Experiment Description/Manual for the Science Kit. Molecules 1 and Molecules 2

Transcription

1 Experiment Description/Manual for the Science Kit Molecules 1 and Molecules 2

2 Science box Molecules 1 rder no contains the basic elements for the assembly of atomic models of alphatic compounds. Science box Molecules 2 rder no only to be used together with the box Molecules 1, to build up organic compounds. Science kit Molecules Science kit Molecules 1 rder no contains 10 boxes Molecules 1 Teacher s manual Molecules Science kit Molecules Science kit Molecules 2 rder no contains 10 boxes Molecules 2 Teacher s manual Molecules Science kit Molecules Science kit Molecules 3 rder no contains each 5 boxes Molecules 1 and Molecules 2 Teacher s manual Molecules 2

3 Science Boxes Molecules 1 and Molecules 2 Contents List of components...4 Table of components...5 General Instructions Notes on ball-and-rod models Applications of the Molecules 1 and Molecules 2 science boxes Representing compounds with the Molecules 1 and Molecules 2 science boxes Teaching Notes A selection of important compounds Alkanes Alkenes (olefins) Alkines alogen derivatives of the alkanes Alkanoles (alcohols) Alkanales (aldehydes) Formation of high-molecular weight plastic Conversion of ethylene into polyethylene Amino acids, proteins Molecules of some elements Carbohydrates Carboxylic acids Fat synthesis from oleic acid, butyric acid, stearic acid and glycerol Fat saponification Synthetic detergents Aromatic hydrocarbons Condensed aromatic rings Benzene ring substitution Dyes Drugs Cornelsen Experimenta, Berlin All rights reserved. The work and parts of it are protected by copyright. Every use for other than the legal cases requires the previous written agreement by Cornelsen Experimenta. int to 46, 52a UrhG: Neither the work or parts of it are allowed to be scanned, put into a network or otherwise to be made publicly available without such an agreement. This includes intranets of schools or other educational institutions. We assume no liability for damages which are caused by inappropriate usage of the equipment. 3

4 List of components Illustr. no. Qty. Description rder no. Science Box Molecules 1, containing Connecting rods, grey ydrogen (), monovalent, white xygen (), bivalent, red Chlorine (Cl), monovalent, green Nitrogen (N), trivalent, blue Carbon (C), quadrivalent, black Science Box Molecules 2, containing Connecting rods, grey Universal building blocks, grey Benzene rings, black Sulphur (S), bivalent, yellow xygen (), bivalent, red Nitrogen (N), trivalent, blue Carbon (C), quadrivalent, black Phosphorus (P), pentavalent, violet Nitrogen (N), pentavalent, blue Sulphur (S), hexavalent, yellow Enclosed printed material per Box: 1 Student s manual Molecules 1 and Molecules Also available: Science Kit Molecules 1 (description on page 2) Science Kit Molecules 2 (description on page 2) Science Kit Molecules 3 (description on page 2) Enclosed printed material per Kit: 1 Teacher s manual Molecules 1 and Molecules Student s manuals Molecules 1 and Molecules Storage plan Molecules 1, DIN A or 1 Storage plan Molecules 2, DIN A or 1 Storage plan Molecules 3, DIN A

