table had gaps for elements that were uncommon. undiscovered. unreactive. () Page of 28
(e) From 900 onwards, the modern periodic table was produced. The modern periodic table is an arrangement of elements in terms of electronic structures. their neutron numbers. atomic weights. () (Total 5 marks) Q2. Sodium is in Group of the periodic table. (a) Here are some statements about sodium. Which two of these statements are correct? Tick ( ) two boxes. Statement Tick ( ) Sodium is a metal. Sodium is a halogen. Sodium forms an ion with a + charge. Sodium forms covalent compounds. (2) (b) Sodium reacts with water. A student drew this diagram and wrote the observations A, B, C and D about the reaction between sodium and water. A B C D The sodium floated and started giving off a gas. The sodium melted. The piece of sodium became smaller until all the sodium had gone. A colourless solution was left. Page 2 of 28
Use these observations to answer parts (i) and. (i) Which observation, A, B, C or D, shows that sodium has a low density? () (iii) Which observation A, B, C or D, shows that the reaction is exothermic? What is the name of the gas given off in this reaction?... () () (Total 5 marks) Q3. 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.... () () () Page 3 of 28
(b) A teacher demonstrated the reactivity of the halogens to some students. Halogen vapour was passed over heated iron wool in a fume cupboard. 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) Page 4 of 28
Q4. A teacher demonstrated the reactivity of the halogens to some students. Halogen vapour was passed over heated iron wool in a fume cupboard. 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) Page 5 of 28
(b) In terms of electronic structures, explain why iodine is less reactive than bromine. (3) (Total 5 marks) Q5. The periodic table was developed over about 200 years. In 869, a Russian scientist, Dimitri Mendeleev, arranged the 60 known elements into his periodic table. Mendeleev put the elements in order of their increasing atomic weights. Then he put elements with similar chemical properties in the same columns. He left gaps in his periodic table. The modern periodic table on the Data Sheet may help you to answer these questions. (a) Mendeleev s periodic table was produced without any knowledge of the atomic structure of elements. State why Mendeleev left gaps in his periodic table. () Page 6 of 28
(b) The modern periodic table was produced with knowledge of the atomic structure of elements. The modern periodic table is an arrangement of the elements in terms of their atomic structures. Explain how. (3) (Total 4 marks) Q6. The periodic table on the Data Sheet may help you to answer some of these questions. (a) Draw a ring around the correct answer to complete these sentences. (i) compounds. Dimitri Mendeleev attempted to classify elements. mixtures. () atomic weight. He arranged them in order of their boiling point. electrical conductivity. () (iii) atomic (proton) number. They are now arranged in order of their atomic weight. mass number. () Page 7 of 28
(b) In the periodic table between Groups 2 and 3 there is a block of metals which includes chromium, iron and nickel. (i) Which one of the following is the correct name for this block of metals? Draw a ring around the correct answer. alkali metals reactive metals transition metals () The properties of iron and those of the Group metal sodium are different. Put a tick ( sentence. ) next to the two correct phrases which could complete the following Compared to sodium, iron ( ) has a higher melting point. has a lower density. is harder. is more reactive. is weaker. (2) (Total 6 marks) Page 8 of 28
Q7. Read the information about the development of the periodic table and answer the questions that follow: The modern periodic table on the Data Sheet may help you to answer these questions. (a) Döbereiner suggested that calcium (Ca), strontium (Sr) and barium (Ba) were also a triad. Use relative atomic masses to explain why............. () (b) Suggest why Döbereiner s ideas were replaced by those of Mendeleev....... () (c) Lithium, sodium and potassium are in Group. All these elements react with water. Describe what you see when potassium is added to water.......... (2) Page 9 of 28
(d) In terms of electronic structure, explain why: (i) elements in the same group of the periodic table have similar chemical properties () transition elements have similar properties even though they are not in the same group (2) (iii) in Group, lithium is less reactive than potassium. (2) (Total 9 marks) Q8. The periodic table on the Data Sheet may help you to answer these questions. Draw a ring around the correct answer to complete these sentences. (a) The Russian chemist who introduced his periodic table in 869 was Brønsted. Lowry. Mendeleev. () (b) He put elements with similar chemical reactions in columns, known as groups. periods. rows. () Page 0 of 28
