With the STUDY NOTES you can revise the key concepts of each unit and check your progress. C O N C E P T M A P > Copy and complete the concept map. Boyle–Mariotte law when the … is constant, the product of the … the gas exerts and the volume it occupies remains constant the ideal gas equation of … KINETIC THEORY OF GASES GAS LAWS GAS EQUATIONS the general ideal gas equation p1 · V1 T1 = p2 · V2 T2 components concentration solute: it is in the … proportion … : it is in the highest proportion gases are made up of small … moving in a straight line the gas occupies the whole volume of the … there are no bonding … between the particles in a gas the pressure exerted is a measure of the number of … the temperature is proportional to the … of the particles Charles' law … when the … is constant, the quotient of the pressure the gas exerts and its absolute … remains constant when the … is constant, the quotient of the … of the gas and its absolute temperature remains constant p · … = n · R · T relates the p, V and … of a gas in two states relates the p, … and T of a gas and the moles (n) percentage by mass: % msolute = mass of solute mass of solution · 100 percentage by … : % Vsolute = volume of solute volume of solution · 100 concentration by … : Csolute = mass of solute volume of solution · 100 molarity: … = nsolute Lsolution SOLUTIONS 7 1 26 TA B L E . Copy and complete the table in your notebook. Atom Z A Protons Electrons Neutrons C 6 … … … 6 O … 16 8 … … F 9 19 … … … 27 D R AW I N G . In your notebook, match each atomic model to its name: Rutherford's model Quantum mechanical model Bohr's model Thomson's model 28 S U M M A R Y. In your notebook, match each sentence to the atomic model it relates to: Rutherford's model Quantum-mechanical model Bohr's model Thomson's model A. The atom is a positively charged mass with electrons scattered throughout it. B. Electrons are distributed in energy layers or levels. C. The gold foil experiment showed this model was wrong. D. This model explains why atoms produce line spectra. E. It describes an atom with a very small nucleus and lots of empty space between the electrons and the nucleus. F. This model explains all the lines in atomic spectra. G. It does not explain why the electrons do not end up falling into the nucleus. 29 TA B L E . In your notebook, draw two tables similar to the one below. Complete the information about the different particles in SI units and on the atomic scale. Proton Electron Neutron Mass … … … Charge … … … 30 V O C A B U L A R Y. Define these terms: a) Orbital b) Electronic configuration c) Ion d) Metallic character 31 S U M M A R Y. For each of the orbitals s, p, d and f, complete the sentences below in your notebook: a) In layer 2, there are … and … type orbitals. b) In each layer, there is one orbital of type … . 32 D R AW I N G . In your notebook, match each drawing to the type of orbital it represents. s p d f 33 S U M M A R Y. In your notebook, complete each sentence and indicate which principle it relates to: a) An atom cannot contain two … in the same state. b) Electrons occupy the … energy orbital available. c) The most stable electronic configuration is the one with the most electrons with the same … . The aufbau's principle Pauli's principle Hund's rule o r g a n i s e yo u r i d e a s Particles of an atom S O LV E D P R O B L E M 3 Calculate the mass of a proton and the mass of an electron in atomic units. Write down the relationship between the units. For the proton: mp = 1 67 10 1 66 10 27 27 . . ⋅ ⋅ ⋅ − − kg 1u kg » 1 u For the electron: me = 9.11 kg 1u 1.66 kg ⋅ ⋅ ⋅ = − − 10 10 31 27 5.49 10 u 4 ⋅ − 34 Indicate the number of protons, neutrons and electrons in each of these atoms: a) 16 8O c) 14 7N e) 4 2He g) 238 92U b) 14 6C d) 12 6C f ) 37 17Cℓ h) 197 79Au Atomic models 35 Review the gold foil experiment and explain whether these conclusions can be reached: a) Atoms are indivisible particles. b) Electrons are arranged in layers. c) Most of an atom is empty. 36 These sentences refer to Bohr's atomic model. Explain which one is correct: a) Protons orbit the nucleus without emitting energy. b) Electrons orbit the nucleus in specific orbits. c) Neutrons orbit the nucleus at any distance. 