5 Table of components Science Box Molecules 1: Science Box Molecules 2:

6 General Instructions The molecule models are assembled simply by linking up the models of the atoms using the connecting rods. The rods are flexible, so that they can also be used to show multiple bonds (double, triple). Models requiring a very large number of atoms can be assembled using components from more than one Molecule box. The models of the atoms have been designed to join up at the spatially correct angles. The colour coding of the different atoms follows international conventions. In addition, each atomic model bears the appropriate chemical symbol. After use, the individual components should be placed in the box as shown in the illustration on page 5 to facilitate checking whether all components are present. 1. Notes on ball-and-rod models Ball-and-rod models of molecules can be built with the science boxes Molecules 1 and Molecules 2. These models are particularly suitable for depicting the stoichiometric valency and the spatial arrangement of atom centres within a molecule, but do not accurately demonstrate the proportions of atomic shells or the differences between σ and π-bonds. Generally speaking, models only represent a few aspects of reality and therefore when using a model, the significance of all building blocks must be clear. The balls represent individual atom centres (the different dimensions of the atomic shells are not taken into account). Each vacant plug on a ball stands for a missing electron, and each connecting rod for a binding electron pair. With ball-and-rod models it is only possible to build molecules with covalent bonds (also molecules of elements) or ions, provided they are made up of molecules. Cations are represented by vacant plugs, and anions by connecting rods on plugs. The following cannot be represented by ball-and-rod models: ionic compounds which form ionic (polar) crystals, e.g. NaCl; compounds with hydrogen bridges, etc., e.g. polypeptide chains; mesomeric states of systems (though their resonating structure can be demonstrated) The example of the diamond lattice on page 8 shows a crystalline structure, though this is not a contradiction of the above. The bonds between the individual carbon atoms in diamond are covalent. Benzene plays a special role in chemistry lessons. ence, it was deemed appropriate to deviate from the ball-and-rod model for this single substance. For building aromatic hydrocarbons, the science box contains three special benzene building blocks to provide a more detailed insight into the spatial arrangement within the molecule. 2. Applications of the Molecules 1 and Molecules 2 science boxes The science box Molecules 1 generally suffices for -Level chemistry lessons. owever, in order to represent important organic compounds in schools offering advanced chemistry, science box Molecules 2 is generally also necessary (science box Molecules 2 can only be used in conjunction with science box Molecules 1). In this manual, those molecule models which go beyond the scope of the Molecules 1 kit are labelled accordingly. 3. Representing compounds with the Molecules 1 and Molecules 2 science boxes To keep the number of different building blocks to a minimum, the science boxes do not accurately portray the various bond angles. The atom models are designed such that students can dispense with instructions as to how the molecules are assembled. Nonetheless, the bond angles between the atom centres are portrayed as useful spatial approximations. Molecular structures can therefore be demonstrated clearly. Should assistance prove necessary during assembly, the models are illustrated in the teacher s manual in such a manner that they can be easily put together. The realistic model representation of the sulphone group, nitro group and phosphorus-oxygen group 6

7 places high demands on students 3-dimensional visualisation skills. The following illustrations serve as information for teachers and show the correct configurations as well as one possible incorrect structure for the individual groups. Sulphone group S S 2 mechanisms, e.g. cracking process, breakdown of disaccharides and polysaccharides into monosaccharides, isomerism, substitution, addition, polymerisation, polyaddition, polycondensation etc. Models are particularly indispensable when it comes to understanding isomerism, and in the hands of students, they enhance the results of the learning process. (Tetrahedral bond orientation) Nitro group N N 2 (incorrect) The models also show the differences with respect to the size and geometry of molecules, on which the properties of various substances depend (melting point, boiling point, stability etc.). The geometry of molecules can also be elucidated using the Gillespie and Nyholm theory (electron-pair repulsion model). The mean distance between the centres of adjacent atoms in a compound is approximately 0.15 nanometres (nm). (1 nm = 10-6 mm = mm) In the model, this distance is about 5.6 cm. From the length of a molecule model, the actual length of the molecule can be approximated. Example (n-butane, C 4 10 ): (Planar bond orientation, α = β) (incorrect; α β) Length of the n-butane molecule model: 24 cm Length of the n-butane molecule: X Phosphorus-oxygen group P P cm : 0.15 nm = 24 cm : X or X : 24 cm = 0.15 nm : 5.6 cm or, solving for X: X = 24 cm nm 0.65 nm 5.6 cm (Tetrahedral bond orientation) (incorrect) The colours used for the various atom types comply with international conventions. Furthermore, each atom model is embossed with the respective chemical symbol. In addition to greatly facilitating the derivation of empirical and structural formulas, the molecule models also make it possible to demonstrate and interpret numerous phenomena and reaction Therefore, the length of the n-butane molecule is approximately mm. The molecule models are built by simply linking the atom models with the connecting rods. Multiple bonds (double and triple bonds) can also be represented by means of the flexible connecting rods. Where appropriate, models consisting of a greater number of atoms can be assembled using the components from several boxes. 7