(c) He left gaps for elements that were insoluble. unreactive. undiscovered. () (d) He did not put water, H 2 O, into the periodic table because water is a compound. liquid. mixture. () (Total 4 marks) Q9. Chlorine and bromine are important Group 7 elements. (a) Explain why chlorine is added to drinking water....... () (b) Describe what you would see when bromine water is added to an unsaturated organic compound....... () (c) Bromine can be extracted from seawater. The dissolved bromide ions are reacted with chlorine. Bromine and chloride ions are formed. (i) Complete and balance the equation below, which represents the reaction between chlorine and bromide ions. Cl 2 + 2Br... +... () Describe what you see when chlorine is added to a solution containing bromide ions. () Page of 28
(d) In terms of electronic structure: (i) state why bromine and chlorine are both in Group 7 () explain why bromine is less reactive than chlorine. (3) (e) What is the result of adding acidified silver nitrate solution to a solution containing: (i) chloride ions () bromide ions? () (Total 0 marks) Page 2 of 28
Q0. (a) The periodic table on the Data Sheet may help you to answer this question. Part of the periodic table is shown below. Choose your answers only from the letters shown in the periodic table above. Which letter, A to E, represents: (i) sodium Letter... () a non-metal Letter... () (iii) a Group 2 element Letter... () (iv) a transition element? Letter... () (b) Complete these sentences by drawing a ring around the correct answer. (i) Attempts to classify the elements into a periodic table were made Arrhenius and Dalton by Brønsted and Lowry Mendeleev and Newlands () Page 3 of 28
They arranged the elements in order of their atomic weight melting point reactivity () (iii) They put elements in the same Group if they had similar boiling points chemical reactions electrical conductivities () (iv) We now know that elements in the same Group have the same number of electrons neutrons in their outer shell (energy level). protons () (Total 8 marks) Page 4 of 28
Q. Read the information about the periodic table. Portrait of Dimitri Mendeleev by Ilya Repin When the Russian chemist Dimitri Mendeleev put forward his periodic table in 869, the atomic structure of elements was unknown. Mendeleev tried to arrange the elements in a meaningful way based on their chemical reactions. First he put the elements in order of their increasing atomic weight. He then put elements with similar properties in the same column. However, he left gaps, and sometimes did not follow the order of increasing atomic weight for example, he placed iodine (atomic weight 27) after tellurium (atomic weight 28). Within a few years there was sufficient evidence to prove that Mendeleev was correct. Our modern periodic table has evolved from Mendeleev s table. The modern periodic table on the Data Sheet may help you to answer these questions. (a) (i) State why Mendeleev left gaps. () State why some elements were not placed in order of increasing atomic weight. () Page 5 of 28
(b) (i) The periodic table is now based on atomic structure. Explain how. (3) Suggest why it is impossible to have an undiscovered element that would fit between sodium and magnesium. () (c) Explain, in terms of electrons, why fluorine is the most reactive element in Group 7...................... (3) (Total 9 marks) Page 6 of 28
M. (a) Mendeleev (b) atomic weight (c) groups (d) undiscovered (e) electronic structures [5] M2. (a) sodium is a metal sodium forms ions with a + charge (b) (i) A B (iii) hydrogen [5] M3. (a) (i) iodine fluorine or chlorine (iii) 2,7 (iv) astatine (b) (i) chlorine>bromine>iodine Page 7 of 28
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] M4. (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] M5. (a) for undiscovered elements Page 8 of 28
(b) because the elements are in order of number of electrons or proton number because the number of energy levels / shells is the number of the period because the number of electrons in the outer energy level / shell is the number of the group, except in the case of the noble gases [4] M6. (a) (i) elements (iii) atomic weight atomic (proton) number (b) (i) transition metals has a higher melting point is harder 2 [6] M7. (a) 40 (Ca) + 37 (Ba) 2 = 88.5 accept a recognition that the average is near 88 or it is the average of the other two accept Sr is midway between Ca and Ba (b) eg newly discovered elements / atoms didn t fit (into triads) or didn t apply to all elements / atoms or lot of exceptions he = Döbereiner ignore Mendeleev left spaces or not enough evidence Page 9 of 28
(c) any two from: fizzes / bubbles / gas hydrogen alone is insufficient ignore incorrect name if gas stated violent / vigorous / explodes / very fast reaction accept container explodes ignore strong reaction floats / on surface ignore sinks moves (very quickly) melts (into a ball) bursts into flame accept (bright) light ignore colour / glow gets smaller / (reacts to) form a solution / dissolves / disappears etc steam / gets hot (owtte) ignore alkaline solutions or change in colour etc (d) (i) same number of electrons in outer shell accept energy level for shell accept a correct reference to a specific group eg (all) have one electron in outershell / (all) lose one electron (when they react) 2 electrons fill an inner / 3 rd shell accept energy level for shell accept d-level being filled accept specific reference to 3rd shell accept descriptions in terms of 3d & 4s etc (usually) same number of outer / 4 th shell electrons Page 20 of 28
