Practise Ch2 Matter

8/3/2019 Practise Ch2 Matter

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Chapter 2 : The Structure of the Atom

A Matter

1. Matter is anything that occupies space and has mass. Matter exists in three states – solid, liquid

and gas.

2. Matter is made up of tiny and discrete particles.

3. An atom is the smallest particle of an element that can participate in a chemical reaction.

4. An ion is a positively-charged or negatively-charged particle.

5. Particles in matter are in motion.

6. Diffusion occurs when particles of a substance move in between the particles of another subtance.

7. Diffusion of matter occurs most rapidly in gases, slower in liquids and slowest in solids, due to thedifferent arrangement and movement of particles in the three states of matter.

The kinetic theory of matter.

(diagram)

i) The change in heat changes the state of matter.

ii) When a substance is heated, the particles gain kinetic energy and move faster.iii) When a substance is cooled, the particles loss their kinetic energy and move slower.

State of Matter

Characteristic

Solid liquid gas

Arrangement of particles are packed closelytogether in an orderly

manner

are packed closelytogether but not in

orderly manner

Very far apart and in arandom motion

Forces of attraction Strong forces Strong forces but

weaker than the forces

in a solid

Weak forces

Movement of particles Particles vibrate and

rotate about their

fixed positon

Particles vibrate,

rotate and move

throughout the liquid.

They collide against

each other

Particles vibrate,

rotate and move

freely. The rate of

collision is greater

than in liquid

Shape / volume - has a fixed volume

and shape

- has a fixed volume

and follows the shape

of the container

Does not have a fixed

shape of volume

compressibility Cannot be compressed Cannot be compressed

easily

Can be compressed

easily



Do it yourself 2.1

1.Figure 1 below shows the heating curve of a pure substance at room temperature and pressure.

Temperature/oC U

S T

119 Q R

P

Time / minute

Figure 1

(a)Describe the movement of the particles of the pure substance at stage PQ of the curve ?

(b)Draw a diagram to show the arrangement of particles of the substance at stage QR in the box below.

(c)Explain why the pure substance is not water ?

(d)Samples of the pure substance at stage RS and TU are taken. Compare the movement of the particles

of the substance at these two stages.

(e)After heating at 500oC, the substance is cooled. Draw and label the cooling curve.



2. P Q

U T S R

(a)Name the process in

P: Q :

R: S :

T: U :

(b)What will occur if matter undergoes a change of state ?.

(c)Compare the intermolecular distance and the packing of particles in the solid state and the liquid state.

Ice water Salt solution

water steam salt water

Applyheat Apply

heat

Saturate it thencool the solution

Boil it, then coolthe vapour



B The Atomic Structure

The historical development of atomic models.

Scientist Atomic Models

1. John Dalton

- imagined the atom as a small indivisible ball similar to a very tiny ball

2.J.J. Thomson

- described the atom as a sphere of positive charge which contains a few

negatively-charged particles called electrons.

3. Ernest Rutherford

discovered proton

the positive charge and most of the mass of the atom are concentrated in a

small, central region called the nuclues

electrons move in a space that is larger than the space occupied by the nucleus

4.Neils Bohr

proposed that the electrons in an atom move in shells around the nucleus

5.James Chadwick

proved the existence of neutrons, the neutral particles in the nucleus. Neutronscontribute approximately to half the mass of an atom.



Protons, neutrons and electrons are subatomic particles of an atom.

i) At

om

s

are

electrically neutral.

ii) The number of protons is equal to the number of electrons.

iii) The proton number of an element is the number of protons in its atom.

iv) The nucleon number of an element is the total number of protons and neutrons in its atom.

Therefore,

v) Each element has its own proton number.

vi) Each element is given a name and a symbol

Proton

number

Element symbol Proton

number

Element symbol

1 Hydrogen H 11 Sodium Na

2 Helium He 12 Magnesium Mg

3 Lithium Li 13 Aluminium Al

4 Beryllium Be 14 Silicon Si

5 Boron B 15 Phosphorus P

6 Carbon C 16 Sulphur S

7 Nitrogen N 17 Chlorine Cl

8 Oxygen O 18 Argon Ar

9 Flourine F 19 Potassium K

10 Neon Ne 20 Calcium Ca

An atom of an element can be written as A

X

Z

Where A is the nucleon number,

X is the symbol of an element,Z is the proton number.

Subatomic

particle

Symbol Relative

mass

Charge Location

Proton p 1 +1 In the nucleus

Electron e 1/1840 -1In orbits around

the nucleus

Neutron n 1 0 In the nucleus

Nucleon number = proton number + number of neutrons



Do it yourself 2.2

Complete the table below.

Complete the table below

Element

(symbol)

number of protons Number of neutrons Symbol of atoms

Lithium

(Li)

Neon

(Ne)

Zinc

(Zn)

Symbol of atom

27

Al

13

19

F

7

23

Na

11Proton number

Nucleon number

Number of protons

Number of electrons

Number of neutrons



2.3 Isotopes and Their Importance

1. The isotopes of an element are the atoms of that element which contain a same

number of protons, but a different number of neutrons.

2. Isotopes of some element

Element Isotopes

Hydrogen H1

1

1 proton0 neutron

H2

1

1 proton1 neutron

H3

1

1 proton2 neutrons

Carbon C12

6

6 protons6 neutrons

C13

6

6 protons7 neutrons

C14

6

6 protons8 neutrons

Oxygen O16

8

8 protons8 neutrons

O17

8

8 protons9 neutrons

O18

8

8 protons10 neutrons

Sulphur S32

16


S34

16


-

Bromine r B79

35

35 protons44neutrons

r B81

35


-

3. The uses of isotopes in daily life

Field Isotopes applications

Medical • Gamma rays from cobalt- 60 are used to killcancer cell without surgery in patient. Thistreatment is known as radiotherapy.

• Medical instrument are sterilized using gammarays.

• Radioactive materials such as iodide-131 areinjected into patients to detect malfunction of thyroid glands.

Archeology • Radioisotope carbon -14 is used to study theage of ancient artifacts.

Agricultural

• Carbon -14 is used to study the passage of

carbon in photosynthesis of green plants.

Industrial • Isotope sodium-24 is used to detect leakage of underground pipes.

SPM



4. The electron arrangement of elements with proton number 1 to 20.

( must know how to memorize)

2.4 Electron Arrangements / Electron Structures

Element Number of neutrons

Number of protons

Number of electrons

Number of nucleon

Electronarrangement

Number of valence

electrons

Hydrogen

Helium

Lithium

Beryllium

Boron

Carbon

NitrogenOxygen

Fluorine

Neon

Sodium

Magnesium

Aluminum

Silicon

Phosphorus

Sulphur

Chlorine

Argon

Potassium

Calcium

First shell: 2 electrons

Second shell: 8 electrons

Third shell: 8 electrons

Nucleus ( contains protons and nucleus)

Last electron/s in the last outermost shell, we

called as valence electron.

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Practise Ch2 Matter