Econ

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Contents

|PART I PLANET EARTH |
|Chapter 1 Fundamentals of chemistry | |
|The scientific method |1 |
|Kinetic theory of matter |2 |
|Chapter 2 The atmosphere | |
|A simple experiment to determine the percentage of oxygen in air |4 |
|Chapter 3 Oceans | |
|Folding filter paper in fluted form |6 |
|PART II MICROSCOPIC WORLD I |
|Chapter 5 Atomic structure | |
|Alchemy atomic symbols and Dalton’s atomic symbols |8 |
|What is an orbital? |9 |
|Discovery of electron, proton and neutron |12 |
|Chapter 7 Chemical bonding: ionic bonding | |
|Evidence of ions from electrolysis |16 |
|Chapter 9 Structures and properties of substances | |
|Hydration of sodium chloride |19 |
|Allotropy |20 |
|PART III METALS |
|Chapter 10 Occurrence and uses of metals | |
|Alloys |21 |
|Chapter 12 Reacting masses | |
|Combustion analysis of organic compounds |23 |

PART I PLANET EARTH

Chapter 1 Fundamentals of Chemistry

■ The scientific method To study chemistry, we should have some ideas of how scientists work. Scientists work by following the scientific method (Figure S1.1):

[pic] Figure S1.1 The scientific method.

1. Look for scientific facts by the observation of nature or experiments. (A scientific fact is an observation that is so consistently repeatable that there is no doubt about it.) 2. Compare and classify a large number of scientific facts. 3. Try to find patterns within a group of related scientific facts. (An important pattern is called a law.) 4. Try to think of a possible explanation for the pattern (or law). The suggested explanation is called a hypothesis. The hypothesis should enable scientists to make predictions. 5. Design new experiments to test the hypothesis. If the observation of nature or the predictions fail, the hypothesis is modified. 6. A well-tested and widely accepted hypothesis becomes a theory. 7. Predictions based on a theory are tested by further experiments. If a theory cannot always make correct predictions, it should be modified until it can. If this cannot be done, scientists have to look for a new theory. Thus, the process is in fact a never ending one. ■ Kinetic theory of matter It is shown by the Brownian movement experiment that particles are continually moving. Ideas about the movement of particles in matter are summarized in the kinetic theory of matter: 1. All matter is composed of tiny particles, with spaces between them. 2. (a) Particles are in constant, random motion and so have kinetic energy. (b) The average kinetic energy of particles in a substance increases with temperature.

Example S1.1
Explaining diffusion in terms of the kinetic theory of matter
A gas jar of air is inverted over a gas jar of brown nitrogen dioxide gas, with a glass plate separating them (Figure S1.2a). When the glass plate is removed, the brown gas gradually diffuses into the jar of air (Figure S1.2b). Explain this in terms of the kinetic theory of matter. (a) [pic] (b) [pic]
Figure S1.2 Diffusion of nitrogen dioxide gas into air.

Solution [pic] [pic] (a) (b)
According to the kinetic theory of matter, everything is made up of particles. Air is made up of tiny moving particles; nitrogen dioxide is also made up of tiny moving particles.
Air is colourless and nitrogen dioxide is reddish brown. After the glass plate is removed, it appears that the reddish brown gas spreads into the upper gas jar. In fact, the particles gradually become evenly mixed in the two gas jars.

Applying kinetic theory to different states of matter The kinetic theory of matter can be applied to the three states of matter ( solid, liquid and gas (Figure S1.3). In each case, the arrangement and movement of particles are different (Figure S1.4). [pic] Solid Liquid Gas Figure S1.4 The arrangement and movement of particles in solids, liquids and gases are different.

1. In solids Particles are tightly packed with little spaces among them. Therefore, a solid has a fixed volume and is almost incompressible. Particles in it have low kinetic energy and are arranged in a fixed pattern. Although they can vibrate about their fixed positions, they cannot move from one place to another. A solid therefore has a definite shape.

