9.2. Periodicity of chemical properties of the elements in Period 3
A subsection of Chemistry, 9701, through 9. The Periodic Table: chemical periodicity
Listing 10 of 224 questions
State and explain the variation in the oxidation numbers of the chlorides of the elements Na, Mg, Al and Si. Describe the reaction of phosphorus(chloride with water, and write an equation for the reaction. When microwave radiation is passed through phosphorus(chloride, PCl3, at low pressure, a new chloride of phosphorus, B, is formed. B contains 69.6% by mass of chlorine and 30.4% by mass of phosphorus, and its Mr is approximately 200. Calculate the empirical and molecular formulae of B. Assuming phosphorus and chlorine show their typical valencies, draw the displayed formula of B, showing all bonds and lone pairs. Calculate the oxidation number of phosphorus in B. One mole of B reacts with four moles of water. Suggest the structure of the phosphorus-containing product of this reaction.
9701_s11_qp_41
THEORY
2011
Paper 4, Variant 1
View
Oxides are compounds which usually contain oxygen combined with one other element. Oxides are classifi ed as follows. acidic alkaline amphoteric basic Using these terms only, complete the table to describe the oxides of the elements of the third period of the Periodic Table sodium to sulfur. Na2O MgO Al 2O3 SiO2 P4O10 SO2 Cl 2O7 acidic Give the names of two elements from sodium to chlorine which form more than one oxide. and Sodium reacts with water. Describe, as fully as you can, what you would see when a piece of sodium is reacted with water. Write an equation for the reaction of sodium with water. Sulfur dioxide is present in small, but signifi cant, amounts in the Earth’s atmosphere. State one way by which sulfur dioxide enters the atmosphere. Give the formula of another sulfur compound which is formed in the atmosphere from sulfur dioxide. What are the environmental consequences of the compound you have identifi ed in ? Sulfur dioxide is used as a food preservative. What property of sulfur dioxide enables it to act in this way? Another sulfur compound which is present in the Earth’s atmosphere is carbonyl sulfi de, OCS. The sequence of atoms in the molecule is oxygen-carbon-sulfur and the molecule is not cyclic. Draw a ‘dot-and-cross’ diagram of the OCS molecule. Show outer electrons only. Suggest a value for the O – C – S bond angle.
9701_s12_qp_21
THEORY
2012
Paper 2, Variant 1
View
The elements of the third period of the Periodic Table, sodium to sulfur, all form chlorides by direct combination. Sulfur forms a number of chlorides which are liquid at room temperature. Which other element of the third period forms a chloride which is liquid at room temperature? Name one element of the third period which burns in chlorine with a coloured fl ame. Aluminium chloride may be produced by passing a stream of chlorine over heated aluminium powder in a long hard-glass tube. State two observations you could make during this reaction. and Write a balanced equation, with state symbols, for this reaction of aluminium with chlorine. No chloride of argon has ever been produced. Suggest a reason for this. When chlorides of the elements of the third period are added to water, some simply dissolve while others can be seen to react with the water. Complete the table below, stating how the chlorides of Na, Al, and Si behave when mixed with water. In the fi rst column use only the terms ‘dissolve’ or ‘react’. element Does the chloride dissolve or react? approximate pH of the resulting solution Na Al Si What type of reaction takes place between a chloride and water? Sulfur forms the compound S4N4 with nitrogen. The structure of S4N4 is shown below. Assume all bonds shown are single bonds. S S S S N N N N a b Determine the number of lone pairs of electrons around a nitrogen atom and a sulfur atom in S4N4. nitrogen atom sulfur atom Which bond angle, a or b, in the S4N4 molecule will be smaller? Explain your answer.
9701_s12_qp_22
THEORY
2012
Paper 2, Variant 2
View
Although the actual size of an atom cannot be measured exactly, it is possible to measure the distance between the nuclei of two atoms. For example, the ‘covalent radius’ of the Cl atom is assumed to be half of the distance between the nuclei in a Cl 2 molecule. Similarly, the ‘metallic radius’ is half of the distance between two metal atoms in the crystal lattice of a metal. These two types of radius are generally known as ‘atomic radii’. The table below contains the resulting atomic radii for the elements of period three of the Periodic Table, Na to Cl. element Na Mg Al Si P S Cl atomic radius / nm 0.186 0.160 0.143 0.117 0.110 0.104 0.099 Explain qualitatively this variation in atomic radius. Suggest why it is not possible to use the same type of measurement for argon, Ar. Use the Data Booklet to complete the following table of radii of the cations and anions formed by some of the period three elements. radius of cation / nm radius of anion / nm Na+ Mg2+ Al 3+ P3– S2– Cl – Explain the differences in size between the cations and the corresponding atoms. Explain the differences in size between the anions and the corresponding atoms. Each of the elements Na to Cl forms at least one oxide. Na2O is an ionic oxide, SO2 is a covalent oxide. Both oxides react with water. Write an equation for the reaction of each of these oxides with water. Na2O SO2 What is the pH of the resulting solution in each case? Na2O SO2 Write an equation for the reaction that occurs between the products of your reactions in .
