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 particles / The particles are packed …………….. together in an ………………………… manner / The particles are packed ………………. together but not in ….……..……………….
…………………………. / The particles are …………….. 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.

(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 D / Continuous heating causes the temperature of the liquid to …………………………… The particles move…………………… because their kinetic energy ………………………………………..

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 Q / As cooling continues, particles lose their…………………………
and move ………………………. . The temperature……………...
Q to R / The 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 S / The ………………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

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 model
proposed by
……………………in 1913 / The electrons in an atom move in ………..……… around the nucleus which contains protons.
Chadwick’s atomic model
proposed 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
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 / X
Z

# A – Nucleon number

Z – proton number

X – symbol of element

1
H
1 / 21
Sc
45 / Proton number
Nucleon number / 2
He
4
3
Li
7 / 4
Be
9 / 5
B
11 / 6
C
12 / 7
N
14 / 8
O
16 / 9
F
19 / 10
Ne
20
11
Na
23 / 12
Mg
24 / 13
Al
27 / 14
Si
28 / 15
P
31 / 16
S
32 / 17
Cl
35 / 18
Ar
40
19
K
39 / 20
Ca
40 / 21
Sc
45

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

Element / Symbol / Proton number / No. of neutrons / Nucleon number / No. of electrons / Standard representation
Scandium
Aluminium
Argon
Beryllium
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:

Element / Number of isotopes / Symbol of isotopes / Number of protons / Number of electrons / Number of neutrons / Name of isotope
Hydrogen / 3 / / 1
1 / Hydrogen-2
1 / 2
Oxygen / 3 / / 8 / 8 / Oxygen-16
8 / 9
Carbon / 3 / 6 / Carbon-12
6 / 7
/ 6 / 8
Chlorine / 2 / / 17
17 / 20
Bromine / 2 / 35 / 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

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

Number of protons
Number of electrons
Number of neutrons
Proton number
Nucleon number
Electron arrangement

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

Number of protons
Number of electrons
Number of neutrons
Proton number
Nucleon number
Electron arrangement

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
Helium / 2

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