STRUKTUR ATOM

THE STRUCTURE OF ATOMS

TOPIC 2: THE STRUCTURE OF ATOMS2.1: MATTER1. Particle Theory of Matter: Matter is made up of tiny and discrete particles

The tiny particles may be atoms, molecules or ions.

ACTIVITY 1: Determine the type of particles in the following substances:

SubstancesType of ParticleSubstancesType of ParticleSubstancesType of Particle

Hydrogen gas(H2)Sulphur dioxide(SO2) Tetrachloromethane(CCl4)

Copper(II) sulphate (CuSO4)Iron(Fe)Zink Chloride(ZnCl2)

Argon

(Ar)Carbon

(C)Hydrogen Peroxide(H2O2)

2. The Kinetic Theory of Matter Matter consists of small particles that always collide among each other. The particles move faster when energy is provided and slower when they are cooled.

3. The Evidences of Particles Theory of Matter and

Kinetic Theory of Matter

4. Change of states of matter based on the Kinetic Theory:

a) Comparison of characteristics of Solid, Liquid and gas:

State of matterSolidLiquidGas

Draw the particles arrangement

Particle arrangementThe particles are arrangedThe particles are ..The particles are arranged.

Particles movementParticles cannot move .. but can

at fixed positions Particles can move Particles move very ..

Attractive forces between the particlesVery..

.. (Particles are not tightly held)Very ..

Energy contentEnergy content

very ..Energy content Energy content

.. .high

b) When heat energy is supplied to matter, kinetic energy of the particles

in the matter increases and the particles in the matter vibrate faster.

When matter loses heat energy, the kinetic energy of the particles also

reduce and they vibrate less vigorously c)

The temperature at which a . completely changes to become a liquid is called its

..

Activity 2.4 page 9 [practical book] Description of Experiment

- Apparatus set-up - Precautions taken

The Explanation of the Heating Process

A

Time/s

When the solid is heated, the particles move faster and its energy content increases. This is because it absorbed heat. Therefore, the state of matter is changed.

PointState of matterExplanation

A to B

B to C

C to D

D to E

E to F

Freezing point: Refer to the temperature when a .. changes to .

During the freezing process, the temperature remains unchanged because the heat lost to the environment is .. by the heat released when the liquid particles rearranged themselves to become solid.THE EXPLANATION FOR THE COOLING PROCESS OF MATTER

PointState of MatterExplanation

P to Q

Q to R

R to S

2.2: THE ATOMIC STRUCTURE

1. History of the development of atomic models NumberAtomic model [draw]Discovery

1Dalton

i. Matter is made up of particles called atom

ii. Atom cannot be created, destroyed or divided into smaller particles.

iii. Atoms from the same element are the same.

iv. Atoms are hard physical body that cannot be penetrated.

2Thomson

3Rutherford

4Neils Bohr

5James Chadwick

2. Subatomic particlesSubatomic particles SymbolChargeRelative atomic massPosition

Electron

Proton

Neutron

a. Proton Number =number of protons in the nucleus of an atom in an element.

Number of protons = number of electrons in a neutral atom.

b. Nucleon Number=The total number of protons and neutrons in an atom

=proton number + number of neutronc. Symbol of element

A

X

Z X - Symbol of Element

A - Nucleon number of atom X

Z - Proton number of atom X

d. Example :

i. 39

K The element: . has a nucleon number of , proton number of ,

19 So, the number of neutrons equals the number of protons equal ,

and the number of electrons equals.

3 Isotope:

Example: 1 Nucleon number = 2 Nucleon number =

H Proton number = number of proton= H Proton number = number of proton =

1 number of neutron = 1 number of neutron =

Atoms from the same elements with the .. proton number or the same number of protons but ____________ in nucleon number because of the difference in the number of neutrons. Isotopes have the same . properties but different properties because they have the same electron arrangement.Usage of isotopes:

1.In the medical field To detect brain cancer.To detect thrombosis (blockage in blood vessel).Sodium-24 is used to measure the rate of iodine absorption by thyroid gland.Cobalt-60 is used to destroy cancer cells.To kill bacteria in the sterilizing process.2. In the industrial field To detect wearing out in machines.To detect any blockage in water, gas or oil pipes.To detect leakage of pipes underground.To detect defects/cracks in the body of an aeroplane.

3. In the agriculture field To detect the rate of absorption of phosphate fertilizer in plants.To sterile insect pests for plants. 4.In the archeology field Carbon-14 can be used to date objects.5. Electron Arrangementa) The electrons are filled in specific shells. Every shell can be filled only with a certain number of electrons. For the elements with atomic number 1-20:- First shell can be filled with a maximum of ___ electrons.

Second shell can be filled with a maximum of ______ electrons.

Third shell can be filled with a maximum of _______ electrons.

b) Symbol of Element

Hydrogen Atom

Helium Atom

Lithium Atom

Beryllium Atom

Sodium Atom

c) Valence electron: Electron in the outermost shell of a neutral atom.Activity 2: Complete the following:

AtomNumber of protonsNumber of electronsNumber of neutronsNucleon NumberElectron arrangementValence electron

P66

Q68

R1112

S1515

T1631

U1920

V1224

W272.8.3

.atom and atom are isotopes because they contain the same number of . but different number of ...