9701_s12_qp_23
THEORY
2012
Paper 2, Variant 3
View
This question refers to the elements in the section of the Periodic Table shown below. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca transition elements Ga Ge As Se Br Kr From this list of elements, identify in each case one element that has the property described. Give the symbol of the element. An element that fl oats on cold water and reacts readily with it. An element that forms an oxide that is a reducing agent. The element that has the smallest fi rst ionisation energy. The element which has a giant molecular structure and forms an oxide which has a simple molecular structure. The element in Period 3 (Na to Ar) that has the smallest anion. The element in Period 3 (Na to Ar) which forms a chloride with a low melting point and an oxide with a very high melting point. Use the elements in Period 3 (Na to Ar) in the section of the Periodic Table opposite to identify the oxidereferred to below. In each case, give the formula of the oxide. An oxide which when placed in water for a long time has no reaction with it. An oxide which dissolves readily in water to give a strongly alkaline solution. Two acidic oxides formed by the same element. and An oxide which is amphoteric. Fluorine reacts with other elements in Group VII to form a number of different compounds. Two such compounds and their boiling points are given in the table. compound Cl F3 BrF3 boiling point / °C The two molecules have similar electronic confi gurations. Showing outer electrons only, draw a 'dot-and-cross' diagram of the bonding in Cl F3. The two molecules have the same shape. Suggest why the boiling points are signifi cantly different.
9701_s13_qp_21
THEORY
2013
Paper 2, Variant 1
View
This question refers to the elements in the section of the Periodic Table shown below. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca transition elements Ga Ge As Se Br Kr From this list of elements, identify in each case one element that has the property described. Give the symbol of the element. An element that when placed in cold water sinks and reacts readily. An element whose molecules contain π bonding. An element that forms a gaseous toxic oxide. The element which has a giant molecular structure and forms an oxide which also has a giant molecular structure. An element that forms a covalent chloride which dissolves in water to give a conducting solution. The element in Period 3 (Na to Ar) with the greatest electrical conductivity. Some of the elements in Period 3 (Na to Ar) burn with a coloured fl ame when heated in oxygen or chlorine. Give the symbol of one such element, the formula of the oxide formed, and state the fl ame colour that would be seen. symbol of element formula of oxide fl ame colour For the element you have used in , give the formula of the chloride formed, and state the pH of the solution produced when this chloride is shaken with water. formula of chloride pH of solution Chlorine reacts with both bromine and iodine to form BrCl and ICl respectively. The melting points of chlorine and the two chlorides are shown in the table. substance Cl 2 BrCl ICl m.p. / °C –101 –66 Showing outer electrons only draw a 'dot-and-cross' diagram of the bonding in ICl . Suggest why the melting points increase from Cl 2 to ICl . Suggest which of these three molecules has the largest permanent dipole. Explain your answer.
9701_s13_qp_22
THEORY
2013
Paper 2, Variant 2
View
This question refers to the elements in the section of the Periodic Table shown below. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca transition elements Ga Ge As Se Br Kr From this list of elements, identify in each case one element that has the property described. Give the symbol of the element. An element that has molecules which consist of single atoms. An element that has a molecule which contains exactly four atoms. The element that is a liquid at room temperature and pressure. The element in Period 3 (Na to Ar) that has the largest atomic radius. The element in Period 3 (Na to Ar) that has the highest melting point. The element in Period 3 (Na to Ar) that forms the largest anion. An element that reacts with water to give a solution that can behave as an oxidising agent. The formulae and melting points of some of the oxides of the elements in Period 3, Na to Cl, are given in the table. formula of oxide Na2O MgO Al 2O3 SiO2 P4O6 SO2 Cl 2O7 m.p. / °C –73 –92 Give the formulae of two of these oxides that have simple molecular structures. and Give the formula of one of these oxides that will give no reaction with water when placed in it for a long time. Give the formula of the product formed when MgO is reacted with SO2. The melting points of the elements Si to Cl are given in the table. element Si P S Cl m.p. / °C –102 Explain why the melting point of Si is very much greater than those of the other three elements. Suggest why the melting points of the other three elements are in the order S > P > Cl.
9701_s13_qp_23
THEORY
2013
Paper 2, Variant 3
View
Questions Discovered
224