2. In liquids Particles are packed fairly close together, though not so close as in solids. Spaces between particles are still very little. Therefore, a liquid has a fixed volume and it is difficult to compress a liquid. Particles in it have higher kinetic energy than in solids. Because the particles can move freely, they are not arranged in a fixed pattern. A liquid therefore has no fixed shape of its own (Figure S1.5). [pic] Figure S1.5 A liquid has no fixed shape. It takes up whatever shape of the container.

3. In gases The particles are widely separated with a lot of empty space between them. Thus, it is easy to compress a gas. The particles have very high kinetic energy and move freely at great speeds. They spread into any available space, filling the whole container. The particles hit the inner wall of the container continually, exerting a force. The force on each unit area of the wall is called the gas pressure (Figure S1.6).

Chapter 2 The atmosphere

■ A simple experiment to determine the percentage of oxygen in air We can perform a simple experiment to find the percentage (by volume) of oxygen in air. Consider heating copper in air. Copper reacts with oxygen:

copper + oxygen ( copper(II) oxide reddish brown black

This reaction can be used to serve our purpose, in a set-up as shown in Figure S2.1. [pic]

Figure S2.1 A set-up used to determine the percentage (by volume) of oxygen in air.

1. Pack a hard-glass tube with copper turnings. 2. Connect the glass tube to two gas syringes A and B. 3. Syringe A contains 100 cm3 of air and syringe B has no air (Figure S2.1a). 4. (a) Heat the copper turnings strongly. (b) At the same time, push and pull the plungers several times, to pass air back and forth over the heated copper. (c) With no air in syringe B, take down the new volume reading in syringe A. 5. Repeat step 4 until the volume reading does not drop any further. 6. Let the set-up cool to room temperature. 7. Take down the final volume of ‘air’ left in syringe A.

Example S2.1 shows how the percentage (by volume) of oxygen can be worked out from the experimental results.

Example S2.1
Determining the percentage of oxygen in air
In an experiment to determine the percentage of oxygen in air (Figure S2.1), the copper turnings turned black. The results are as follows: Total volume of air in the syringes before heating = 100 cm3 Final volume of ‘air’ left in the syringes after heating and then cooling = 79 cm3
(a) Why should the set-up be allowed to cool to room temperature before the final volume reading is taken?
(b) How much oxygen (in cm3) was removed by the copper turnings?
(c) Calculate the percentage by volume of oxygen in air.

Solution
(a) Air expands on heating and this would affect the accuracy of the readings. Thus, volumes should be measured at the same temperature (room temperature).
(b) Volume of oxygen removed by the copper turnings = volume of air before heating – volume of air after heating and then cooling = 100 – 79 cm3 = 21 cm3
(c) Percentage by volume of oxygen in air = [pic] ( 100% = [pic] ( 100% = 21%

Chapter 3 Oceans

■ Folding filter paper in fluted form ‘Fluted’ filter paper is used when you wish to separate a liquid and a solid, keeping the liquid and discarding the solid. This arrangement of folds in the filter paper will allow the liquid to pass through it very quickly. It provides a lot of surface area for collecting the solid ‘impurity’.

To fold the filter paper in fluted form, we do the following: 1. Fold the large circle of filter paper in half, then in quarters. [pic] [pic] [pic]

2. Take the straight edge on one side and fold back to the centre fold (Figures 2a and 2b). Do the same on the other side. Open the ‘fan’ up with the centre fold going away from you (Figure 2c). [pic] [pic] [pic] (a) (b) (c) 3. Starting at one side, fold the straight edge up towards the first fold (Figure 3a). Fold back along the preformed fold and then fold again towards the centre fold (Figure 3b). [pic] [pic] (a) (b) 4. Continue folding back and forth until you get another smaller-sized fan. [pic] [pic] [pic]

5. Open the ‘fan’ and look for the two areas called the ‘boxes’. Pinch the paper to make another fold between the two folds in each box. Then invert the filter paper before you place it in the filter funnel. [pic] [pic] PART II MICROSCOPIC WORLD I

Chapter 5 Atomic structure

■ Alchemy atomic symbols and Dalton’s atomic symbols In 300 B.C.–A.D. 1500, many scientists focused on alchemy and had invented a set of symbols to represent different elements, as shown in Figure S5.1. [pic] [pic] [pic] Platinum Gold Silver [pic] [pic] [pic] Copper Iron Lead [pic] [pic] [pic] Magnesium Mercury Phosphorus

Figure S5.1 Some of the Alchemy symbols.

