Learn Extracted exam questions IGCSE Chemistry 0620 Chemistry June 2025 Question Paper 43
0620 Chemistry June 2025 Question Paper 43
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1 A list of substances is shown. aluminium oxide calcium oxide chlorine ethanol graphite nitrogen oxygen propane propene silicon(IV) oxide
Answer the questions using the list of substances.
Each substance may be used once, more than once, or not at all.
State which of the substances:
(a) is a compound with a giant covalent structure [1]
(b) is an unsaturated hydrocarbon [1]
(c) is an amphoteric oxide [1]
(d) is a good conductor of electricity when solid [1]
(e) contains simple molecules with 9 atoms [1]
(f) react together to form slag in the blast furnace and [2]
(g) belongs to a homologous series whose general formula is CnH2n+2 [1]
(h) is manufactured by the catalytic addition of steam to ethene [1]
(i) is a gas that is approximately 78% of clean, dry air [1]
[Total: 10] , ,
(a) is a compound with a giant covalent structure ............................................................................................................................................. [1]
(b) is an unsaturated hydrocarbon ............................................................................................................................................. [1]
(c) is an amphoteric oxide ............................................................................................................................................. [1]
(d) is a good conductor of electricity when solid ............................................................................................................................................. [1]
(e) contains simple molecules with 9 atoms ............................................................................................................................................. [1]
(f) react together to form slag in the blast furnace ................................................................... and .................................................................. [2]
(g) belongs to a homologous series whose general formula is CnH2n+2 ............................................................................................................................................. [1]
(h) is manufactured by the catalytic addition of steam to ethene ............................................................................................................................................. [1]
(i) is a gas that is approximately 78% of clean, dry air. ............................................................................................................................................. [1] [Total: 10]
2 Atoms are made of electrons, neutrons and protons.
(a) State which of these particles are found in the nucleus of an atom [1]
(b) Atoms of the same element are known as isotopes.
32 16S and 34 16S are isotopes of sulfur.
(i) Complete Table 2.1 to show the number of electrons, neutrons and protons in one atom or ion of these isotopes. Table 2.1 isotope electrons neutrons protons 34 16S 32 16S2–
[3]
(ii) Table 2.2 shows the relative masses and the percentage abundances of the two isotopes in a sample of sulfur. Table 2.2 relative mass of isotope percentage abundance of isotope 32 95 34 5
Calculate the relative atomic mass of this sample of sulfur to one decimal place.
relative atomic mass = [2]
(iii) The relative atomic masses of all elements are compared to one atom of an isotope.
Identify this isotope [1] , ,
(c) Ions are atoms or groups of atoms that have gained or lost one or more electrons.
An oxygen atom has the electronic configuration of 2,6.
Give the formula of one atom and one positive ion that has the same electronic configuration as O2–. • atom • positive ion [2]
[Total: 9] , ,
(a) State which of these particles are found in the nucleus of an atom. ............................................................................................................................................. [1]
(b) Atoms of the same element are known as isotopes. 16S and 34 32 16S are isotopes of sulfur. (i) Complete Table 2.1 to show the number of electrons, neutrons and protons in one atom or ion of these isotopes. Table 2.1 electrons isotope neutrons protons 34 16S 32 16S2– [3]
(ii) Table 2.2 shows the relative masses and the percentage abundances of the two isotopes in a sample of sulfur. Table 2.2 percentage abundance of isotope relative mass of isotope 32 95 5 34 Calculate the relative atomic mass of this sample of sulfur to one decimal place. relative atomic mass = .............................. [2]
(iii) The relative atomic masses of all elements are compared to one atom of an isotope. Identify this isotope. ..................................................................................................................................... [1] , ,
(c) Ions are atoms or groups of atoms that have gained or lost one or more electrons. An oxygen atom has the electronic configuration of 2,6. Give the formula of one atom and one positive ion that has the same electronic configuration as O2–. • atom .................................................................................................................................. • positive ion ........................................................................................................................ [2] [Total: 9]
3 This question is about zinc and compounds of zinc.
(a) Zinc is held together by electrostatic forces of attraction between particles.
