nota bab 4 sains t4

8/12/2019 nota bab 4 sains t4

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Chapter 4MATTER AND SUBSTANCES.

4.1 Changes in The States of Matter.

Kinetic theory of matter the properties of matter can be explained by using the kinetic theory of

matter. the kinetic theory matter tries to explain the three states of matter : solid,

liquid, gas : based on the following assumptions :(a) matter is made up of a very fine and discrete particles.(b) the particles of matter constantly move or vibrate.(c) the particles constantly collide against one another and the

walls of the container.(d) forces of attraction exist among the particles in matter, the

forces of attraction become stronger when the particles arepacked closely together.

(e) the higher the temperature , the higher the kinetic energy ofthe particles.

among the examples which support the kinetic theory of matter is thediffusion process.

diffusion is the movement particles in matter from an area of highconcentration to an area of low concentration until both area have thesame concentration.

example if a little bit of perfume is sprayed in area , we can smell it inare ! three metres away because the process of diffusion has occurred this is because the particles of the perfume have moved into the emptyspaces between air particles.

the particles of liquid and gas move randomly and collide against oneanother. (!rownian movement)

temperature influences the kinetic energy content of matter. the higher the temperature, the higher the kinetic energy content of the

particles.


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Pro erties of matter

Pro erties of matter So!i" #i$%i" &as rrangement of

particles

rranged

closely,compactly andorderly in fixedpositions. "hereis very littleempty spacebetween oneparticle andanother.

#iquid particles

neatly norcloselyarranged. "hereare emptyspaces amongthe particles.$ost of theparticles keepcontact with oneanother.

%as particles

are not neatlyarranged andare further apartfrom oneanother.

$ovement of particles &articles do notmove freely andonly vibrate attheir fixedpositions.

&articles moveslowly in arandom manner.

&articles movefast in a randommanner and inall directions.

'orces of attractionbetween particles

ery strong ot very strong ery weak

*nergy content ery low $oderate ery high+hape 'ixed 'ollowing theshape of thecontainer

'ills up thewhole container

olume 'ixed 'ixed ot fixedompression ot

compressibleery difficult to

compress*asilycompressed

Changes in the state of matter. heat is the energy that determine the movement particles in matter. if the temperature of matter increases, particles will get higher kinetic

energy to move faster. consequently, changes in the state of matter occur through the process of

heating or cooling, i.e. when heat energy is absorbed or releases from thematter.

when heat is supplied, the state of matter will change from solid to liquid,and finally to gas.


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take changes in the state of matter which take place when heat is suppliedare melting, boiling, sublimation

when heat is released the state of matter will change from gas to liquidand finally to solid.

the changes in the state of matter which take place when heat is released

are free-ing, condensation, sublimation. sublimation occurs when the state of matter changes from solid to gas or

vice versa without going through the liquid stage.

Melting

when a solid is heated, heat is absorbed by its particles.particles possesses more kinetic energy and vibrate faster.at melting point, particles in the solid have enough energy to overcomethe forces of attraction between particles and to move freely.the solid melts and changes to become liquid.

Boiling

when liquid is heated, heat energy is absorbed by its particles.the liquid particles have more kinetic energy and move faster.at boiling point, the energy possessed enable the particles to overcomethe forces of attraction between the particles and they released as gas.

Sublimation


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when a solid is heated, its particles gain more energy and move faster.the particles in solid separate from solid lattice and release as gas intothe air.

Freezing

when liquid is cooled, its particles lose energy and are held together bystrong forces of attraction between particles.this cause liquid particles not able to move freely and they only vibrate intheir positions

the liquid free-es to become solid.

Condensation

when gas is cooled, its particles lose energy and are held together by

forces of attraction between particles.this causes the particles to moves slowly.the distance between gas particles becomes closer.the gas changes to liquid.

Sublimation

when gas is cooled, its particles lose energy and are held together bystrong forces of attraction between particles.this cause the particles to move very slowly.the distance between gas particles becomes closer.


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the gas changes to solid.

Changes in the state of matter involving heat change

4.' Str%ct%re of Atoms.

Atoms all matter consists of tiny units called atoms. atom is a basic unit of all matter. atoms cannot be seen with an ordinary microscope because they are so

tiny. an atom consists of a nucleus in the centre surrounded by electrons. electrons move around the nucleus following a certain orbit.

structure of an atom

S%(atomic artic!es an atom is made up of particles that are even smaller called subatomic

particles.