After that, John Dalton invented a set of symbols, some of which are shown in Figure S5.2. [pic] Figure S5.2 Some of the Dalton’s atomic symbols. A few of ‘Dalton’s elements’ are not elements at all.

John Dalton used the above symbols to represent different elements. However, they were not commonly used by chemists and were later replaced by a better system suggested by the Swedish chemist Berzelius in 1811. He introduced a simpler system of symbols based on letters instead of signs.

What is an orbital? Orbitals and orbits In the textbook, when we are talking about an atom, we usually describe it as electrons moving around a nucleus. This situation is just like planets moving around the Sun. The circular path of the electrons is called the orbit.

However, the situation is very different in reality. For example, if we could plot the locations of the electron of a hydrogen atom at different instants, the resultant pattern will look like that in Figure S5.3. You may find that the pattern looks quite different from that you have learnt from the textbook. The movement of an electron cannot be represented by an orbit. We can only describe the location of an electron in terms of the probability of finding it in a certain position. The term orbital or atomic orbital is used to represent a region within which there is a high probability of finding an electron (usually 90% of the time).

The atomic orbital can be represented by an electron cloud model. Figure S5.3 shows the electron cloud model of a hydrogen atom. The probability of finding an electron within a spherical space around the nucleus is about 90%. You may notice that further away from the nucleus, the electron density becomes smaller.

Do you know? In the past, many scientists had proposed their own ‘atomic models’. The evolution of atomic models can be briefly summarized in the figure below: [pic]

Classification of orbitals 1. s orbitals Figure S5.4 shows the 1s, 2s and 3s orbitals. The left one is the 1s orbital. The ‘1’ represents the fact that the orbital is in the first energy level. That means it is closest to the nucleus. The ‘s’ gives information on the shape of the orbital. All s orbitals are spherical in shape. The distribution of electron density in 2s and 3s orbitals is similar to that in the 1s orbital.

[pic] 1s 2s 3s Figure S5.4 The shapes of the s orbitals.

2. p orbitals Figure S5.5 shows the p orbitals. With different orientations, p orbitals can be further classified as px, py and pz orbitals. It should be noticed that the p orbitals are all dumb-bell shaped. [pic] 2px 2py 2pz Figure S5.5 The shapes and orientations of different p orbitals.

3. d orbitals Figure S5.6 shows the d orbitals. With different orientations, d orbitals can be further classified as dyz, dxz, dxy, dx2(y2 and dz2.

[pic] 3dyz 3dxz 3dxy 3dx2(y2 3dz2
Figure S5.6 The shapes and orientations of different d orbitals.

Table S5.1 shows the orbitals present in each energy level and the maximum number of electrons each energy level can accommodate. It should be noticed that: ← For the first energy level, there is only one type of orbital labelled as 1s. ← For the second energy level, there are two types of orbitals labelled as 2s and 2p. ← For the third energy level, there are three types of orbitals labelled as 3s, 3p and 3d. ← For the fourth energy level, there are four types of orbitals labelled as 4s, 4p, 4d and 4f.

|Energy level |Orbitals present |Maximum number of electrons accommodated |
|1 |s |2 |
|2 |s, p |8 |
|3 |s, p, d |18 |
|4 |s, p, d, f |32 |

Table S5.1 Orbitals present and maximum number of electrons accommodated in different energy levels.

Electronic configuration of an element As we have learnt before, the electronic configuration of fluorine is 2,7. You may now realize that for the first energy level, there are two electrons filling the s orbitals. For the second energy level, two electrons fill the s orbitals and the rest five electrons fill the p orbitals. The electrons in a fluorine atom are distributed among its 1s, 2s and 2p orbitals. The electronic configuration of fluorine can be represented as 1s22s22p5.

