2 the structure of the atomic structure

WAJA F4 Chemistry 2010 Chapter 2: The Structure of Atom

CHAPTER 2: THE STRUCTURE OF ATOM

A MATTER

Activity 1

Fill in the blanks with suitable word(s) in the box given

1. Matter is made up of ………………………. and …………………… particles.

2. The tiny particles may be atoms ……………….. and ……………………….

3. An atom is the ………………… particle of an element that can …………………….. in a chemical

reaction.

4. A molecule is a group of two or more …………………… which are …………………… bonded

together.

5. An ion is a …………………………………. or negatively – charged particle

6. Diffusion occurs when particles of a substance move ……………… between the particles of

another substance.

7. Diffusion of matter occurs most rapidly in ………………… state, slower in ………………….. state

and slowest in …………………….. state. This is due to the different ……………………… and

………………………. of particles in the three states of matter.

8. Matter consists of small particles that always collide among each other. The particles move faster

when energy is …………………… and the particles move slower when the energy is ….

………………..….

Activity 2

1. Complete the table below.

State of matter Solid Liquid Gas

Draw the

arrangement of

particles

Arrangement of The particles are The particles are The particles are

Learning OutcomesYou should be able to:

describe the particulate nature of matter, state the kinetic theory of matter, define atoms, molecules and ions, relate the change in the state of matter to the change in heat, relate the change in heat to the change in kinetic energy of particles, explain the inter-conversion of the states of matter in terms of kinetic theory of matter.

Ions tiny molecules discrete smallest take part positively-charged in released atoms gas chemically solid absorbed different arrangement movement liquid

1


particles

packed ……………..

together in an

…………………………

manner

packed ……………….

together but not in ….

……..……………….

………………………….

…………….. apart from

each other and in

……………………………

motion.

Movement of

particles

Particles can only

…………………… and

………………….. about

their fixed positions

Particles can

………………………...,

….……… and…………

throughout the liquid.

Particles can

………………………….,

……………………… and

……………. freely

Attractive forces

between the

particles

Particles are attracted

by very ……………..

…………….. between

the partcles

Particles are held

together by strong

forces but ……………..

than the forces in solid

(moderately)

The attraction forces

between particles are

……………….… forces

Energy content of

particles …………………….. ………………………. ……………………………

2. Underline the correct word in the passage below.

When heat energy is supplied to particles in matter, its kinetic energy (increases /decreases) and

the particles in matter vibrate ( faster/ slower). When matter loses heat energy, the kinetic energy

of the particles (increases/decreases) and they vibrate ( faster/ slower).

3. State the change of matter for each conversion in the spaces provided.

A …………………………… B …………….……………….. C……………..……………..

D……………………………. E …………………………….. F ……………………………

4. Complete the passage below by using the words given below.

2

Temperature/ OC

A

B

C

D

Time/s


(solid, gas, boiling point, melting point, solid, gas, liquid, intermolecular, released, absorbed, overcome )

The temperature at which a ………………………………… completely changes to a liquid is called

……………………………… Boiling point is the temperature at which a …………………… changes

into …………….. . During the boiling process, the temperature remains constant because the

heat

energy is …………………… by the particles and is used to …………………...………………… the

…………………………… forces between particles.

5. The graph below shows the change in temperature with time when a matter in solid state was heated.

Based on the graph above, complete the table below.

Point States of matter Explanation in terms of energy change and movement of particles

A to B

Heating causes the particles to ……………………….. more

energy and vibrate ……………………….. The temperature of

the substance and the kinetic energy

…………………………………

B to C

Continuous heating does not cause the temperature of the

substance to increase. The energy absorbed is used to

…………………………… the forces of attraction between the

………………………. The constant temperature is called the

…………………..…………………………………………..

C to DContinuous heating causes the temperature of the liquid to

…………………………… The particles move……………………

because their kinetic energy ………………………………………..

3


6. (a) The graph below shows the change in temperature with time when a matter in liquid state is left to cool.

Based on the graph above, complete the table below.

Point State of matter Explanation

P to QAs cooling continues, particles lose their…………………………

and move ………………………. . The temperature……………...

Q to RThe stronger bonds ……………………. during freezing release

energy. This energy released is the same as the energy

………………. to the surroundings during cooling. Thus the

temperature remains unchanged. This constant temperature is

called …………………………..

R to SThe ………………is cooled. The particles vibrate……………….

as the temperature ……………………….

(b) Complete the passage below by using the words given below. (solid, gas, liquid, exactly balanced, decreased, increased)

Freezing point is the temperature at which a …………………… changes into ………………………

During the freezing process, the temperature remains unchanged because the heat lost to the

environment is …………………….….. by the heat released when the liquid particles rearrange

themselves to become solid.

B THE ATOMIC STRUCTURE

Temperature / OC

Time/s

PQ R

S

Learning OutcomesYou should be able to: describe the development of atomic model, state the main subatomic particles of an atom, compare and contrast the relative mass and the relative charge of the protons, electrons and neutrons, define proton number, define nucleon number, determine the proton number, determine the nucleon number, relate the proton number to the nucleon number, relate the proton number to the type of element, write the symbol of elements, determine the number of neutrons, protons and electrons from the proton number and the nucleon

number and vice versa, construct the atomic structure.