(i) Name the type of bonding in zinc [1]
(ii) Name the two types of particles held together by the bonding in (a)(i). 1 2 [2]
(iii) Name the type of particle whose movement allows zinc to conduct electricity [1]
(b) Zinc is present in alloys such as brass.
(i) State the meaning of the term alloy [1]
(ii) Name the substance that is present in brass, other than zinc [1]
(c) Zinc sulfate crystals are made by the reaction between zinc carbonate and dilute sulfuric acid, using the following steps.
step 1 An excess of powdered zinc carbonate is added to dilute sulfuric acid.
step 2 Excess zinc carbonate is separated from aqueous zinc sulfate by filtration.
step 3 Aqueous zinc sulfate is heated until a saturated solution is formed.
step 4 The saturated solution is allowed to cool and crystallise.
step 5 The crystals are removed and dried.
(i) Give two observations which show that the zinc carbonate is in excess in step 1. 1 2 [2]
(ii) Name the filtrate in step 2 [1] , ,
(iii) Name a compound, other than zinc carbonate, that can be added to dilute sulfuric acid to produce aqueous zinc sulfate in step 1 [1]
(iv) State what is meant by the term saturated solution [2]
(v) Step 1 is repeated using large pieces of zinc carbonate instead of powdered zinc carbonate.
All other conditions are the same.
The rate of reaction decreases.
Explain why the rate of reaction decreases. Give your answer in terms of particles [2]
(vi) Hydrated crystals form in step 4.
State what is meant by the term hydrated [1]
[Total: 15] , ,
(a) Zinc is held together by electrostatic forces of attraction between particles. (i) Name the type of bonding in zinc. ..................................................................................................................................... [1]
(ii) Name the two types of particles held together by the bonding in (a)(i). 1 ........................................................................................................................................ 2 ........................................................................................................................................ [2]
(iii) Name the type of particle whose movement allows zinc to conduct electricity. ..................................................................................................................................... [1]
(b) Zinc is present in alloys such as brass. (i) State the meaning of the term alloy. ..................................................................................................................................... [1]
(ii) Name the substance that is present in brass, other than zinc. ..................................................................................................................................... [1]
(c) Zinc sulfate crystals are made by the reaction between zinc carbonate and dilute sulfuric acid, using the following steps. An excess of powdered zinc carbonate is added to dilute sulfuric acid. step 1 Excess zinc carbonate is separated from aqueous zinc sulfate by filtration. step 2 Aqueous zinc sulfate is heated until a saturated solution is formed. step 3 The saturated solution is allowed to cool and crystallise. step 4 The crystals are removed and dried. step 5 (i) Give two observations which show that the zinc carbonate is in excess in step 1. 1 ........................................................................................................................................ 2 ........................................................................................................................................ [2]
(ii) Name the filtrate in step 2. ..................................................................................................................................... [1] , ,
(iii) Name a compound, other than zinc carbonate, that can be added to dilute sulfuric acid to produce aqueous zinc sulfate in step 1. ..................................................................................................................................... [1]
(iv) State what is meant by the term saturated solution. ........................................................................................................................................... ..................................................................................................................................... [2]
(v) Step 1 is repeated using large pieces of zinc carbonate instead of powdered zinc carbonate. All other conditions are the same. The rate of reaction decreases. Explain why the rate of reaction decreases. Give your answer in terms of particles. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [2]
(vi) Hydrated crystals form in step 4. State what is meant by the term hydrated. ..................................................................................................................................... [1] [Total: 15]
4 This question is about compounds of sulfur.
(a) Sulfuric acid is manufactured in a four‑stage process.
stage 1 Sulfur dioxide is produced from ores containing sulfur.
stage 2 Sulfur dioxide reacts with oxygen to form sulfur trioxide.
stage 3 Sulfur trioxide reacts with concentrated sulfuric acid to form oleum, H2S2O7.
stage 4 Oleum reacts with water to form concentrated sulfuric acid.
(i) Iron pyrite is an ore containing sulfur. The ore contains a compound with the formula FeS2.
FeS2 reacts with oxygen in the air to produce sulfur dioxide.