Discovery of electron, proton and neutron John Dalton suggested that atoms are tiny ‘solid’ spheres which could never be divided (Figure S5.7). This idea was first shown to be wrong when a particle smaller than the atom, called the electron, was discovered during a study of cathode rays by J.J. Thomson in 1897. [pic] Figure S5.7 Dalton’s model of an atom – the solid indivisible atom.

Discovery of electron Rays consisting of electrons (or cathode rays) are produced when a high voltage (above 5000 V) is put across two metal electrodes at very low gas pressure (about 0.0001 atmosphere) in a discharge tube.

Cathode rays can be detected by zinc sulphide screen, which emits visible light when hit by electrically charged particles. If a metal cross is placed in the path of the rays as in Figure S5.8, a sharp shadow is projected on the screen. This shows that cathode rays travel in straight lines.

[pic] Figure S5.8 A metal cross in the cathode ray tube obstructs cathode rays and casts a sharp shadow.

If the rays are made to pass between a pair of charged plates as in Figure S5.9, they will be deflected by the electric field. They move away from the negatively charged plate towards the positively charged plate. They can also be deflected by a magnetic field. Thus, cathode rays cannot be rays of light; they are in fact a stream of negatively charged particles.

[pic]

Figure S5.9 Cathode rays are attracted by the positively charged plate.

Thomson found that exactly the same particles (electrons) are produced irrespective of the gas present or the materials used to make the tube and the electrodes. Further experiments show that they are in fact a fundamental constituent of all atoms.

Discovery of proton An atom does not have an overall electric charge. It is said to be electrically neutral. Since electrons are negatively charged and are present in all atoms, there must be some positive charges present in atoms to maintain overall electrical neutrality. If all atoms contain positive and negative charges, then how are they arranged inside an atom?

Thomson suggested that an atom was like a ‘raisin pudding’ (Figure S5.10). In his view, the negatively charged electrons stick into a sphere of positive charges, just like raisins in a pudding. The mass and charge are distributed among the structure of the atom.

[pic] Figure S5.10 Thomson’s model of an atom.

Thomson’s idea about the atoms was put to test by Ernest Rutherford (Thomson’s student) and his research workers in 1911. In the Rutherford’s gold foil scattering experiment, small positively charged particles, called alpha particles, were shot at a very thin gold foil at high speed (Figure S5.11). Most of the alpha particles passed through the gold foil without changing direction or were only slightly deflected. But surprisingly, a few were deflected through large angles and a very few even rebounded back!

[pic]

Figure S5.11 Set-up for Rutherford’s gold foil scattering experiment.

The experimental results indicated that only a few alpha particles had hit a positively charged centre which is very small in size but very concentrated in mass. This finding could never be explained by using Thomson’s model. See Figure S5.10 again.

To explain the observed results, Rutherford proposed another model for the atom (Figure S5.12). He suggested that an atom consists of a central, minute nucleus where the mass and positive charges of the whole atom are concentrated. The negatively charged electrons occupy the remaining space in the atom, revolving around the nucleus.

[pic] Figure S5.12 Rutherford’s atomic model.

Look at Figure S5.13 and see how Rutherford’s atomic model explains the results of the Rutherford’s gold foil scattering experiment.

[pic] Figure S5.13 Explaining the results of Rutherford’s gold foil scattering experiment.

Rutherford and other scientists found that the positive charge of the nucleus was due to positively charged particles called protons. Each proton carries one unit of positive charge, exactly balancing the negative charge on one electron.

Discovery of neutron In the nucleus of a helium atom, there are two protons, but its mass is very nearly four times that of a hydrogen atom. To explain this, Rutherford suggested that the helium nucleus should also contain two uncharged particles. Each of these particles has the same mass as a proton.

In 1932, Chadwick, one of Rutherford’s collaborators, succeeded in detecting such a particle. It is called neutron.

Chapter 7 Chemical bonding: ionic bonding

■ Evidence of ions from electrolysis Electrolysis of molten lead(II) bromide Solid lead(II) bromide does not conduct electricity. However, molten lead(II) bromide conducts electricity. See Figure S7.1. Reddish brown bromine vapour is liberated at the anode (positive electrode in this case). A silvery grey substance (lead) is deposited at the cathode (negative electrode in this case). Molten lead(II) bromide is thus decomposed to the two elements lead and bromine. The whole process is called electrolysis (meaning ‘decomposition by electricity’).