37 These sentences refer to the quantum-mechanical model. Explain if they are correct: a) Each electron spins around the nucleus in an orbit. b) In the first level, there are no p orbitals. c) In the second level, there are five d orbitals. d) 2p orbitals have less energy than 3p orbitals. 38 Indicate in your notebook whether there are differences in size and shape between these pairs of orbitals. a) 2s and 3p b) 2s and 5s c) 3d and 4d d) 2p and 3d 39 Do drawings to compare each of these pairs of orbitals: a) 1s and 2s b) 1s and 4s c) 2p and 3p d) 2s and 2p 40 Observe the electronic configuration of a phosphorus atom below and answer: 1s 2p 2s 3s 3p a) What does the electronic configuration of an atom represent? Write the electronic configuration of phosphorus using only letters and numbers. b) What three principles determine the electronic configuration of an atom? S O LV E D P R O B L E M 4 Write down the electronic configuration of cobalt. Find the atomic number of cobalt, Co, in the periodic table. Z = 27, each atom has 27 electrons. Use Möller's diagram and place 2 electrons in each orbital until you reach the total: 1s2 2s2 2p6 3s2 3p6 4s2 3d7 Remember to follow the three principles. Energy level Configuration Interpretation 1 1s2 It has 2 electrons in the 1s orbital. 2 2s2 2p6 It has 2 electrons in the 2s orbital. It has 2 electrons in each of the three 2p orbitals. 3 3s2 3p6 It has 2 electrons in the 3s orbital. It has 2 electrons in each of the 3p orbitals. 3 and 4 4s2 3d7 It has 2 electrons in the 4s orbital. The 4s orbital fills up before the 3d orbital. It has 7 electrons in the five 3d orbitals. According to Hund's rule of maximum multiplicity, first one electron occupies each d orbital and then they gradually fill up. c h e c k yo u r p r o g r e s s 2 a) c) b) d) a) c) b) d) e) f ) Use the STUDY NOTES to review the content of this unit. 55 54 Carbon nanotubes There are many applications that can obtain significant benefits from incorporating carbon nanotubes. For example, in fuel cells, nanotube-reinforced composites, field emitters in f lat screens, biological and chemical sensors to detect pollutants, and the release of drugs and medicines into the body. In general , sectors such as electronics, materials, sensors, biotechnology, chemistr y, energy, mechanics, scientific instrumentation and photonics could gain an advantage by introducing carbon nanotubes into many of their products. [...] In both cases, their main characteristic, which is responsible for many of their exceptional properties, is that they have a very high length-to-diameter ratio. Their diameter is in nanometres and their length can vary from a few micrometres to millimetres, and even a few centimetres. meetthings.com (Adapted) Single-walled carbon nanotubes (SWCNT) are composed of carbon atoms arranged in a hexagonal network and forming a cylinder. Their structure is the same as the structure that would be obtained by rolling up a sheet of graphite. They can be closed at the ends by half spheres of fullerene, or they can be open . Multi-walled carbon nanotubes (MWCNT) have a structure similar to a concentric arrangement of several SWCNTs with dif ferent diameters. > What type of bond joins carbon atoms together in nanotubes? Explain your answer. > Do you think nanotubes of iron could be made? Why? Carbon nanotubes are similar to small graphite sheets rolled into cylinders, with diameters measured in nanometres and lengths in micrometres. 14 FINAL ACTIVITIES 5 Study the information and apply your essential knowledge to different contexts and situations. Do the activities in the ORGANISE YOUR IDEAS and CHECK YOUR PROGRESS sections. Critical thinking. Analyse a news article and answer the questions that will help you to think about and show your reasoning. Make connections between Physics and Chemistry and other subject areas to help you understand the world you live in. Complete the challenge and tell other people what you have achieved. Share the results with the people around you. In this way, you are contributing to the construction of a better world for everyone. 55 The label on a bottle of perfume indicates that it is 80 % alcohol by volume. Calculate the amount of alcohol needed to prepare the 280 mL of perfume in the bottle. 