+olid

%as #iquidboiling

(heat absorbed)

condensation(heat released)

free-ing(heat released)

sublimation(heat absorbed)

melting(heat absorbed)

sublimation(heat released)

nucleus

electron

orbit


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there are three types of subatomic particles : protons neutrons electrons protons and neutrons from the nucleus in the centre of an atom. electrons move around the nucleus at high speed. the mass of an atom is concentrated in its nucleus.

subatomic particles in an atom

Com arison (et)een s%(atomic artic!es

S%(atomicartic!e

Sym(o! Position in atom Re!ati*echarge

Re!ati*emass

Mass in gram

&roton p ucleus /0 0 0.123 x 04 536

eutron n ucleus 4 0 0.127 x 04 536

*lectron e $oves around nucleus 50 080964 .042 x 04 539

comparison between subatomic particles

atoms of any element are neutral because the number of electrons in anatom are the same.

in a neutral atom, the total positive charges in the nucleus are the same asthe total negative charges from the electrons which orbit around thenucleus.

Atom N%m(er of rotons N%m(er ofe!ectrons

N%m(er of ne%trons

;ydrogen 0 0 4;elium 3 3 3

arbon 1 1 1+odium 00 00 03

number of subatomic particles in different atoms

ions are atoms or particles which have charge. ions are produced when the number of protons (positive charge) and the

number of electrons (negative charge) are not balanced.

electron (5)

proton (/)neutron

nucleus


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positive ions are particles that are positively charged. positive ions are produced when the number of protons is more than the

number of electrons. negative ions are particles that are negatively charged negative ions are produced when the number of electrons is more than the

number of protons.4.+ Proton N%m(er an" N%c!eon N%m(er in Atoms of E!ements.

Proton n%m(er an" n%c!eon n%m(er proton number is the number of protons in an atom of an element. elements can be differentiated by referring to their proton number. in a neutral atom, the proton number also refers to the number of

electrons in that atom.

nucleon number is the total number of protons and neutrons in an atom ofan element.

the number of neutrons in an atom can be calculated if its proton number

and nucleon number are known.

in a neutral atom :

table below shows that atoms of different element possesses differentnumbers of protons and electrons.

proton number < number of protons < number of electrons in a neutral atom

nucleon number < number of protons / number of neutrons < proton number / number of neutrons

number of neutrons < nucleon number proton number < nucleon number number of protons

a) nucleon number < number of electrons / number of neutronsb) number of neutron < nucleon number / number of electrons


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atoms of certain elements can represented by the following symbol :

,soto es are atoms of the same element that possesses the same number of

protons but different number of neutrons. can also be defined as atoms of the same element with the same proton

number but different nucleon number. isotopes of the same element possess the same chemical properties.

the physical properties of isotopes are different.E!ement ,soto e N%c!eon

n%m(er Protonn%m(er

N%m(erof

rotons

N%m(erof

ne%trons

N%m(erof

e!ectrons;ydrogen ;ydrogen50 0 0 0 4 0

;ydrogen53 3 0 0 0 0;ydrogen5= = 0 0 3 0

>xygen >xygen501 01 9 9 9 9>xygen502 02 9 9 9>xygen509 09 9 9 04 9

arbon arbon503 03 1 1 1 1arbon50= 0= 1 1 2 1

arbon506 06 1 1 9 1examples of isotopes

E!ement N%m(er ofrotons

N%m(er ofe!ectrons

N%m(er ofne%trons

Protonn%m(er

N%c!eonN%m(er

;ydrogen 0 0 4 0 0;elium 3 3 3 3 6#ithium = = 6 = 2

!eryllium 6 6 7 6!oron 7 7 1 7 00

arbon 1 1 1 1 03itrogen 2 2 2 2 06

>xygen 9 9 9 9 01'luorine 04 0

eon 04 04 04 04 34

06

2

nucleonnumber

proton number symbol of

element

number of neutron < 06 2 < 2


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PEN&E#ASAN UNSUR-UNSUR DA#AM ADUA# BERKA#A

PEN&E#ASAN UNSUR-UNSUR DA#AM ADUA# BERKA#A

?nsur5unsur disusun dalam @adual !erkala mengikut s%s%nan nom(orroton sema/in mening/at.

