153876503 Chemistry Form 4 Chapter 2 1

8/13/2019 153876503 Chemistry Form 4 Chapter 2 1

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ParticulateTheory Of Matter

Matter

-occupies space, has mass &volume

-Made up of tiny discrete particles

-Either elements/ compounds

-Either atoms, molecules/ ions

Element

-Made up of single type of

atoms

-Chemical reaction cant

break downa substance of

an element

Compound

-Made up of 2/more

elementswhich are held

together by chemical bonds.

-Made up of molecules /ions

Atoms

-Smallest neutral particles in an

element &take part in chemical

reaction

Ions

Metals=positive+ (Cation)

Non-metals =negative(anion)

Molecules

-Neutral particles

-Is a group of 2/more atoms that

chemically bonded together.

-Made up of atoms of the same

&different element

Molecules

-Neutral particles

-Is a group of2/more atoms that

chemically bonded together.

-Made up of atoms of the same&different element

Exp of Atoms:

Na=sodiumC=carbon,

He=Helium, Ne=Neon,

Al=Aluminum

Exp of Molecules:

Nitrogen=N2Oxygen=O2

Fluorine=F2

Chlorine=Cl2

Bromine=Br2Iodine=I2Pho

sphorus=P4Sulphur=S8

Exp of Molecules:

Water=H2O

Ammonia=NH3Methane

=CH4Carbon

dioxide=CO2

Cation:Mg2+

Cu2+

H+Al

3+

Anion: Cl-,I

-,OH

-,O

2-


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Diffusion

Always collide among each

other & affected when heat is

provided.

Move from high

concentration

lowerconcentration

Move rapidly in gases, slower in

liquid & slowest in solid.Diffusion in gas

Diffusion in liquid

Bromine gas is made up of tiny &

discrete particles. These particles

move randomly into the spaces in

between the air particles.

Diffusion in solid

Potassium

manganate(Vll) is made

up of tiny & discrete

particles. These particles

move slowly into the

spaces in between the

water molecules.

Potassium manganate(Vll) crystal dissolves &

the particles move very slowly into the

spaces in between the gel particles.

Notes: Speed of diffusion depends:

The higher the temperature, the faster the

particles move & hence the faster the diffusion.

The smaller the mass, the faster the particles

move & the faster the speed of diffusion


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Kinetic Theory of Matter

State Solid Liquid Gas

Particles arrangement

Packed closely together orderly

manner

Packed closely but not in orderly

arrangement

Very far apart from each

other&in a random arrangement

Particles movement The particles can only vibrate &rotate about their fixed positions

-Rotate,vibrate&move

throughout the liquid.

-They collide against each other.

-Particles can move freely

-Rate of collision is greater than

the rate of collision in a liquid

Attractive forces Strong forces between theparticles

The particles r held together by

strong forces but weaker than

the forces in a solid.

Weak forces between the

particles

Kinetic energy of particles Low energy content asmovement is restricted

Higher energy content as

particles can move easily

High energy(particles move at

random)

Properties Solid Liquid GasShape Definite shapes Takes the shape of the container Takes the shape of the container

Volume Fixed volume Fixed volume Takes on the volume of thecontainer

Density High Medium Low


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Compressibility Not compressible bcoz theparticles r very closely packed

Difficult to compress bcoz the

particles r closely packed

Easily compressed bcoz the

particles r far apart

a) Solid, liquid&gashas kinetic energybcoz the particles r in constant motion&collide with each other.b) The higherthe temperature, the higherthe kinetic energyof the particles which movewith higher speeds.c) The pressureof agasis due to the collisionsof the gas on the wall of the containerand the collisions are elastic(with no

energy lost in collisions)

Solid Liquid Gas

a) A matter changesits state form at a particular temperature&pressure.b) To change solid to liquid,liquid to gas &solid to gas, we have to overcome the forces of attraction between the particles in its originalstate.Thereforeheat energy must be absorbedto effect this change.c) For the changes of gas to liquid, liquid to solid, &gas to solid to take effect, heat energy must be released. As the particles lose heat energy, their

kinetic energy decreases. They move slower & the forces of attraction between them become stronger.

d) SolidGas

Melting

Freezing

Boiling/Evaporation

Condensation

Sublimation

Sublimation

Heating process

Cooling process

Heat energy absorbed,

Temperature rises

Heat energy released,

Temperature drops

Heat is absorbed by the substance until the solid completely changed into a liquid without a change in temperature =

Latent heat of fusion


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e) GasSolid

Heating curve

Heat energy that is provided to the substance to convert liquid to gas =

Latent heat of vaporisation

Temperature (OC)

Time (minute)

F

ED

CB

A

Begins to boil

Begins to melt

Begins to melted

Completely

vapourised

Boiling point

Melting point

Room

temperature

Boiling pointis the temperature at which a liquid changes

into a gas at a particular pressure.

Melting point is the temperature at which a solid changes

into a liquid at a particular pressure.

A to B: Solid

When the solid is heated, heat energy is absorbed to

gain kinetic energy&vibrate faster. The temperature

increasesas the particles received more heat energy.

B to C: Mixture of solid & liquid

The temperature does not rise, even though heating continues. The temperature

remains constantbcoz the heat energy absorbedby the particles is used to overcome the

forces between particlesso that the solid can turn into liquid.


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Cooling curve

C to D: Liquid

Theparticles in liquid absorb heat

energy&move faster. The temperature

continues to increase.

D to E: Mixture of liquid & gas

The temperature remains constantbcoz the heat

energy absorbed by the particles is used to overcome

the forces between particlesso that the liquid can

turn into gas.