Exercise

1.An experiment is conducted to study the changes in the state of matter. A black solid is heated from room temperature until 200 o C as shown in the diagram below. At 180o C the solid T changed directly into a purple gas.

a.Name the process that solid T undergoes.

b.Draw the particle arrangement in solid T and gas T.

Solid T

Gas T

c. Sketch the graph of temperature against time for the heating of solid T.

d.What can be observed at position R of the round bottom flask?

.

e.Why cant the coconut oil in the experiment be replaced with water?

.

.

2. The melting point of acetamide can be determined by heating solid acetamide until it melts as shown in the diagram below. Then the temperature of acetamide is recorded every three minutes when it is left to cool at room temperature.

a. What is the purpose of using water bath in the experiment?

b. Name another substance that its melting point can also be determined by using water bath as shown in the above diagram.c. Sodium nitrate has a melting point of 310oC. Can the melting point of sodium nitrate be determined by using the water bath as shown in the diagram? Give an explanation.

.

.

..

d. Why do we need to stir the acetamide in the boiling tube in the experiment above?

e. The graph of temperature against time for the cooling of liquid acetamide is shown below.

temperature/oC

P

100

90

Q

R

80

70

60 S

time/minutes

i. What is the melting point of acetamide?

.

ii. The temperature between Q and R is constant Explain.

f. Acetamide exists as molecules. Name another compound that is made up of molecules.

.

3. a.Explain the following terminologies, giving a suitable example for each item.

i. atom

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ii. molecule

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iii. element

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iv. compound

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4) Complete the following table:

ElementsIsotopesNumber of protonsNumber of electronsNumber of neutrons

Hydrogen

Oxygen

5. Table 1 shows the proton number and the nucleon number of four atoms.

AtomProton numberNucleon number

P511

Q1735

R1737

S2040

a) What is meant by the proton number and the nucleon number of an atom?

..

b) State the number of protons, neutrons and electrons that are present in atom P.

..

c) Represent atom Q in the form of

..

d) (i)Write down the electron arrangement of atom R?

(ii)What is the number of valence electrons in atom R?

..

e) Which of the atoms are isotopes? State a reason for your answer.

..

f) Draw a diagram to show the arrangement of electrons around the nucleus of atom S.6. (a) Table 2 shows the results of two experiments to study diffusion of particles in solid and liquid.

ExperimentObservation

Experiment I : Diffusion of potassium manganate(VII) in waterThe purple colour of potassium manganate(VII) slowly spreaded throughout the water in a few hours.

Experiment II : Diffusion of potassium manganate(VII) in gelThe purple colour of potassium manganate(VII) slowly spreaded into the gel. After a few days, the gel turned entirely purple.

(i) What is the meaning of diffusion?

(ii) Explain why there is a difference in the observation...(b) Solid X has a melting point of 700C. A boiling tube containing solid X is heated at room temperature using a water bath until its temperature is above its melting point.

(i) What is the meaning of melting point?

..

(ii) Sketch the arrangement of particles of X at 800C and 400C respectively.

(iii) Sketch a graph of temperature against time during the heating.

(iv) Explain the shape of the graph.

..(c) (i) What is meant by a valence electron?

(ii) Element Y has proton number 13. State the number of valence electrons in atom Y.

.

6. An experiment was conducted to find out the freezing point of liquid X. A boiling tube containing molten X at 950C was allowed to cool in a conical flask to room temperature. The temperature of X recorded at half-minute intervals. Figure 1 shows the reading of the thermometer for this experiment.

Figure 1.

(a) Record the temperature at each time interval in the spaces provided in figure 1.(b) Construct a table to record the data shown in figure 1.(c) (i)Draw a graph of temperature against time.(ii)On your graph, mark the freezing point of X.(d) What happened to the temperature when X was freezing?

(e) Why was the boiling tube placed in the conical flask during the cooling?

........................................................................................................................................

THE STRUCTURE OF ATOM

1. Which of the following substances will become gas when heated without becoming a liquid?

AIce

BIron

CIodine

DSodium chloride

2. The diagram shows a model of an atom.

Who introduced this model?

ANeils Bohr

BJohn Dalton

CJames Chadwick

DErnest Rutherford

3. Table 1 shows the melting point of substances P,Q,R and S.

Substances Melting point/oCBoiling point/oC

P-187-126

Q-7870

R75130

S114444

TABLE 1

AP

BQ

CR

DS

4. Which of the following processes is not true?

ProcessChange of stateChange of energy content

ABoilingLiquid to gasEnergy is absorbed

BFreezing Liquid to solidEnergy is produced

CCondensation Gas to liquidEnergy is produced

DEvaporation Solid to gasEnergy is produced

5. Which of the following scientist has given the latest accepted structure of an atom?

ScientistStructure of the atom

ANeils BohrElectrons move in a circular orbit around the nucleus along a fixed shell

BJohn DaltonThe atom is spherical in shape and is made up positive charges with negative charged electrons moving around them

CErnest RutherfordEvery matter consists of small particles known as atoms

DJ.J.Thomson The alpha particle is the positively charged particle

6. Figure 1 shows graphically the heating effect of substance S?

Temperature/oC

80(

0 t1 t2 time/minute

What are the conclusions that can be made from the graph?

