Microscopic World I. Part A Unit-based exercise. Topic 2. Unit 5 Atomic structure. Fill in the blanks. True or false. Multiple choice questions

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1 Topic 2 Microscopic World I Part Unit-based exercise Unit 5 tomic structure Fill in the blanks 1 ll elements are made of atoms. 2 Elements exist in different states at room conditions. Silver and sulphur are solids ; bromine and mercury are liquids ; chlorine and oxygen are gases. 3 Elements can be classified into three main groups: metals, metalloids and non-metals. 4 The melting and boiling points of non-metals are usually low. 5 Metals are usually good conductors of heat and electricity. 6 oron, silicon and germanium are metalloids. 7 toms consist of a nucleus in the centre and a cloud of electrons that move in circular orbits called shells. 8 The nucleus of an atom contains two types of particles : protons and neutrons. 9 The of protons in an atom of an element equals the atomic of the element. 10 The sum of the s of protons and neutrons in an atom equals the mass of the atom. 11 ifferent atoms of an element with the same of protons but different of neutrons are isotopes. 12 The weighted average relative isotopic mass of all the naturally occurring isotopes of an element on the 12 = scale is the relative atomic mass of that element. 13 The way in which electrons are arranged in an atom is its electronic arrangement. 14 The electronic arrangement of an atom can be represented by an electron diagram. 15 In a hydrogen atom, the region in which there is 95% chance of finding the electron is called an orbital. True or false ecide whether each of the following statements is true or false. 16 t room temperature and pressure, all F metals are solids. 17 Solid non-metals are usually dull in T appearance. 18 Silicon is a metalloid. T 19 Molten sulphur is a good conductor F of electricity. 20 The symbol of magnesium is Ma. F Part Unit 5 Part Unit 5 21 The atomic of an element T equals the of electrons in an atom of that element. 22 n atom of an element must F contain equal of protons and neutrons. 23 ll atoms contain neutrons. F sodium atom ( 1 1Na) contains 11 neutrons. 25 fluorine atom contains 9 electrons. T 26 Isotopes of an element have the same T of protons. 27 Isotopes of an element have the same F mass. 28 The atomic of oxygen is 8. T 29 In an atom, the second electron shell F can hold a maximum of 10 electrons. 30 calcium atom contains 3 occupied F electron shells. Multiple choice questions 31 Which of the following combinations is correct? Element Symbol alcium hlorine h Iron Ir Potassium K Which of the following elements is a gas at room temperature and pressure? arbon Iron Oxygen Silicon F 33 Which of the following elements is a solid at room temperature and pressure? l N Ne S 34 Which of the following conbinations is INORRET? Element State at room temperature and pressure rgon gas eryllium liquid alcium solid Phosphorus solid 35 onsider the information below: Element Melting point ( ) oiling point ( ) W X Y Z Which of the following elements is a gas at 25? W X Y Z 36 The table shows the melting points and boiling points of four substances at 1 atm pressure. Substance Melting point ( ) oiling point ( ) W X Y 7 60 Z Which of the following substances exists as a liquid at 100 and 1 atm pressure? W X Y Z 1 2

2 37 onsider the following information: Substance Melting point ( ) oiling point ( ) W 50 5 X 4 81 Y Z Which of the following solids is likely to be a metal? W X Y Z 42 Which of the following statements concerning silicon is INORRET? 45 n atom has 28 electrons and 30 neutrons. Which of the following combinations concerning the atom is correct? tomic Mass Which of the following atoms are isotopes? I and III II and III I and IV II and IV 50 The following table shows the relative abundance of isotopes of lithium: Which of the following substances is / are in liquid state at room temperature and pressure? W only X only X and Z only Y and Z only 38 Which of the following elements is a metal? luminium arbon Germanium Neon 39 Which of the following elements is a metalloid? oron opper Helium Phosphorus 40 Which of the following elements is a nonmetal? a e s Kr 41 onsider the information below: Solid Melting point Electrical conductivity Solubility in water W low non-conducting soluble X high non-conducting soluble Y high good insoluble Z very high non-conducting insoluble Properties of silicon are in between metals and non-metals. Silicon is brittle. Silicon can be used to make semiconductors. Silicon is soluble in water. 43 Which of the following statements concerning the basic structure of an atom is correct? n atom must have equal s of protons and neutrons. The mass of one proton is approximately equal to that of an electron. neutron carries a small negative electrical charge. proton carries a small positive electrical charge. 44 The atomic of an element X is 10. n atom of X has a mass 22. Which of the following combinations concerning the atom of X is correct? protons neutrons electrons Part Unit 5 Part Unit 5 46 Which of the following combinations concerning the atomic structure of the atom X is correct? protons neutrons electrons Which of the following particles contains the same of neutrons as 1 6S? Na 24 12Mg Si P 48 Which of the following combinations concerning isotopes of an element is correct? neutrons protons electrons different same different same different same different same same same same same 49 onsider the following information of four atoms: tom tomic Mass neutrons I II III IV Isotope Relative abundance (%) 6 Li Li 92.6 The relative atomic mass of lithium is g g. 51 Element X has two isotopes, 85 X and 87 X. The table below lists the relative abundance of each isotope. Isotope Relative abundance (%) 85 X X 27.9 What is the relative atomic mass of X? Metal X has three isotopes, 189 X, 190 X and 192 X. The graph below shows the relative abundance of the isotopes. 3 4