56 Some "non-alcoholic" beers can contain up to 1 % alcohol. In a half-litre bottle of this type of beer, how much alcohol will there be? 57 C H E M I S T R Y A N D C O O K I N G Spherification is a commonly seen molecular cooking technique. It was popularised by chef Ferrán Adrià, although it has been known since 1946. It consists of enclosing a liquid inside a semi-solid membrane. To achieve this, a substance called sodium alginate must be added to the food. Drops of this mixture are then added to a bath of calcium chloride dissolved in water. After a few seconds, balls that resemble caviar can be collected. One of the keys to success is to be precise with the concentrations. You have to add 10 g of calcium chloride per litre of water. a) What is the molar concentration of the calcium chloride solution? b) How much calcium chloride do you need to prepare 100 cm3 of solution? S O LV E D P R O B L E M 1 3 Sodium sulphide (Na2S) is a water-soluble substance used as a bleach in the textile industry. a) How much Na2S do you need to prepare 500 mL of 1.5 M solution? b) What is the concentration of the sodium ion (Na+) in that solution? a) Calculate the amount of solute you need to prepare that amount of solution. M n V L s = → ( ) substitute the data: ns = M × V (L) = 1.5 M × 0.5 L = 0.75 mol To know the equivalent mass to these moles of solute, you must calculate their molar mass (M). M (Na2S) = 23 × 2 + 32.06 = 78.06 g/mol 0 75 1 . mol mol 78.06 g of Na S of Na S of Na S 2 2 2 ⋅ =58.55 g of Na S 2 b) When dissolved in water, Na2S separates into ions: Na2S ® 2 Na + + S2– Each mol of Na2S gives 2 mol of Na +. Therefore: The concentration of Na+ in the solution is: 2 × 1.5 M = 3 M 58 We prepare a solution by dissolving 15 mL of 1.5 M Na2S in water until it reaches 100 mL. What is the concentration of the new solution? 59 The solubility of some substances in water varies greatly with temperature. The graph shows the maximum amount of potassium nitrate (KNO3) that can be dissolved in 100 g of water at different temperatures. Solubility (g of solute/100 g of water) 20 30 50 60 70 80 90 40 100 200 180 160 140 120 100 80 60 40 20 0 T (°C) a) Read on the graph the solubility of KNO3 in water at 75 ºC. Express it as a percentage by mass. b) Determine whether we can prepare a solution of 30 % KNO3 in water at 45 ºC. c h e c k yo u r p r o g r e s s 32 41 Write the electronic configuration of the elements Ce, Xe, W and Pb in your notebook and interpret it. 42 Read the news article and answer in your notebook. A mother from San Diego wins the Nobel Prize This was the headline in a local newspaper announcing her award in 1963. Sixty years after Marie Curie won the Nobel Prize in Physics, the German physicist Maria Goeppert Mayer won the prize for her model that explained the nucleus of atoms: inside the nucleus, protons and neutrons are arranged in layers, according to their energy level . Her expertise in mathematics led her to make this discovery, which had an important impact on nuclear physics. Goeppert shone in a field that was traditionally dominated by men. Her recognition came after a long scientific career "on loan", in which she spent many years working without pay. bbvaopenmind .com (Adapted) a) Review the history of the atom. Find the names of the people who devised models to explain it. b) What other subjects played a role in Goeppert's discovery? Why was her model influential? c) Think about the headline in the local newspaper. Do you think it is appropriate? Why? Write a more appropriate headline for this news article. S O LV E D P R O B L E M 5 Write the electronic configuration of these atoms and ions. What do they have in common? Atom/ Ion No. of protons No. of electrons Electronic configuration 20 10Ne 10 10 1s 2 2s2 2p6 19 9F-1 9 10 1s2 2s2 2p6 24 12Mg2+ 12 10 1s2 2s2 2p6 They all have the same number of electrons. Chemical species (atoms or ions) that have the same electron configuration are called isoelectronic. 43 In your notebook, complete a similar table to the one in the previous example with the electronic configuration of Rb1+, Cℓ1-, Ca2+ and Se2-. Which noble gas has the same configuration as each of them? The periodic table of elements 44 Make a table in your notebook with the columns below. Complete the information for the elements Ne, F, O, I, Be, B and Cu. Element Z Electronic configuration Group Period Metal/ nonmetal Ne ... ... ... ... ... 