B

A

A

A

4


Activity 3

1. Complete the table and draw the structure of each atomic model.

Model Structure Characteristic

Dalton’s atomic model proposed by

…………………… in 1805

The atom was imagined as a small indivisible ball similar to a very tiny ball.

Thomson’s atomic model proposed by

……………………..in 1897

J.J Thomson discovered ……………….., a negatively-charged particle.The atom was described as a sphere of positive charge embedded with electrons.

Rutherford’s atomic model proposed by

…………………… in 1911

Ernest Rutherford discovered ……………., a positively-charged particle in an atom.The central region of atom has a very small positively-charged …………………..…, which contains almost all the mass of the atom.

Bohr’s atomic modelproposed by

……………………in 1913

The electrons in an atom move in ………..……… around the nucleus which contains protons.

Chadwick’s atomic modelproposed by …………..…………. in 1932

Chadwick proved the existence of ……………….., the neutral particle in the nucleus.The nucleus of the atom contains protons & neutrons, and the nucleus is surrounded by electrons.

Activity 4

Fill in the blanks and complete the table.

1. Atoms are made up of subatomic particles namely protons, …………… and ………….. 2. ………………………and …………….. are found in the nucleus of an atom while electrons

surround

the nucleus.

3.Subatomic particle Symbol Relative mass Relative electric charge

Proton

Neutron

5


Electron

4. The proton number of an element is the number of ………………… in its atom.

Proton Number, Z = Number Of Proton

5. Protons and neutrons are collectively called nucleons.

The nucleon number of an element is the total number of ………………….. and

……………….. in its atom.

Nucleon Number, A = Number Of Proton + Number Of Neutron

6. The nucleon number is also known as the ……………………………..

……………………… = Nucleon Number -- Proton Number = A -- Z

7. The standard representation for an atom of any element shows the proton number and the nucleon number of the element. It can be written as follows:

A XZ # A – Nucleon number Z – proton number X – symbol of element

1H1

21Sc45

Proton number Nucleon number

2He4

3Li7

4Be9

5B11

6C12

7N14

8O16

9F19

10Ne20

11Na23

12Mg24

13Al27

14Si28

15P31

16S32

17Cl35

18Ar40

19K39

20Ca40

21Sc45

By referring to part of the Periodic Table of Element above, complete the table below.

Element SymbolProton number

No. of neutrons

Nucleon number

No. of electrons

Standard representation

Scandium

Aluminium

Argon

Beryllium

6


Boron

Calcium

Carbon

Chlorine

Fluorine

Helium

Hydrogen

Lithium

Magnesium

Neon

Nitrogen

Oxygen

Phosphorus

Potassium

C ISOTOPES AND THEIR IMPORTANCE

Activity 5 Fill in the blanks.

1. Isotopes are atoms of the same element with the ………………………. of proton but

……………………………….. of neutron.

2. Complete the table below:

ElementNumber of isotopes

Symbol of isotopes

Number of protons

Number of electrons

Number of neutrons

Name of isotope

Hydrogen 3

11 H 1

1 Hydrogen-2

1 2

Oxygen 38

16 O 8 8 Oxygen-16

8 9

Learning OutcomesYou should be able to: state the meaning of isotope, list examples of elements with isotopes, determine the number of subatomic particles of isotopes, justify the uses of isotope in daily life.

7

Use ‘x’ as symbol for electrons. Draw the maximum number of electrons in each shell.


818 O

Carbon 3

6 Carbon-12

6 7

614 C 6 8

Chlorine 2 1735 Cl 17

17 20

Bromine 235 Bromine-80

35 35 Bromine-81

3. For each of the isotope list below, state one of its uses. a) Gamma rays of Cobalt-60: ………………………………………………………………….

b). Carbon-14: ………………………………………………………………………………….. c). Phosphorus-32: ……………………………………………………………………………..

d). Sodium- 24: …………………………………………………………………………………

e). Iodine -131: ……………………………………………………………………………………

D THE ELECTRONIC STRUCTURE OF AN ATOM

Activity 6

1. Electrons are filled in specific shells, starting with the shell nearest to the nucleus of the atom.

Every shell can be filled only with a certain number of electrons.

The first shell can be filled with a maximum of ……………. electrons

The second shell can be filled with a maximum of ……………. electrons

The third shell can be filled with a maximum of …………….electrons

Learning OutcomesYou should be able to: describe electron arrangements of elements with proton numbers 1 to 20, draw electron arrangement of an atom in an element, state the meaning of valence electrons, determine the number of valence electrons from the electron arrangement of an atom.

8


2(a) Draw the electron arrangement of a sodium atom, in the box and complete the table given.

(b) Draw the electron arrangement of a chlorine atom, Cl in the box and complete the table given.

3 Valence electrons are electrons in the ………………..………… shell of a neutral atom.

4 Identify the number of valence electrons in these atoms according to its electron arrangement.

Atom of Element Electron Arrangement Number of valence electrons

Oxygen 2.6

Aluminium 2.8.3

Chlorine 2.8.7

Neon 2.8

Potassium 2.8.8.1

Magnesium 2.8.2

Carbon 2.4

Phosphorus 2.8.5

x

x

9

Number of protons

Number of electrons

Number of neutrons

Proton number

Nucleon number

Electron arrangement

Number of protons

Number of electrons

Number of neutrons

Proton number

Nucleon number

Electron arrangement


Helium 2

10

2 the structure of the atomic structure

Technology