3 What is the relative atomic mass of X? Element X occurs in nature as two isotopes, 79 X and 81 X. If the relative atomic mass of X is 79.9, what is the relative abundance of the 81 X isotope? 30.0% 35.0% 40.0% 45.0% 54 The relative atomic mass of potassium is It is NOT a whole because the mass of electrons has been taken into account. fractional protons exist. fractional neutrons exist. isotopes of potassium exist. 55 The atomic mass of element X is X has two isotopes, 69 X and a X, and the relative abundance of 69 X is 65.0%. What is the value of a? The atomic of an element X is 15. The electronic arrangement of an atom of X is 2,13. 2,8,5. 2,10,3. 2,4,8,1. 57 Which of the following represents the electronic arrangement of an atom of a metalloid? 2,1 2,2 2,3 2,4 58 The electron diagram of an atom of element X is shown below: (Only electrons in the outermost shell are shown.) X could be l. P. S. Si. 59 Which of the following descriptions of metals is / are correct? They are all solids at room conditions. (2) They are good conductors of electricity. (3) They are all stored in paraffin oil. only (2) only and (3) only (2) and (3) only 60 Which of the following descriptions concerning non-metals are correct? Their melting points are often low. (2) They are brittle if they are solids. (3) They are poor conductors of heat. and (2) only and (3) only (2) and (3) only, (2) and (3) 61 Which of the following statements concerning metalloids is / are correct? ll metalloids are solids. (2) Gallium is a metalloid. (3) Metalloids cannot conduct electricity at room temperature. only (2) only and (3) only (2) and (3) only 5 Part Unit 5 Part Unit Which of the following statements concerning isotopes of an element is / are correct? They have different of neutrons. (2) They have different atomic s. (3) They have the same mass. only (2) only and (3) only (2) and (3) only 63 onsider the following information concerning atoms P and Q: tom protons neutrons electrons P Q Which of the following statements concerning P and Q is / are correct? P is an atom of a non-metal. (2) Q is an atom of a metal. (3) P and Q are isotopes of the same element. only (2) only and (3) only (2) and (3) only 64 onsider the information below: Particle X Y Z protons electrons neutrons Which of the following statements concerning the particles is / are correct? X and Z have the same mass. (2) X and Y are isotopes. (3) Y and Z have the same electronic arrangement. only (2) only and (3) only (2) and (3) only 65 The atomic of element X is 15. It has only one isotope with a mass 31. Which of the following statements concerning X is / are correct? X is a gas at room temperature and pressure. (2) There are 5 electrons in the outermost shell of an atom of X. (3) There are 15 neutrons in the nucleus of an atom of X. only (2) only and (3) only (2) and (3) only 66 n atom of element X has an electronic arrangement 2,8,1. Which of the following statements concerning X are correct? It is a metal. (2) Its atom has 11 protons. (3) Its symbol is K. and (2) only and (3) only (2) and (3) only, (2) and (3) The isotope cobalt-60 ( 2 7o) is used to destroy cancer cells in the human body. Which of the 60 following statements concerning a 2 7o atom are correct? It contains 33 neutrons. (2) It contains 27 protons. (3) The of electrons it has is different from another isotope of cobalt. and (2) only and (3) only (2) and (3) only, (2) and (3)

4 irections : Each question (Questions 68 75) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. Short questions 71 omplete the following table by (12 marks) a) filling in the names or symbols of the elements; b) classifying each element into metal, metalloid or non-metal. Element Symbol Metal / Metalloid / Non-metal rgon r non-metal 1st statement 2nd statement 68 arbon is a solid at room temperature and arbon is a non-metal. pressure. 69 toms are electrically neutral. toms have the same of protons and electrons. 70 The of neutrons and that of protons n atom is electrically neutral. in an atom should be the same. 71 The atomic of sulphur ( 1 6S) is S atom contains 16 neutrons. Part Unit 5 arbon non-metal alcium a metal Fluorine F non-metal Germanium Ge metalloid Lithium Li metal Magnesium Mg metal Neon Ne non-metal Nitrogen N non-metal Potassium K metal Phosphorus P non-metal X and 2 6Y are isotopes. 24X and 2 6Y have the same mass but different atomic s. 73 Isotopes of a given element have different Isotopes of a given element have different relative isotopic masses. s of neutrons. 74 The relative atomic mass of magnesium is not a Magnesium has isotopes. whole. 75 Isotopes of an element have the same mass. ll atoms of an element contain the same of electrons. Silicon Si metalloid (0.5 x 24) 72 omplete the following table. (20 marks) tom tomic Mass Symbol protons neutrons electrons Oxygen O Sodium Na luminium l Sulphur 16 16S hlorine l Potassium K alcium a Iron Fe (0.5 x 40) Part 7 55