[pic]

Figure S7.1 Electrolysis of molten lead(II) bromide.

When electricity is passed through molten lead(II) bromide, there is chemical decomposition. But why does molten lead(II) bromide conduct electricity, and why does the decomposition take place at the electrodes?

Molten lead(II) bromide conducts electricity. It must therefore consist of charged particles that are free to move. These particles are called ions. As shown in Figure S7.2, positively charged lead(II) ions move to the cathode (negative electrode in electrolysis). They gain electrons there to become lead. Negatively charged bromide ions move to the anode (positive electrode in electrolysis). They lose electrons there to become bromine. Thus, electric current is carried through molten lead(II) bromide by mobile (freely moving) ions. [pic] Figure S7.2 The movement of particles during electrolysis of molten lead(II) bromide.

Lead(II) bromide does not conduct electricity in the solid state. This is because ions in solids are not mobile (i.e. unable to move freely) due to strong attractions among ions. When solid lead(II) bromide is heated until it melts, the ions present become mobile. Therefore, molten lead(II) bromide conducts electricity.

Electrolysis of aqueous copper(II) chloride solution A simple set-up for investigating electrolysis of aqueous copper(II) chloride solution is shown in Figure S7.3.

[pic] Figure S7.3 Electrolysis of aqueous copper(II) chloride solution.

Aqueous copper(II) chloride solution conducts electricity. During electrolysis, copper(II) chloride is decomposed to form copper (reddish brown solid) at cathode and chlorine gas (with smell of swimming pool) at anode.

We can also explain the electrolysis of aqueous copper(II) chloride solution in terms of ions.

Electrolytes and ions Lead(II) bromide is a compound made up of a metal (lead) and a non-metal (bromine). Copper(II) chloride is a compound made up of a metal (copper) and a non-metal (chlorine). They do not conduct electricity in the solid state. However, they conduct electricity when melted (molten) or dissolved in water, with chemical decomposition. They are electrolytes. Most electrolytes are compounds made up of metals and non-metals.

Electrolysis experiments show that mobile, charged particles exist in molten and in aqueous electrolytes. These charged particles, called ions, are responsible for conduction of electricity in electrolytes.

Chapter 9 Structures and properties of substances

■ Hydration of sodium chloride Why is sodium chloride soluble in water? When sodium chloride is added to water, Na+ ions in the crystal are attracted by negative ends of polar water molecules; Cl( ions are attracted by positive ends of water molecules. The ions are thus ‘pulled away’ from the giant ionic structure and go into solution. See Figure S9.1.

[pic] Figure S9.1 Water dissolving the ionic solid sodium chloride.

In solution, each sodium ion has a number of water molecules attached to it; sodium ions are said to be hydrated. The same happens to the chloride ions. Hydrated sodium and chloride ions are represented by Na+(aq) and Cl((aq) respectively.

Some solid ionic compounds (e.g. barium sulphate) are insoluble in water. This is because the attraction between ions in the crystal is greater than that between the ions and water molecules.

Ionic solids are insoluble in non-polar solvents. This is because the non-polar molecules have little attraction for the ions. Therefore, the giant ionic structures do not break up.

■ Allotropy Different forms of an element in the same state, such as diamond and graphite, are called allotropes. The element is said to exhibit allotropy.

Allotropy is the existence of an element in more than one form in the same state. Allotropes always have different physical properties due to different structures, but they often have similar chemical properties. Other elements which show allotropy include phosphorus (e.g. yellow phosphorus and red phosphorus) and tin (e.g. white tin and grey tin).

Note that the term ‘polymorphism’ is different from ‘allotropy’. Polymorphism refers to the existence of an element or compound in more than one form in the same state, so it has a broader sense than allotropy. The different forms are called polymorphs. Zinc oxide is a compound exhibiting polymorphism. It is white in colour at room temperature, but becomes yellow when hot, owing to a change in crystal structure.