(iii) it = lithium accept energy level for shell or converse reasoning for potassium outer shell electron closer to nucleus accept fewer shells / smaller atom more (electrostatic) attraction (to nucleus) / electrons less likely to be lost accept less shielding / isn t much shielding ignore nucleus has more influence but accept nucleus has more influence over the outer electron(s) do not accept magnetic / gravitational attraction [9] M8. (a) Mendeleev (b) groups (c) undiscovered (d) compound [4] M9. (a) kills bacteria / sterilises (water) allow kills microorganisms / microbes / germs allow makes (water) safe (to drink) or disinfectant ignore cleans water or removes impurities / bacteria (b) goes colourless / decolourised (from red / red-brown / brown / yellow / orange) allow colour disappears ignore goes clear or discoloured do not accept incorrect initial colour do not accept precipitate (c) (i) Br 2 and 2Cl allow multiples / fractions if whole equation balanced Page 2 of 28
changes to red / red-brown / brown / yellow / orange do not accept effervescence / fizzing / precipitate / gas given off ignore vapour / temperature changes / ignore initial colour (d) (i) 7 outer electrons or same number of outer electrons allow last / final shell for outer allow energy level / orbit / ring for shell allow need to gain e to have a full outer shell ignore similar number of outer electrons bromine / it (atom) is bigger or must be a comparison outer electrons (level / shell) further from nucleus or more shells do not accept more outer shells ignore more electrons forces / attractions are weaker or more shielding or attracts less do not accept magnetic / gravitational / intermolecular forces allow electron(s) attracted less easily electron(s) gained less easily outer / last / final must be mentioned once, otherwise max 2 marks. accept converse for chlorine throughout where clearly stated 3 (e) (i) white precipitate or white solid ignore names of chemicals cream precipitate or cream solid allow pale yellow / off-white precipitate / solid ignore names of chemicals [0] M0. (a) (i) B (iii) (iv) A E D Page 22 of 28
(b) (i) Mendeleev and Newlands atomic weight (iii) chemical reactions (iv) electrons [8] M. (a) (i) undiscovered elements owtte they would be in the wrong group / have the wrong / different properties / don t fit the pattern owtte allow atomic weights may have been wrong (b) (i) any three from: elements arranged in proton / atomic number order ignore mass number / atomic weight / neutrons throughout group: elements in the same group / column have same number of outer electrons owtte group: number of shells increase down group period: elements in the same period / row have the same number of shells / energy levels period: number of protons / electrons increase across period atomic number: link of atomic number to number of protons atomic number gives number of electrons 3 it would mean splitting a proton / electron or implication of splitting proton / electron Page 23 of 28
(c) must be a comparison (outer) electron closer (to nucleus) accept fewer (electron) shells / energy levels fluorine is the smaller/est stronger/est attraction (to nucleus) owtte do not allow magnetic / intermolecular forces or less screening (by inner electrons) electron gained more easily need some indication of outer electron shell somewhere in explanation otherwise max of 2 marks [9] Page 24 of 28
E7. In part (a) most candidates were able to explain why calcium, strontium and barium were a triad. Common incorrect responses were based on atomic number or similarity of chemical reactions. Far too many candidates in part (b) focused on Mendeleev and wrote about him leaving spaces for new elements. In part (c) This part was answered very well. A few named the products rather than described what is seen. Part (d)(i) was well answered by most candidates. The common error was to omit a reference to the outer shell of electrons. In part (d) this was the second poorest attempted question on the paper. There was little appreciation that transition elements (generally) have the same number of outer shell electrons or that an inner shell was being filled. Many candidates had vague ideas about overlapping shells and stated a variety of numbers of electrons in the outer shell even suggesting it was full. Other candidates based their explanations on physical properties, particularly conductivity and delocalised electrons. The term orbital has a specific meaning in chemistry and is not equivalent to shell, orbit or energy level. A majority of candidates in part (d)(iii) were able to gain credit for explaining why lithium is less reactive than potassium, although many preferred to explain why potassium is more reactive than lithium! In a question such as this, a comparison is required so it is essential to include comparative terms such as more, closer, stronger or easier. Simply