5 73 Look at the list of elements. boron chlorine copper fluorine magnesium nickel nitrogen phosphorus nswer the following questions. hoose all your answers from the list. Each element can be used once, more than once or not at all. (6 marks) a) Write down the name of a greenish yellow gas. chlorine b) Write down the name of an element that forms compounds that are blue in colour. copper c) Write down the name of the element whose atom contains 15 protons. b) Which species in the above table is / are negatively charged? (1 mark) Species (vi) & (viii) / nitride ion and fluoride ion (0.5 x 2) c) In which group of the periodic table should species (iii) be placed? Explain your answer. (2 marks) Group IV; it has 4 electrons in its outermost shell. d) State the relationship between species (ix) and (x). (1 mark) Species (ix) is the cation of species (x) / (ix) and (x) are the ion and atom of the same element. 75 a) Write down the chemical formula for each of the following compounds. (8 marks) phosphorus Name hemical formula d) Write down the name of the element whose atom has an electronic arrangement 2,5. luminium hydroxide l(oh) 3 nitrogen mmonium dichromate (NH 4) 2r 2O 7 e) Write down the name of a metalloid. alcium phosphate a 3(PO 4) 2 boron opper(ii) chloride ul 2 f) Write down the name of an element that forms ions which is green in aqueous solution. Iron(III) oxide Fe 2O 3 Magnesium hydroxide Mg(OH) 2 nickel Potassium carbonate K 2O 3 74 a) omplete the following table. (20 marks) Sodium sulphite Na 2SO 3 (1 x 8) Part Species tomic Mass protons neutrons electrons Electronic arrangement b) Write down the names of the following compounds. (8 marks) Part i) eryllium atom ,2 hemical formula Name ii) Neon atom ,8 KHO 3 potassium hydrogencarbonate iii) Silicon atom ,8,4 Fe 2(SO 4) 3 iron(iii) sulphate iv) Phosphorus atom ,8,5 u(oh) 2 copper(ii) hydroxide v) Potassium ion ,8,8 Mg 3N 2 magnesium nitride vi) Nitride ion ,8 Zn(NO 3) 2 zinc nitrate vii) Magnesium ion ,8 NaS sodium sulphide viii) Fluoride ion ,8 l 2O 3 aluminium oxide ix) Sodium ion ,8 gl silver chloride (1 x 8) x) Sodium atom ,8,1 (0.5 x 40) 56 57

6 76 omplete the following table. (21 marks) ii) Magnesium and nitrogen ation nion ompound Name Formula Name Formula Name Formula ammonium NH 4 + carbonate O 3 2 olour of aqueous solution ammonium carbonate (NH 4) 2O 3 colourless copper(ii) u 2+ nitrate NO 3 copper(ii) nitrate u(no 3) 2 blue iron(ii) Fe 2+ sulphate SO 4 2 potassium K + permanganate MnO 4 iron(ii) sulphate FeSO 4 pale green potassium permanganate KMnO 4 purple nickel(ii) Ni 2+ chloride l nickel(ii) chloride Nil 2 green aluminium l 3+ iodide I aluminium iodide ll 3 colourless chromium(iii) r 3+ chloride l chromium(iii) chloride rl 3 green sodium Na + dichromate r 2O 7 2 sodium dichromate Na 2r 2O 7 orange zinc Zn 2+ bromide r zinc bromide Znr 2 colourless (0.5 x 42) 77 a) Use an electron diagram to show the electron transfer when each of the following pairs of elements combine, showing electrons in the outermost shells only. (3 marks) iii) Sodium and sulphur i) alcium and chlorine Part Part b) Use an electron diagram to show the sharing of electrons when each of the following pairs of elements combine, showing electrons in the outermost shells only. (3 marks) i) Phosphorus and chlorine 58 59

7 ii) Oxygen and hydrogen iii) hlorine and fluorine 78 alculate the formula masses or relative molecular masses of the following substances. (5 marks) Part Substance hemical formula Relative atomic mass(es) Formula mass / relative molecular mass Oxygen O 2 O = arbon dioxide O 2 = 12.0 O = 16.0 Potassium nitrate KNO 3 O = 16.0 N = 14.0 K = 39.1 alcium hydroxide a(oh) 2 O = 16.0 H = 1.0 a = 40.1 Iron(III) sulphate Fe 2(SO 4) 3 S =.1 O = 16.0 Fe = (1 x 5) 79 Phosphorus and nitrogen are in Group V of the periodic table and both elements form hydrides. Phosphine, PH 3, reacts to form phosphonium ions, PH 4 +, in a way similar to that by which ammonia, NH 3, forms ammonium ions, NH 4 +. a) Give the name of the type of bond formed when PH 3 reacts with an H + ion. (1 mark) ative covalent bond 60