PART III METALS

Chapter 10 Occurrence and uses of metals

■ Alloys We have discussed the properties and uses of some common metals. The most common metal iron is seldom used in pure form. Most of it is used to make steel, which is an alloy. In fact, many other metals are used in making alloys, which have different properties (and therefore uses) compared with the pure metals.

What is an alloy? An alloy is a homogeneous mixture composed of a metallic element mixed with one or more other elements (mostly metals). A few alloys contain small amounts of non-metals. An alloy is made by mixing a metal in molten state and one or more other elements together. The mixture is then allowed to solidify. For example, brass is an alloy of copper and zinc (Figure S10.1).

Although about 60 metals are commonly used, there are thousands of possible alloys. An alloy has properties different from its components. It is usually designed to have properties that are more desirable than those of its components. Alloys have suitable properties for making many many things, from a paper clip to a space shuttle.

Common alloys and their compositions The properties of some common alloys are shown in Table S10.1.
|Alloy |Approximate composition (by mass) |
|Mild steel |99.8% iron |
| |0.2% carbon |
|Stainless steel |73% iron |
| |18% chromium |
| |8% nickel |
| |1% carbon |
|Brass |70% copper |
| |30% zinc |
|Bronze |95% copper |
| |5% tin |
|Nickel-brass |70% copper |
|(a coinage metal) |24.5% zinc |
| |5.5% nickel |
|Cupro-nickel |75% copper |
|(a coinage metal) |25% nickel |
|Duralumin |95% aluminium |
| |3% copper |
| |1% magnesium |
| |1% manganese |
|Solder |67% lead |
| |33% tin |
|18-carat gold |75% gold |
| |25% silver and/or copper |

Table S10.1 Compositions of some common alloys.

We should note that only a few alloys are mentioned in the above table. In fact, a large variety of alloys are in use today. Besides, there are variations within the same type of alloy. For example, the brass (70% copper, 30% zinc) mentioned here is only the best known brass. There are many other different brasses, each with somewhat different compositions and properties.

Common properties of alloys and pure metals In a pure metal, all the atoms are of the same size. They are arranged regularly in layers. When an external force is applied, the layers slip over one another quite easily. Thus, pure metals have good malleability and ductility.

In an alloy, atoms of another element have been added to the pure metal. The addition of these different-sized atoms distorts the original regular crystal structure. As a result, slipping of layers now becomes difficult. This makes the alloy stronger, harder, less malleable and less ductile. See Figure S10.2. [pic] Figure S10.2 Layers of atoms cannot slip over one another easily in an alloy.

The melting point of a solid depends very much on the packing of atoms. A regularly packed solid has a higher melting point than an irregularly packed solid. An alloy, with an irregular structure, usually has a lower melting point than the metals from which it is made. Besides, alloying usually hinders the free movement of delocalized electrons. This lowers the electrical conductivity and thermal conductivity.

In general, compared with pure metal, an alloy ← is stronger and harder, ← is less malleable and ductile, ← has a lower melting point, ← has lower electrical and thermal conductivities.

Chapter 12 Reacting masses

■ Combustion analysis of organic compounds When we determine the empirical formula of an organic compound, we are usually provided with data like the masses of water and carbon dioxide produced during combustion of the organic compound. How do the data come from? Actually, the data are obtained from combustion analysis.

During combustion analysis, the sample is weighed and then burned in excess oxygen mixed with helium (Figure S12.1). After combustion, carbon dioxide, water vapour, nitrogen oxides and other compounds are produced. Compounds of sulphur, phosphorus and the halogens are absorbed by specific chemicals. The resultant mixture of gases is then allowed to pass through a hot mesh of copper. The hot copper mesh removes the excess oxygen and reduces the nitrogen oxides to nitrogen. The remaining gases are carbon dioxide, water vapour, nitrogen and helium.

[pic]Figure S12.1 A simplified diagram for combustion analysis.