saying easy, close or strong is insufficient. Candidates should be careful not to say that lithium has fewer outer shells when they mean fewer shells. A significant minority of candidates still persist in writing about magnetic, gravitational or bonding attractions, and did not gain the second marking point. E8. Generally, this question was well attempted. Part (d) proved to be difficult for many candidates. E9. Parts (a) and (d) were answered quite well, the other parts less so. (a) (b) Most candidates knew why chlorine is added to drinking water. However, candidates need to say that chlorine kills bacteria rather than just removes bacteria. Weaker candidates simply stated it was to clean the water or thought it softened the water. Less than half of the candidates knew that bromine water was decolourised. It does not go clear and neither does it become discoloured. (c) (i) Only the best candidates were able to complete and balance the equation. Most candidates had no idea what the products of the reaction were, and charges were frequently omitted/added even when the products formulae were correct. The large majority of the candidates were unable to describe the effect of chlorine on bromide ions. Many candidates thought that a precipitate formed or that there was an effervescence. Page 25 of 28
(d) (i) The majority of candidates knew that these elements have the same number of outer electrons (7) or need one electron to gain a complete outer shell of electrons. Chlorine and bromine do not have a similar number of outer electrons. An excellent discriminator as usual, and some excellent answers were seen. In a question such as this, a comparison is required so it is essential to include comparative terms such as more/most, closer/closest, stronger/strongest or easier/easiest. Simply saying easy/easily, close or strong/strongly is insufficient. Candidates needed to mention outer electron or outer energy level or outer shell somewhere in their answer to receive full credit. Some candidates suggested that a bromine atom loses an electron less easily. Others wrote about bromine having more outer shells than chlorine. Some candidates thought that intermolecular, magnetic or gravitational forces hold the electrons to the nucleus, while others referred to the strength of the bond between electron and nucleus. The third marking point proved elusive for many who often concluded their answer with the words therefore bromine is less reactive rather than therefore bromine gains an electron less easily. (e) A quite discriminating question. (i) Less than half the candidates knew that a white precipitate/solid was formed when silver nitrate solution was added to a solution containing chloride ions. Simply saying that the solution goes white or milky is insufficient. Even fewer candidates knew that a pale yellow (or cream) precipitate was formed with bromide ions. Candidates should be aware that a yellow precipitate is formed when silver nitrate solution is added to a solution containing iodide ions. E0. Generally this question was quite well answered. Part (b)(i) and (b)(iii) were least well answered although the majority of candidates gained the marks. E. Part (a)(i) was well answered by all but the weakest candidates. Part (a) was well done by most candidates but some confused physical and chemical properties, or simply said they were placed in proton number order without comment. In (b)(i) most candidates linked group number to the number of outer electrons and many also linked the periods to the number of energy levels (shells) or stated that the table was arranged in increasing atomic (proton) number order. However, many seemed not to realise that three marks required three pieces of information. Elements in the same group do not have the same number of outer shells and neither do they have the same number of atoms in the outer shell. Many candidates were careless in the use of language and referred to moving along a group and moving down a period. Others referred to placing the elements in order of increasing atomic mass. In part (b) 40% of the candidates correctly reasoned that it would mean splitting a proton or an electron. The popular incorrect response was that gaps hadn t been left or that there is no space for another element. Page 26 of 28
There were some excellent answers were seen from the more able candidates in part (c). As usual in a question such as this, a comparison is required so it is essential to include comparative terms such as more/most, closer/closest, stronger/strongest or easier/easiest. Simply saying easy, close or strong is insufficient. Candidates needed to mention outer electron/outer energy level somewhere in their answer to receive full credit. Some candidates thought the important factor was that fluorine only needed to gain one electron, while other candidates thought fluorine lost an electron and suggested group 7 elements became more reactive down the group. Other candidates thought that intermolecular/magnetic/gravitational forces held the electrons to the nucleus. Page 27 of 28
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