E to F: Gas

Theparticles in liquid absorb heat

energy&move faster. The temperature

continues to increase.

B C

DE

F

A

Temperature (OC)

Time (minute)

Boiling point

Room

temperature

Freezing point

Begins to condense

Begins to freeze

Completely frozen

Completely condensed

A to B: Gas

When the gas is cooled, the

particles in the gas lose their

kinetic energy. They move sloweras the temperature decreases

B to C: Mixture of gas & liquid

The temperature remains

constantbcoz the heat surrounding

is exactly balanced by the heat

energy liberatedas theparticles

attract one another to form a liquid.

C to D: Liquid

The particles in liquid lose

heatenergyto theenvironment&move slower.

Hence, the temperature

decreases.

D to E: Mixture of liquid & solid

The temperature remains constantbcoz the

heat loss to the surroundings is exactly

balanced by the heat energy liberated as the

particles attracted one another to form a solid.

E to F: Solid

The particles in solidcontinue to

lose heat energy to the

environment&vibrate slower.

Hence, the temperature

decreases to room temperature.

James Chadwick (1922)

- Discovered neutrons, the neutral particles in the cell- Nucleus contains protons & neutrons with electrons

surrounding the nucleus in permitted cells.Electron

Positively charged

sphere


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The Atomic Model

John Dalton (1803)

-All elements made up small invisible particles =

atoms

-Atoms cant be created / destroyed

-Atoms look like spheres

J.J Thomson (1897)

-Atom made up of positively-charged sphere

with negatively charged atom

- Electron is about 2000 times lighter than

hydrogen atom.Neils Bohr (1913)

-Electrons moved around the nucleus in fixed

shells which contain protons.

Ernest Rutherford (1911)

-Some alpha particles penetrated the gold plate & went

through deflection, some were deflected, while some

rebounded.

-positively charged particles = protons

-Mass of an atom was concentrated in a small positively

charged area = nucleus

Tiny invisible

particle

Electron

Electron

Nucleus

Nucleus


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Atomic Structure

Isotopes and Their Importance

Particle Symbol Relative

Charge

Relative

Masses

Proton p +1 2

Neutron n 0 1

Electron e -1 1/1840

Electron (move around the nucleus)

Nucleus:

Proton & Neutron

Nucleus is positively charged

bcoz presence of protons.

A neutral atom contains the same number of electron

as the protons.

Symbol of element

Nucleon number (mass number)

Proton number (atomic number)

Proton number = number of proton

Nucleon number of an element is the total number of

protons & neutrons in its atom.

The relative mass of an atom is almost the same as its

nucleon number

Nucleon number = number of protons +

number of neutrons


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Element Name of isotopes Protons Neutrons Proton

number

Nucleon number

Hydrogen Hydrogen1

Hydrogen2Hydrogen3

1

11

0

12

1

11

1

23

Carbon (3

isotopes)

Carbon12

Carbon13

Carbon14

6

6

6

6

7

8

6

6

8

12

13

14

Oxygen (3

isotopes)

Oxygen16

Oxygen17

Oxygen - 18

8

8

8

8

9

10

8

8

8

16

17

18

Chlorine (2

isotopes)

Chlorine35

Chlorine37

17

17

18

20

17

17

35

37

Bromine (2isotopes )

Bromine79Bromine81

3535

4446

3535

7981

Isotopes

Isotopes are atoms of the same element with

the same number of protons (proton number)

but different numbers of neutrons (nucleon

numbers)Isotopes of an element have the same

chemical properties bcoz they have the

same electron arrangement.

Isotopes of an element have different

physical properties bcoz they have

different relative isotopes masses

Gamma radiation from the

decay of cobalt-60 is used to

destroy cancer cells

Gamma radiation is also used

to sterilize surgical rubber

gloves, medicines & plastic

hypodermic syringes


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Electronic Structure of An Atom

Electrons in the outermost shell are

called the valence electrons. This atom

has 1 valence electron.

The third shell can take a maximum of

18 electrons. However the atom attains

stability if the third shell is filled with 8

electrons.

Nucleus of the atom containing protons

& neutrons

First shell can take a maximum of 2

electrons.

Second shell can take a maximum

of 8 electrons.

Valence shell

1) The electrons are arranged in shells surrounding the nucleus.2) The electrons are filled starting from the first shell, the one closest to the nucleus.3) The occupied shell which furthest from the nucleus is called the valence shell / outermost shell. The electrons in the


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Electron Arrangement of Elements with Proton Numbers 1 to 20

Element Electron

arrangement

Element Electron

arrangement

Hydrogen 1 Sodium 2.8.1

Helium 2 Magnesium 2.8.2

Lithium 2.1 Aluminium 2.8.3

H1

1

He

Li

Na

Mg

Al

4

27

24

23

7

212

11

133


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Beryllium 2.2 Silicon 2.8.4

Boron 2.3 Phosphorus 2.8.5

Carbon 2.4 Sulphur 2.8.6

Nitrogen 2.5 Chlorine 2.8.7

Oxygen 2.6 Argon 2.8.8

Fluorine 2.7 Potassium 2.8.8.1

Be

B

Si

O

K

Ar

Cl

S

N

C

F

P11

928

315

4 14

15

12

6

14

16

7

8

19

9 19

16

32

35

17

18

40

39


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Neon 2.8 Calcium 2.8.8.2

CaNe2010 20

40

153876503 Chemistry Form 4 Chapter 2 1

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