Balance the symbol equation for this reaction. 4FeS2 + O2 SO2 + Fe2O3
[1]
(ii) Complete the dot‑and‑cross diagram in Fig. 4.1 to show the electronic configuration in an oxygen molecule, O2. Show outer‑shell electrons only. O O Fig. 4.1
[2]
(b) (i) State three typical conditions for the reaction between sulfur dioxide and oxygen in stage 2. 1 2 3 [3] , ,
(ii) Write a symbol equation for the reaction that occurs in stage 2 [1]
(iii) Write the symbol equation for the reaction in stage 3 [1]
(c) Sulfuric acid reacts with carbon. The equation for the reaction is shown. 2H2SO4 + C CO2 + 2H2O + 2SO2
Give the oxidation number of carbon in: • C • CO2 [2]
(d) Dilute sulfuric acid reacts with sodium hydrogencarbonate, NaHCO3, to produce carbon dioxide gas, CO2. H2SO4(aq) + 2NaHCO3(s) Na2SO4(aq) + 2CO2(g) + 2H2O(l)
4.20 g of NaHCO3 is added to excess dilute sulfuric acid.
Calculate the volume of CO2(g), measured at r.t.p., produced using the following steps. • Calculate the number of moles of NaHCO3 in 4.20 g.
The Mr of NaHCO3 is 84 mol • Deduce the number of moles of CO2(g) that are produced mol • Calculate the volume of CO2(g) produced in cm3.
One mole of any gas occupies 24 000 cm3 at r.t.p cm3
[3]
[Total: 13] , ,
(a) Sulfuric acid is manufactured in a four‑stage process. Sulfur dioxide is produced from ores containing sulfur. stage 1 Sulfur dioxide reacts with oxygen to form sulfur trioxide. stage 2 Sulfur trioxide reacts with concentrated sulfuric acid to form oleum, H2S2O7. stage 3 Oleum reacts with water to form concentrated sulfuric acid. stage 4 (i) Iron pyrite is an ore containing sulfur. The ore contains a compound with the formula FeS2. FeS2 reacts with oxygen in the air to produce sulfur dioxide. Balance the symbol equation for this reaction. .....SO2 + .....Fe2O3 4FeS2 + .....O2 [1]
(ii) Complete the dot‑and‑cross diagram in Fig. 4.1 to show the electronic configuration in an oxygen molecule, O2. Show outer‑shell electrons only. O O Fig. 4.1 [2]
(b) (i) State three typical conditions for the reaction between sulfur dioxide and oxygen in stage 2. 1 ........................................................................................................................................ 2 ........................................................................................................................................ 3 ........................................................................................................................................ [3] , ,
(ii) Write a symbol equation for the reaction that occurs in stage 2. ..................................................................................................................................... [1]
(iii) Write the symbol equation for the reaction in stage 3. ..................................................................................................................................... [1]
(c) Sulfuric acid reacts with carbon. The equation for the reaction is shown. CO2 + 2H2O + 2SO2 2H2SO4 + C Give the oxidation number of carbon in: • .............................. C • CO2. .............................. [2]
(d) Dilute sulfuric acid reacts with sodium hydrogencarbonate, NaHCO3, to produce carbon dioxide gas, CO2. Na2SO4(aq) + 2CO2(g) + 2H2O(l) H2SO4(aq) + 2NaHCO3(s) 4.20 g of NaHCO3 is added to excess dilute sulfuric acid. Calculate the volume of CO2(g), measured at r.t.p., produced using the following steps. • Calculate the number of moles of NaHCO3 in 4.20 g. The Mr of NaHCO3 is 84. .............................. mol • Deduce the number of moles of CO2(g) that are produced. .............................. mol Calculate the volume of CO2(g) produced in cm3. • One mole of any gas occupies 24 000 cm3 at r.t.p. .............................. cm3 [3] [Total: 13]
5 Ethanoic acid is manufactured in the reaction between methanol and carbon monoxide.
An equilibrium mixture is produced. CH3OH(g) + CO(g) CH3COOH(g)
(a) State two characteristics of an equilibrium. 1 2 [2]
(b) Both a high yield of ethanoic acid and a high rate of reaction are needed.
The reaction is carried out at 300 °C.
The forward reaction is exothermic.