8 4. Teaching Notes Given below are examples of compounds for which science box molecular models can be assembled. In each case both the empirical and structural formulae are given, in many cases the model is also shown. If the aim of the lesson is to work with the models then determine the structural formulae and work out empirical or group formulae, it is advisable not to use the examples of the manual at first. owever, the manual provides a good basis to work from whenever rapid assembly of the models is important, for instance with more extensive models. 5. A selection of important compounds 5.1 Alkanes: empirical formula C n 2n+2 e.g. 1 Methane C 4 2 Ethane C 2 6 i-butane C Propane C n-butane C Alkenes (olefins): empirical formula C n 2n 5.3 Alkines: empirical formula C n 2n-2 e.g. 5 Ethene (ethylene) C 2 4 e.g. 6 Ethine (acetylene) C alogen derivatives of the alkanes: e.g. 7 Monochlormethane (methylchloride) C 3 Cl 5.5 Alkanoles (alcohols): empirical formula for a primary alcohol C n 2n+1 e.g. 8 Methanol (methyl alcohol) C 3 9 Ethanol (ethyl alcohol) C Propanetriol (glycerol) C 2 -C-C 2 Please also see 5.12 Fat synthesis. 8

9 5.6 Alkanales (aldehydes): empirical formula: R-C 11 Methanal (formaldehyde) C 12 Ethanal (acetaldehyde) C 3 C 5.7 Formation of high-molecular weight plastic 13 Conversion of ethylene into polyethylene: Ethylene Polyethylene 5.8 Amino acids, proteins e.g. Formation of a dipeptide 16 from two amino acids Formation of a polypeptide from several simple amino acids 14 Aminoacetic acid (glycine) Glycine 15 Alanine Glycine Adenosine triphosphate (ATP) Material taken from each one box Molecules 1 and 2. 9

10 5.9 Molecules of some elements Material taken from each one box Molecules 1 and 2. 2 S 8 Carbon lattice in diamond N Carbohydrates Breakdown of cane sugar 19 to grape sugar 17 and fruit sugar 18 (hydrolysis) C C C C 2 C 2 C C 2 + C 2 C 2 17 Glucose 18 Fructose 10

11 5.10 Carbohydrates Material taken from two Molecules 1 boxes. Polysaccharides e.g. 20 Starch (C ) n n = ne starch molecule is formed by many grape sugar units on losing water (polycondensation): The cellulose molecule 21, like the starch molecule, is made up of numerous grape sugar groups. The number of C groups in a cellulose molecule is estimated to be about 10,

12 5.11 Carboxylic acids Examples: 26 Empirical formula of monocarboxylic acids: R-C 22 Methanoic acid (formic acid) C 23 Ethanoic acid (acetic acid) C 3 C 24 Propanoic acid (propionic acid) C 3 -C 2 -C 25 Butanoic acid (butyric acid) C 3 -(C 2 ) 2 -C Fragment R can be represented using a universal building block from the Molecules 2 box Fat synthesis from oleic acid, butyric acid, stearic acid and 10 glycerol Material taken from four Molecules 1 boxes. ther spatial arrangements within the fat molecule are also possible. 12

13 5.13 Fat saponification Material taken from one Molecules 1 box and two Molecules 2 boxes. The fragment (labelled universal building block) has the formula C C 2 CC C 2 3 Na + CCC C C - Na + + C C 2 CC C 2 For all the following connections each one box Molecules 1 and 2 is required Synthetic detergents Fatty alcohol sulphates Alkylaryl sulphonates Alkyl sulphonates R--S - 3 Na + R -S - 3 Na + R-S - 3 Na + The group has the empirical formula C 3 -(C 2 ) n - 13

14 5.15 Aromatic hydrocarbons Example of a cyclic, non-aromatic compound: 28 Benzene Representation of benzene molecule with the components from the Molecules 1 box 27 Cyclohexane C 6 12 Unlike the benzene molecule, the cyclohexane molecule is not planar. nly Molecules 1 box required Condensed aromatic rings 29 Naphthalene Anthracene 5.17 Benzene ring substitution 28 Benzene 30 Nitric acid 31 Nitrobenzene Water 14

15 5.17 Benzene ring substitution 28 Benzene Sulphuric acid Benzene monosulfonic acid Water 5.18 Dyes In the given examples, the colouring is caused by delocalised electron systems within the molecules (mesomeric systems). owever, mesomeric systems are not distinguished as such in models constructed using the Molecules boxes, but are shown as groups of electron-pair bonds (see Chapter 1 of this manual). p-nitraniline 32 Methyl orange (the Na + ion is represented by a universal building block) 5.19 Drugs Sulphathiazole 33 Penicillanic acid 15

16 Experiment Description/Manual Science Kit Molecules 1 and Molecules 2 rder no olzhauser Straße 76 Tel.: info@corex.de Berlin Germany Fax: Internet: Cornelsen Experimenta, Berlin 10.00