I.The melting point of substances S is 80oC.

II.At the time t1 substance S begins to melt.

III.After the time t2, all the mass of substance S has changed to the liquid state.

IV.Substance S is in both the liquid and solid states from the time t1 to t2.

A.I and III only

C.I,II and IV only

B.I and IV only

D.I ,II,III and IV

7. Table 2 shows the proton number for the elements I,J,K,and L.

ElementProton number

I3

J8

K10

L19

Table 2

Which of the elements has 4 electrons shells?

A.I

B.J

C.K

D.L

8. What is the maximum number of electrons that can fill the first shell of an atom?

A2

C8

B4

D18

9. Table 3 shows the number of protons for elements P,Q,R,S, and T.ElementsPQRST

Proton numbers38101120

Table 3

Which of the following has the same electron valence?

AElement P and element S

CElement R and element S

BElement Q and element S

DElement S and element T

10. Which of the following shows that the sodium atom and the potassium have the same similar feature(s)?

IThe electron number

IIThe number of electron shells

IIIThe number of electrons

IVThe number of neutrons

AI and II only

C.I,II and III onlyB.II and IV only

D.I ,II,III and IVTHE ATOMIC STRUCTURE

HISTORY OF ATOMIC MODELS DEVELOPMENT

To state the contribution of scientists in the atomic structure model such as the scientists who discovered electron, proton, nucleus, neutron and shell.

SUBATOMIC PARTICLES

To compare and differentiate subatomic particles i.e. proton, neutron and electron from the aspect of charge, relative mass and location.

To state the meaning of Proton Number and Nucleon Number based on the subatomic particle

To write the symbol of elements with proton number and nucleon number

ISOTOPE

To state the meaning, examples and the use of isotopes

ELECTRON ARRANGEMENT

To know the number of electron shells and electrons in the 1st, 2nd and 3rd shell

To write the electron arrangement of atoms based on proton number or number of electrons and state the number of valence electron

MATTER

PARTICLE THEORY OF MATTER

To state the particle theory of matter

To differentiate and draw the THREE TYPES OF PARTICLE i.e.

atom, ion and molecule

KINETIC THEORY OF MATTER

To state the kinetic theory of matter

To relate the change of physical states of matters with energy change

To relate the change of energy in the particle with kinetic particle theory of matter

MATTER

Ion

COMPOUND:

ELEMENT:

Types of particles

Types of particles

A neutral particle consists of similar non-metallic atoms which are covalently-bonded.

Examples:

Figure:

The smallest neutral particle of an element [Normally pure metals , Noble gases and a few non-metal elements such as carbon and silicon.

Examples:

Figure:

Molecule

Atom

Molecule

Positively or negatively charged particles, which are formed from metallic atom and non-metallic atom respectively. The force of attraction between the two oppositely charged ions is an ionic bond.

Examples:

Figure:

A neutral particle consists of different non-metallic atoms which are covalently-bonded.

Examples:

Figure:

B

C

D

E

Temperature/(C

F

CONDENSATION

Gas

Liquid

Solid

MELTING

BOILING

FREEZING

Matter experiences change of state when heat energy is absorbed or released

Matter is made up of tiny and discrete particles

-Estimation of the size of oil molecule

Matter consists of mobile particles.

Act 2.1 page 6 [practical book]

-diffusion

Act 2.3 page 9 [practical book]

-melting and freezing points of napthelene

Particles in matter are constantly colliding

- Brownian Movement

First shell-filled with 2 electrons (duplet)

Time/s

S

Q

R

P

Temperature/(C

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

(

Heat

Coconut oil

Solid T

Ice

Heat

acetamide

water bath

test tube

thermometer

Examples:

Oxygen: O, Aluminum: Al

Magnesium: Mg, Calcium: Ca

Nitrogen: N, Chlorine: Cl

Sodium: Na, Hydrogen: H

Second shell filled with 8 electrons (octet)

x

Third shell filled with 8 electrons (octet)

Number of protonsNumber of electronsNumber of neutronsProton numberNucleon numberElectron Arrangement

1

1

H

(

4

2

He

(

(

Number of protonsNumber of electronsNumber of neutronsProton numberNucleon numberElectron Arrangement

Li

7

3

(

(

Number of protonsNumber of electronsNumber of neutronsProton numberNucleon numberElectron Arrangement

Be

9

4

(

(

(

(

Number of protonsNumber of electronsNumber of neutronsProton numberNucleon numberElectron Arrangement

Na

23

11

(

(

(

(

(

(

(

(

(

(

(

Number of protonsNumber of electronsNumber of neutronsProton numberNucleon numberElectron Arrangement

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