(i) State the disadvantage of using a temperature: • below 300 °C • above 300 °C [2]
(ii) Complete Table 5.1 using only the words increases, decreases or no change. Table 5.1 effect on the equilibrium concentration of CH3COOH(g) effect on the rate of the forward reaction catalyst is added increases pressure is increased
[3]
(iii) Suggest which element from the list is a suitable catalyst for the reaction.
Give a reason for your answer. aluminium carbon cobalt magnesium sodium catalyst reason [2] , ,
(c) Ethanoic acid is a member of the carboxylic acid homologous series.
(i) Name the carboxylic acid that contains only one carbon atom [1]
(ii) State the molecular formula of a carboxylic acid that contains four carbon atoms [1]
(d) Carboxylic acids react with alcohols to form esters.
(i) Draw the displayed formula of the ester which contains two carbon atoms.
[2]
(ii) Propyl butanoate is an ester.
Name the carboxylic acid and alcohol that react to produce propyl butanoate. carboxylic acid alcohol [2]
(e) An organic compound has the following composition by mass:
C, 58.82%; H, 9.80%; O, 31.38%.
Calculate the empirical formula of the compound.
empirical formula = [3]
[Total: 18] , ,
(a) State two characteristics of an equilibrium. 1 ................................................................................................................................................ 2 ................................................................................................................................................ [2]
(b) Both a high yield of ethanoic acid and a high rate of reaction are needed. The reaction is carried out at 300 °C. The forward reaction is exothermic. (i) State the disadvantage of using a temperature: • below 300 °C ........................................................................................................................................... • above 300 °C. ........................................................................................................................................... [2]
(ii) Complete Table 5.1 using only the words increases, decreases or no change. Table 5.1 effect on the rate of the effect on the equilibrium concentration of CH3COOH(g) forward reaction catalyst is added increases pressure is increased [3]
(iii) Suggest which element from the list is a suitable catalyst for the reaction. Give a reason for your answer. aluminium carbon cobalt magnesium sodium catalyst .............................................................................................................................. reason ............................................................................................................................... [2] , ,
(c) Ethanoic acid is a member of the carboxylic acid homologous series. (i) Name the carboxylic acid that contains only one carbon atom. ..................................................................................................................................... [1]
(ii) State the molecular formula of a carboxylic acid that contains four carbon atoms. ..................................................................................................................................... [1]
(d) Carboxylic acids react with alcohols to form esters. (i) Draw the displayed formula of the ester which contains two carbon atoms. [2]
(ii) Propyl butanoate is an ester. Name the carboxylic acid and alcohol that react to produce propyl butanoate. carboxylic acid ................................................................................................................... alcohol ............................................................................................................................... [2]
(e) An organic compound has the following composition by mass: C, 58.82%; H, 9.80%; O, 31.38%. Calculate the empirical formula of the compound. empirical formula = .............................. [3] [Total: 18]
6 This question is about the Periodic Table.
(a) State the name given to Group I elements [1]
(b) State which Group I element is least reactive [1]
(c) Lithium is in Group I of the Periodic Table.
When lithium is added to water a chemical reaction occurs.
(i) Give two observations when lithium is added to water. 1 2 [2]
(ii) Write a symbol equation for this reaction [2]
(d) Group I elements have lower melting points and lower boiling points than transition elements.
Describe two other physical properties of Group I elements that are different from transition elements. 1 2 [2]
(e) The Group VII elements are known as the halogens.
(i) Give the physical state and colour of chlorine at room temperature and pressure. state colour [2]
(ii) When chlorine is passed through aqueous potassium bromide, a displacement reaction occurs.
The equation for the reaction is shown. Cl 2 + 2KBr 2KCl + Br2
Write an ionic equation for the reaction [2] , ,
(iii) Iodine and chlorine react at high temperatures to form iodine monochloride, ICl .
The equation for the reaction is shown. I2(g) + Cl 2(g) 2ICl (g)
The structures of the molecules involved in the reaction are I–I, Cl –Cl and I–Cl . Table 6.1 bond bond energy in kJ / mol I–I 150 Cl –Cl 242 I–Cl 218
Calculate the enthalpy change, ΔH, for the reaction using the bond energies in Table 6.1.