45 The electronic configurations of different elements are: A: 1s2 2s1 C: 1s2 2s22p6 B: 1s2 2s22p5 D: 1s2 2s22p6 3s1 Correct the errors in these statements in your notebook: a) A is a nonmetal from group 1 and period 2. b) A and D belong to the same period. c) B and C are nonmetals. d) D is a metal from group 3 and period 1. Periodic properties of elements 46 Order the atoms from the smallest to the largest size: a) Cs, Li, Na c) P, N, As b) C, Li, Ne d) Mg, Ar, Na c h e c k yo u r p r o g r e s s 47 C H E M I S T R Y A N D M E D I C I N E . Chemical elements have diverse applications. Some are used as contrast agents to diagnose diseases in imaging techniques. For example, gadolinium is used in MRI (magnetic resonance imaging ) and the f luorine-18 isotope is used in PET (positron emission tomography). The element binds to proteins in tumour cells and causes a bright signal to be emitted that makes it easier to identify the tumour. Others are known poisons, such as mercur y and thallium. They are mentioned in classic works of literature. The Mad Hatter in Lewis Carroll 's Alice in Wonderland was poisoned by mercur y vapour. In The Pale Horse, Agatha Christie describes thallium as the perfect poison , as it is dif ficult to identify. dciencia .es (Adapted) 56 S O LV E D P R O B L E M 1 4 A 20 % glucose infusion is a solution of sugar in water with a density of 1.15 g/cm3. We want to prepare half a litre of 20 % glucose infusion. Calculate the amount of sugar needed. Solution: 20 % glucose infusion d = 1.15 g/cm3 V = 1500 mL Solute: sugar Solvent: water Using the density of the solution, calculate the mass equivalent to 500 mL: d m v m d V = → = ⋅ = ⋅ = 1.15 g 500 575 g mL mL Use the richness of sugar in the glucose infusion as a conversion factor: 575 20 10 g of infusion g of sugar g of infusion ⋅ = 115 g of sugar 60 To prepare half a litre of a solution of sodium chloride (NaCℓ) in water at 5 % by mass, how much sodium chloride will you need? Data: dsolution = 1.05 g/cm3. 61 We prepare a solution by mixing 20 g of sodium hydroxide in 200 mL of water. The density of the solution is 113 g/mL. Calculate the concentration in percentage by mass, in g/L, and molarity (M). 1 62 Analyse the news article. What exactly i s homeopathy? Homeopathy is based on a doctrine developed by the German physician Samuel Hahnemann at the end of the 18th centur y. It is based on the principle that " like cures like". According to it, the same substance that causes symptoms of a disease must be used to cure it, diluted in water in infinitesimal proportions. For example, caf feine wakes us up, but if taken in tiny proportions it does the opposite: it makes us sleepy. A homeopathic preparation for sleeping can be obtained by mixing one part of caf feine with 99 parts of water. It is shaken and the solution is mixed with another 99 parts of water. And so on . These preparations are usually taken in the form of sucrose and water tablets. Sometimes, no traces of the active ingredient to be administered remain in the tablet. The scientific evidence against the ef fectiveness of homeopathy is irrefutable. 13 years ago, the prestigious medical journal The Lancet ended the debate in an editorial entitled The end of homeopathy. elpais.com (Adapted) a) Imagine that you dissolve 1 g of glucose (C6H12O6) in water until it reaches 100 mL. What is its molarity? How many moles of glucose does 1 mL of this solution contain? b) Now add water to that 1 mL of solution until you have a final volume of 100 mL. What is the molarity of the glucose solution now? c) Use the results of the above calculations to prove that homeopathy is pseudoscience. Write a scientific report, applying the scientific method It is time to write the report for one of your scientific studies. Present it in the form of written text or as the script of an audiovisual production. You can start with a scientific problem from this unit or look for another one. Follow the scientific method, from observing to communicating the results. Remember that science has an important social responsibility. In addition to publishing in a journal, you should write an article to inform the general public. It is a good idea to include drawings or diagrams that help people to understand what you have studied and its consequences. While you were creating your report, you learnt the stages