These gases are then allowed to pass through a tube containing a mixture of sodium hydroxide and calcium hydroxide to remove the carbon dioxide. Then the remaining gases are allowed to pass through another tube filled with magnesium perchlorate (Mg(ClO4)2) to remove the water vapour. The tubes are weighed before and after the absorption process in order to find out the masses of carbon dioxide and water produced.
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[pic]Figure S1.3 We can ‘see’ the three states of matter at this beach.

[pic]
Figure S5.3 When the locations of the electron of a hydrogen atom at different instants are plotted, the above pattern is obtained. (The electron cloud model of a hydrogen atom.)

cathode ray

Supplement to Coursebook p.95

rotatable fluorescent screen

cathode (()

high voltage

thin gold foil

gas at very low pressure

shadow

6 V battery

light bulb

[pic]

syringe B

copper turnings turn black

air left

syringe A

syringe B

modified or new theory

Supplement to Coursebook p.284

[pic]
Figure S10.1 Brass is an alloy of copper and zinc.

zinc sulphide screen

metal cross

6 V battery

Supplement to Coursebook p.34

Supplement to Coursebook p.141

anode (+)

cathode (()

high voltage

Supplement to Coursebook p.96

lead shield

alpha particle source

hard-glass tube

reddish brown copper turnings

strong heat

air

cathode ray

y

x

z

y

x

plunger

syringe A

(a)

[pic]

beam of alpha particles

rotatable microscope

Supplement to Coursebook p.94

Supplement to Coursebook p.47

z

y

x

z

y

x

z

y

x

vacuum pump

evacuated glass vessel

electrons spread throughout the atom

sphere of positive charge

zinc sulphide screen

electric field

anode (+)

z

x

x

x

y

y

y

z

z

z

x

y

z

x

y

Supplement to Coursebook p.5

z

x

z

y

Schrödinger (1926)
(electron cloud model)

Niels Bohr (1913)
(energy levels)

Ernest Rutherford (1911)
(the nucleus)

John Dalton (1805)

J.J. Thomson (1904)
(positive and negative charges)

P

[pic]

(b)

nitrogen dioxide particles in random motion

air particles in random motion

remove glass plate and allow gas jars to stand

remove glass plate and allow gas jars to stand

nitrogen dioxide gas

air

gas jar

glass plate

predictions from theory

theory

P

atoms of other added elements

atoms of original metal

copper atoms

zinc atom

a brass saxophone

copper(II) chloride solution

copper

carbon cathode

chlorine gas bubbles

carbon anode

cathode

anode

electron flow

molten lead(II) bromide

negative electrode (cathode)

positive electrode (anode)

heat

[pic]

air

nitrogen dioxide gas

glass plate

hypothesis

law

further experiments

scientific facts from observation of nature or experiments

Learning tip
The electrons occupy different orbitals according to their energy status. Electrons with higher energy occupy orbitals that are further away from the nucleus.

Supplement to Coursebook p.223

Supplement to Coursebook p.198

Supplement to Coursebook p.197

Learning tip
Electrolytes are compounds which allow electricity to pass through them only when molten or in aqueous solution. There is chemical decomposition during the conduction.

6 V battery

HKDSE CHEMISTRY – A MODERN VIEW
COURSEBOOK 1
SUPPLEMENTARY INFORMATION

Supplement to Coursebook p.3

[pic]
Figure S1.6 Gas pressure (P) is caused by gas particles continually hitting the inner wall of the container. The gas pressure is the same on every part of the container.

deflected beams of alpha particles

electrons revolving around the nucleus

minute, positively charged nucleus

empty space

gold atoms

a stream of positively charged alpha particles enters the thin gold foil

a very small number of alpha particles approach a nucleus so closely that they are rebounded

most alpha particles pass through the thin gold foil undeflected

a few alpha particles come close enough to a nucleus to be deflected

polar molecule

hydrated chloride ion

hydrated sodium ion

chloride ion

sodium ion

=

dissolution

Zn

Zn

Zn

copper mesh to remove excess O2 and reduce nitrogen oxides

chemicals to absorb compounds of S, P and the halogens

heat

weighed sample of unknown compound

O2 + He

CO2 + H2O + N2 + He

Remove CO2

H2O + N2 + He

Remove H2O

N2 + He

electrodes

CHEMISTRY