Use the following steps. • Calculate the total amount of energy required to break the bonds in 1 mol of I2(g) and 1 mol of Cl 2(g) kJ • Calculate the total amount of energy released when the bonds in 2 mol of ICl (g) are formed kJ • Calculate the enthalpy change, ΔH, for the reaction.
Your answer should include a sign kJ / mol
[3]
[Total: 15] , , Group The Periodic Table of Elements 1 H hydrogen 1 2 He helium 4 I II III IV V VI VII VIII 3 Li lithium 7 4 Be beryllium 9 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23 12 Mg magnesium 24 19 K potassium 39 20 Ca calcium 40 37 Rb rubidium 85 38 Sr strontium 88 55 Cs caesium 133 56 Ba barium 137 87 Fr francium – 88 Ra radium – 5 B boron 11 13 Al aluminium 27 31 Ga gallium 70 49 In indium 115 81 Tl thallium 204 113 Nh nihonium – 6 C carbon 12 14 Si silicon 28 32 Ge germanium 73 50 Sn tin 119 82 Pb lead 207 22 Ti titanium 48 40 Zr zirconium 91 72 Hf hafnium 178 104 Rf rutherfordium – 23 V vanadium 51 41 Nb niobium 93 73 Ta tantalum 181 105 Db dubnium – 24 Cr chromium 52 42 Mo molybdenum 96 74 W tungsten 184 106 Sg seaborgium – 25 Mn manganese 55 43 Tc technetium – 75 Re rhenium 186 107 Bh bohrium – 26 Fe iron 56 44 Ru ruthenium 101 76 Os osmium 190 108 Hs hassium – 27 Co cobalt 59 45 Rh rhodium 103 77 Ir iridium 192 109 Mt meitnerium – 28 Ni nickel 59 46 Pd palladium 106 78 Pt platinum 195 110 Ds darmstadtium – 29 Cu copper 64 47 Ag silver 108 79 Au gold 197 111 Rg roentgenium – 30 Zn zinc 65 48 Cd cadmium 112 80 Hg mercury 201 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14 15 P phosphorus 31 33 As arsenic 75 51 Sb antimony 122 83 Bi bismuth 209 115 Mc moscovium – 8 O oxygen 16 16 S sulfur 32 34 Se selenium 79 52 Te tellurium 128 84 Po polonium – 9 F fluorine 19 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 85 At astatine – 117 Ts tennessine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 118 Og oganesson – 21 Sc scandium 45 39 Y yttrium 89 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 139 89 Ac lanthanoids actinoids The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinium – 58 Ce cerium 140 90 Th thorium 232 59 Pr praseodymium 141 91 Pa protactinium 231 60 Nd neodymium 144 92 U uranium 238 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150 94 Pu plutonium – 63 Eu europium 152 95 Am americium – 64 Gd gadolinium 157 96 Cm curium – 65 Tb terbium 159 97 Bk berkelium – 66 Dy dysprosium 163 98 Cf californium – 67 Ho holmium 165 99 Es einsteinium – 68 Er erbium 167 100 Fm fermium – 69 Tm thulium 169 101 Md mendelevium – 70 Yb ytterbium 173 102 No nobelium – 71 Lu lutetium 175 103 Lr lawrencium – , ,
(a) State the name given to Group I elements. ............................................................................................................................................. [1]
(b) State which Group I element is least reactive. ............................................................................................................................................. [1]
(c) Lithium is in Group I of the Periodic Table. When lithium is added to water a chemical reaction occurs. (i) Give two observations when lithium is added to water. 1 ........................................................................................................................................ 2 ........................................................................................................................................ [2]
(ii) Write a symbol equation for this reaction. ..................................................................................................................................... [2]
(d) Group I elements have lower melting points and lower boiling points than transition elements. Describe two other physical properties of Group I elements that are different from transition elements. 1 ................................................................................................................................................ 2 ................................................................................................................................................ [2]