of the scientific method and applied them to the study of gases and solutions. W E L L D O N E ! CHALLENGE 33 In addition, there is helpful support material available: A FORMULATION ANNEX at the end of the book will help you to understand and practise chemical nomenclature with activities. A notebook with INNOVATIONS IN SCIENCE helps you to understand the importance of science in our society. THE CHALLENGE 6 2. Binary compounds Annex 1 Binar y compounds resu lt f rom the combinat ion of atoms of t wo chemica l elements. One w i l l have a posit ive ox idat ion number (the electroposit ive element) and the other w i l l have a negat ive ox idat ion number (the electronegat ive element). 2.1. Naming binary compounds Look at how the name of a bina r y compound is formed in t wo d i f ferent ways, using composit iona l nomenclatu re. 2.2. Writing the formula of a binary compound Look at how the formu la of a chemica l compound is formed f rom its name in composit iona l nomenclatu re: Prefixes Dia luminium tr isu lphide AℓS Wr ite the sy mbol of each element in the cor rect order. 1 AℓS Wr ite the sy mbol for each element . The one end ing in –ide w i l l be on the r ight in the formu la . 1 Aℓ2S3 Add the number cor respond ing to the pref i x of each element as a subscr ipt . In th is case, di, 2 for Aℓ and t ri, 3 , for S. 2 Aℓ S Locate the ox idat ion number of the elements in the table: Aℓ, electroposit ive element . Ox idat ion number : +3 S, electronegat ive element . Ox idat ion number : -2 2 Aℓ m Sn m ? (+3) + n ? (-2) = 0 m = 2 n = 3 Aℓ2S3 The sum of the ox idat ion numbers of a l l the elements must be zero for the compound to be neutra l . Find the sma l lest possible subscr ipts to simpl i f y the formu la as much as possible. For example, Aℓ4S6 is a lso va l id , but it shou ld be simpl i f ied . 3 Oxidation numbers A luminium su lphide S O LV E D P R O B L E M 1 Formula Prefixes Oxidation numbers AℓBr3 Aluminium tribromide Aluminium bromide CuCℓ2 Copper dichloride Copper(II) chloride A C T I V I T I E S 1 Name in your notebook: a) PbCℓ2 d) Cr2S3 b) AℓF3 e) Na3N c) BaI2 f ) K2S A C T I V I T I E S 2 Write the formula for: a) Barium chloride b) Tin tetraiodide c) Nitrogen trifluoride d) Mercury dichloride e) Phosphorus pentachloride f ) Iron(III) sulphide g) Cobalt(II) bromide h) Aluminium nitride S O LV E D P R O B L E M 2 Write the formula for these compounds. a) Barium dichloride b) Iron(III) iodide a) On the right, write the symbol of the element ending in -ide: chlorine. Add the subscript, 2, corresponding to the numerical prefix of chlorine, di: BaCℓ2 b) On the right, write the symbol of the element ending in -ide: iodine. To the iodine symbol, add the subscript indicating the oxidation number of iron, which is given by the Roman numeral: FeI3 Look up the ox idat ion number of the electroposit ive element in the table. Wr ite it in Roman numera ls inside brackets a f ter the posit ive element's name, w ithout leav ing a space. I f the element on ly has one ox idat ion number, it is not added to the name. dialuminium trisulphide sulphur tetrachloride aluminium sulphide sulphur(IV) chloride The name of each element is preceded by a pref i x that ind icates the number of atoms of th is element in the formu la : mono, for one. The pref i x mono can be omit ted i f there is no conf usion. di, for t wo. t ri, for three. tet ra, for fou r. penta, for f ive. hexa, for si x , etc. name of the element on the left + name of the element on the right + -ide Using prefixes Using oxidation numbers Look at these examples: Note that S is named after its Latin origin, sulphur. Aℓ only has one oxidation number, so it is not added. element acting as electronegative element acting as electropositive The negative oxidation number of Cℓ is -1. For the compound to be neutral, S must act with its oxidation number +4: +4 + (-1) ? 4 = 0 Element on the right: sulphide Element on the right: chloride Element on the left: aluminium Element on the left: sulphur Aℓ2S3 SCℓ4 The elements combine in a propor t ion that resu lts in a neutra l compound. That is, the sum of the oxidation numbers of all the elements in the formu la must be zero. +3 -2 +3 -2 293 292 ES0000000137418 183391_ANEXOS_115340.indd 292-293 18/7/22 13:36
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