molecules 1 and molecules 2 - lekolar

Experiment Description/Manual for the Science Kit

Molecules 1 andMolecules 2

Molecules 1 and Molecules 2

2

Science box Molecules 1 Order no. 18474

contains the basic elements for the assembly of atomic models of alphatic compounds.

Science kit Molecules 3 Order no. 36685

contains each 5 boxes Molecules 1 and Molecules 2Teacher´s manual Molecules

Science box Molecules 2 Order no. 31810

only to be used together with the box Molecules 1, to build up organic compounds.

Science kit Molecules 1

31764


42880


36685


contains 10 boxes Molecules 1Teacher´s manual Molecules


contains 10 boxes Molecules 2Teacher´s manual Molecules


3

Science Boxes

Molecules 1 and Molecules 2Contents

List of components...............................................................................................4

Table of components ...........................................................................................5

General Instructions ............................................................................................6

1. Notes on ball-and-rod models ..................................................................6

2. Applications of the Molecules 1 and Molecules 2 science boxes ..............6

3. Representing compounds with the Molecules 1 and Molecules 2 science boxes .............................................6

4. Teaching Notes ..........................................................................................8

5. A selection of important compounds ........................................................8

5.1 Alkanes .......................................................................................................8

5.2 Alkenes (olefins) ..........................................................................................8

5.3 Alkines ........................................................................................................8

5.4 Halogen derivatives of the alkanes ...............................................................8

5.5 Alkanoles (alcohols) ....................................................................................8

5.6 Alkanales (aldehydes) ..................................................................................9

5.7 Formation of high-molecular weight plastic Conversion of ethylene into polyethylene ....................................................9

5.8 Amino acids, proteins ..................................................................................9

5.9 Molecules of some elements .....................................................................10

5.10 Carbohydrates ..........................................................................................10

5.11 Carboxylic acids ........................................................................................12

5.12 Fat synthesis from oleic acid, butyric acid, stearic acid and glycerol ............12

5.13 Fat saponification ......................................................................................13

5.14 Synthetic detergents..................................................................................13

5.15 Aromatic hydrocarbons .............................................................................14

5.16 Condensed aromatic rings ........................................................................14

5.17 Benzene ring substitution ..........................................................................14

5.18 Dyes .........................................................................................................15

5.19 Drugs .......................................................................................................15

© 2008 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.Hint 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.


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List of components

Illustr. no. Qty. Description Order no.

Science Box Molecules 1, containing ........................................... 18474

1 60 Connecting rods, grey .................................................................. 18547 2 25 Hydrogen (H), monovalent, white ................................................. 18490 3 15 Oxygen (O), bivalent, red ............................................................. 18512 4 5 Chlorine (Cl), monovalent, green .................................................. 18504 5 5 Nitrogen (N), trivalent, blue .......................................................... 18520 6 14 Carbon (C), quadrivalent, black .................................................... 18539

Science Box Molecules 2, containing ........................................... 31810

7 80 Connecting rods, grey .................................................................. 18547 8 4 Universal building blocks, grey ...................................................... 39358 9 3 Benzene rings, black ..................................................................... 39340 10 8 Sulphur (S), bivalent, yellow .......................................................... 39315 11 4 Oxygen (O), bivalent, red ............................................................. 18512 12 4 Nitrogen (N), trivalent, blue .......................................................... 18520 13 8 Carbon (C), quadrivalent, black .................................................... 18539 14 4 Phosphorus (P), pentavalent, violet ............................................... 39323 15 4 Nitrogen (N), pentavalent, blue .................................................... 39331 1 4 Sulphur (S), hexavalent, yellow ..................................................... 39307

Enclosed printed material per Box:

– 1 Student’s manual “Molecules 1 and Molecules 2”................................................. 184746

Also available: Science Kit Molecules 1 (description on page 2) .......................... 31764 Science Kit Molecules 2 (description on page 2) .......................... 42880 Science Kit Molecules 3 (description on page 2) .......................... 36685

Enclosed printed material per Kit:

– 1 Teacher’s manual “Molecules 1 and Molecules 2”................................................. 366856 – 10 Student’s manuals “Molecules 1 and Molecules 2”................................................. 184746 – 1 Storage plan Molecules 1, DIN A3 .............................................3176436 or – 1 Storage plan Molecules 2, DIN A3 ........................................... 4288036 or – 1 Storage plan Molecules 3, DIN A3 ........................................... 3668536


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Science Box Molecules 1:

1 2 3 4 5 6

Science Box Molecules 2:

7 8 9 10 11 12 13 14 15 16

Table of components


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• 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. Hence, 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 O-Level chemistry lessons. However, in order to re-present 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

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 inter-national 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 arrange-ment 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;


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places high demands on students’ 3-dimensional visualisation skills. The following illustrations serve as information for teachers and show the correct con-figurations as well as one possible incorrect structure for the individual groups.

Sulphone group

(Tetrahedral bond orientation) (incorrect)

Nitro group

(Planar bond orientation, α = β) (incorrect; α ≠ β)

Phosphorus-oxygen group

(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

mechanisms, e.g. cracking process, breakdown of disaccharides and polysaccharides into monosac-charides, isomerism, substitution, addition, poly-merisation, 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.