(e) The Group VII elements are known as the halogens. (i) Give the physical state and colour of chlorine at room temperature and pressure. state .................................................................................................................................. colour ................................................................................................................................ [2]
(ii) When chlorine is passed through aqueous potassium bromide, a displacement reaction occurs. The equation for the reaction is shown. 2KCl + Br2 Cl 2 + 2KBr Write an ionic equation for the reaction. ..................................................................................................................................... [2] , ,
(iii) Iodine and chlorine react at high temperatures to form iodine monochloride, ICl . The equation for the reaction is shown. 2ICl (g) I2(g) + Cl 2(g) The structures of the molecules involved in the reaction are I–I, Cl –Cl and I–Cl . Table 6.1 bond bond energy in kJ / mol 150 I–I 242 Cl –Cl 218 I–Cl Calculate the enthalpy change, ΔH, for the reaction using the bond energies in Table 6.1. Use the following steps. • Calculate the total amount of energy required to break the bonds in 1 mol of I2(g) and 1 mol of Cl 2(g). .............................. kJ • Calculate the total amount of energy released when the bonds in 2 mol of ICl (g) are formed. .............................. kJ • Calculate the enthalpy change, ΔH, for the reaction. Your answer should include a sign. .............................. kJ / mol [3] [Total: 15] , , oganesson krypton helium VIII xenon Og argon radon He Ne Rn Xe neon 131 Ar Kr 118 54 84 18 20 36 40 86 10 4 – – 2 lawrencium tennessine bromine astatine lutetium chlorine fluorine iodine 35.5 VII Lu Cl 103 175 127 Br Ts 117 At Lr 35 17 19 53 80 85 71 F I – – – 9 livermorium ytterbium nobelium polonium selenium tellurium oxygen No Yb Po Se sulfur Lv Te 102 173 128 116 VI O 16 16 32 34 52 79 S 84 70 – – – 8 mendelevium phosphorus moscovium antimony nitrogen bismuth thulium arsenic Tm Md Mc Sb As 101 169 122 209 115 Bi N P 69 14 15 31 33 51 75 83 V 7 – – germanium flerovium fermium carbon erbium Fm silicon Ge Sn Pb 100 167 207 Er 114 119 lead Fl Si IV C 82 12 14 28 32 50 73 68 tin – – 6 einsteinium aluminium nihonium holmium thallium gallium indium Ga boron Ho Nh Es 165 204 In 115 113 Al Tl III 13 81 27 31 B 49 70 67 99 11 – – 5 copernicium dysprosium californium cadmium mercury Cd Cn Hg Dy Zn 201 163 Cf 112 112 zinc 80 48 30 65 98 66 – – roentgenium The Periodic Table of Elements berkelium terbium copper Cu Rg Ag Au Bk Tb silver 159 197 108 gold 111 47 64 29 65 79 97 – – darmstadtium gadolinium palladium platinum Cm curium Gd nickel Pd Ds 157 195 106 110 Pt Ni 64 28 46 59 96 78 The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). – – Group meitnerium americium europium rhodium Am iridium cobalt Co Rh Eu Mt 152 103 109 192 Ir 63 27 45 59 95 77 – – ruthenium samarium plutonium hydrogen hassium osmium Sm Os Ru Pu Hs Fe 101 108 150 190 iron H 26 44 56 62 94 76 1 1 – – promethium manganese technetium neptunium bohrium rhenium Pm Mn Np Re Bh 107 186 Tc 93 61 25 75 43 55 – – – – molybdenum seaborgium neodymium chromium tungsten uranium Mo Nd Sg Cr 144 238 106 184 W U 60 92 42 52 74 96 24 – atomic symbol relative atomic mass atomic number praseodymium protactinium vanadium tantalum dubnium niobium Key Db Nb name Pa Ta 105 181 141 231 Pr 23 41 51 73 93 V 59 91 – rutherfordium zirconium hafnium titanium thorium cerium Ce Th 232 104 140 178 Hf Rf Zr Ti 58 22 40 48 72 91 90 – lanthanoids lanthanum scandium 89–103 actinoids actinium 57–71 yttrium Ac Sc La 139 57 89 Y 21 39 45 89 – magnesium strontium beryllium calcium barium radium Mg Ca Ra Ba Be 137 Sr 24 40 88 12 20 38 88 56 II 9 – 4 lanthanoids actinoids potassium francium rubidium caesium sodium lithium Na Rb Cs 133 Fr Li 19 37 55 87 23 39 85 K 11 3 7 – I