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 = 0.000001 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, C4H10):

Length of the n-butane molecule model: 24 cm

Length of the n-butane molecule: X

5.6 cm : 0.15 nm = 24 cm : X

or

X : 24 cm = 0.15 nm : 5.6 cm

or, solving for X:

X = 24 cm . 0.15 nm ≈ 0.65 nm

Therefore, the length of the n-butane molecule is approximately 0.00000065 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 repre-sented 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.

ON O

NO2̄

5.6 cm

SO2̄ ¯

O

S

O

PO4̄ ¯¯

O

O P O

O


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10 Propanetriol (glycerol) CH2OH-CHOH-CH2OH

Please also see 5.12 Fat synthesis.

5. A selection of important compounds

5.1 Alkanes: empirical formula CnH2n+2

e.g. 1 Methane CH4 2 Ethane C2H6

3 Propane C3H8 4 n-Butane C4H10

5.3 Alkines: empirical formula CnH2n-2 5.2 Alkenes (olefins): empirical formula CnH2n

e.g. 5 Ethene (ethylene) C2H4e.g. 6 Ethine (acetylene) C2H2

5.4 Halogen derivatives of the alkanes:

e.g. 7 Monochlormethane (methylchloride) CH3Cl

5.5 Alkanoles (alcohols): empirical formula for a primary alcohol CnH2n+1OH

e.g. 8 Methanol (methyl alcohol) CH3OH

9 Ethanol (ethyl alcohol) C2H5OH

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. However, the manual provides a good basis to work from whenever rapid assembly of the models is important, for instance with more extensive models.

i-Butane C4H10


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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

14 Aminoacetic acid (glycine) 15 AlanineGlycine Glycine

Adenosine triphosphate (ATP)

Formation of a polypeptide from several simple amino acids

Material taken from each one box Molecules 1 and 2.

5.6 Alkanales (aldehydes): empirical formula: R-CHO

11 Methanal (formaldehyde) HCHO

12 Ethanal (acetaldehyde) CH3CHO


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5.9 Molecules of some elements

Carbon lattice in diamond

H2 S8

N2

5.10 Carbohydrates

Breakdown of cane sugar 19 to grape sugar 17 and fruit sugar 18 (hydrolysis)

C12H22O11 + H2O C6H12O6 + C6H12O6

CH2OH + H2O

H

HO

H

H

H

H

OH

OH

O

O

CH2OH

OH H

H HO

O HHOCH2

H

HO

H

H

H

H

OH

OH

O

OH

CH2OH

+

O

OH H

H HO

HHOCH2

HO CH2OH

Material taken from each one box Molecules 1 and 2.

18 Fructose17 Glucose


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5.10 Carbohydrates

Polysaccharides

e.g. 20 Starch (C6H10O5)n n = 50 . . . 5000

One starch molecule is formed by many grape sugar units on losing water (polycondensation):

Material taken from two Molecules 1 boxes.

The cellulose molecule 21 , like the starch molecule, is made up of numerous grape sugar groups. The number of C6H10O5-groups in a cellulose molecule is estimated to be about 10,000.


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Fragment R can be represented using a universal building block from the Molecules 2 box.

5.11 Carboxylic acids Examples:

26 Empirical formula of monocarboxylic acids: R-COOH

22 Methanoic acid (formic acid) HCOOH

23 Ethanoic acid (acetic acid) CH3COOH

24 Propanoic acid (propionic acid) CH3-CH2-COOH

25 Butanoic acid (butyric acid) CH3-(CH2)2-COOH

Material taken from four Molecules 1 boxes.5.12 Fat synthesis from oleic acid, butyric acid, stearic acid and 10 glycerol

Other spatial arrangements within the fat molecule are also possible.


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CH2OOCC17H35 CH2OH

3 NaOH + CHOOCC17H35 3 C17H35COO- Na+ + CHOH

CH2OOCC17H35 CH2OH

Material taken from one Molecules 1 box and two Molecules 2 boxes.5.13 Fat saponification

The fragment (labelled universal building block) has the formula –C17H35

5.14 Synthetic detergents

For all the following connections each one box Molecules 1 and 2 is required.

Fatty alcohol sulphates

Alkyl sulphonates

Alkylaryl sulphonates

R-O-SO3 Na+-

The group has the empirical formula CH3-(CH2)n-R-SO3 Na+-

R– -SO3 Na+-


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5.15 Aromatic hydrocarbons

Representation of benzene molecule with the components from the Molecules 1 box

Unlike the benzene molecule, the cyclohexane molecule is not planar.

27 Cyclohexane C6H12

Only Molecules 1 box required.

5.16 Condensed aromatic rings

Anthracene29 Naphthalene

5.17 Benzene ring substitution

28 Benzene

28 Benzene 30 Nitric acid 31 Nitrobenzene Water

Example of a cyclic, non-aromatic compound:


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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). However, 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

5.19 Drugs

Sulphathiazole 33 Penicillanic acid

32 Methyl orange (the Na+ ion is represented by a universal building block)

Experiment Description/Manual Science Kit „Molecules 1 and Molecules 2“Order no. 36685 6

© 2008 Cornelsen Experimenta, Berlin 10.00

Holzhauser Straße 76 Tel.: +49 30 435 902-0 eMail: [email protected] Berlin – Germany Fax: +49 30 435 902-22 Internet: www.corex.de

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