ombor proton meningkat daripada daripada kiri ke kanan dan daripadaatas ke bawah @adual !erkala

+etiap laAur tegak dikenali sebagai kumpulan +etiap baris melintang dikenali sebagai kala

0 3 = 6 7 1 2 9 04 00 03 0= 06 07 01 02 09

B?$&?#

0

3 = 6

7 1

2

B #


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?nsur5unsur dalam kumpulan yang sama mempunyai sifat kimia yangsama

+ifat fi-ik dan sifat kimia unsur5unsur beransur5ansur berubah merentasikala

Ci dalam @adual !erkala, terdapat 09 kumpulan dinomborkan daripada 0

hingga 09 dan 2 kala dinomborkan dariapda 0 hingga 2. Bumpulan 0 (logam alkali) dan kumpulan 3 (logam alkali bumi) terdiri

dariapda logam5logam yang sangat reaktif. ?nsure5unsur dalam kumpulan 02 adalah bukan logam dan dikenali

sebagai halogen. Bumpulan 09 terdiri daripada gas5gas lengai yang secara kimianya stabil

dan tidak reaktif. ?nsure5unsur yang terletak di antara kumpulan 3 dan 0= adalah unsure

logam peralihan

Ke entingan a"%a! Ber/a!a

Bepentingan pengelasan unsur5unsur dalam @adual !erkala adalahuntuk :(a) $embantu kita untuk mengkaAi unsur5unsur dalam tertib dan

teratur dan secara bersistematik(b) $embantu kita untuk mengetahui sifat5sifat unsur5unsur

dengan mudah kerana unsur5unsur dengan sifat yang sama diletakkandalam kumpulan yang sama

(c) $embantu kita untuk meramalkan sifat5sifat dan kegunaanunsur dengan meruAuk kepada kedudukan unsur5unsur di dalam

@adual !erkala


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S,0AT-S,0AT BA AN BERDASARKAN KEPADA KANDUN&AN 2ARA -2ARA

"erdapat tiga Aenis bahan5bahan atoms are the tiniest particles in an element. molecules are groups of atoms Aoined together. a molecule consists of two or more atoms ions are particles which carry positive or negative charges.

Atomic s%(stances. are substances that consist of only atoms. all metals are atomic substances. (ex : iron, lead, sodium)

the atoms are in atomic substances are packed closely, compactly andarranged orderly in fixed positions. the atoms in atomic substances are held together by a strong chemical

bond.

arrangement of atoms in metal

Mo!ec%!ar s%(stances. molecules are the simplest particles found in molecular substances. nitrogen, sulphur dioxide and iodine are examples of molecular

substances. molecular substances are made up of molecules which have two or more

atoms of the same type. for example, two oxygen atoms combine to form one oxygen molecule.

atom


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molecular substances can also be made up of two or more atoms ofdifferent types.

for example, one nitrogen atom combines with three hydrogen atoms toform one ammonia molecule.

ammonia molecule consists of one nitrogen atom and three hydrogen atoms.

molecules are made up of non5metal atoms held together by a strongcovalent bond.

however, the forces of attraction between molecules in a molecularsubstance are relatively weak . the weak forces between molecules inmolecular substance are called an der Daals forces.

,onic s%(stances. are formed when atoms of metals combine with atoms of non5metal

through chemical bonding to form compounds. sodium chloride, lead (EE) bromide and magnesium oxide are examples of

ionic compounds. positive ion and negative ion attract one another. forces of attraction between ions of opposite charge are called

electrostatic attraction force.

Physica! ro erties of atomic3 mo!ec%!ar an" ionic s%(stances.

Physica! ro erty Atomic S%(stance Mo!ec%!ar S%(stance ,onic S%(stances&hysical state atroom temperature

+olid except mercury +olid : Eodine#iquid : Dater %as : >xygen

+olid

rrangement ofparticles

&acked very closely +olid : &acked#iquid : ot packed%as : 'ar apart

&acked veryclosely

'orces of attraction ery strong Deak ery strong

; ;

;

sodium ion (/)

chloride ion (5)


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between particles$elting point andboiling point

;igh #ow ;igh

*lectricalconductivity

ll metals and carbon(graphite)

Coes not conduct electricity onductselectricity in moltenstate

+olubility Coes not dissolve inanything $ost of them dissolve inorganic solvent $ost of themdissolve in water 4. Pro erties an" Uses of Meta!s an" Non-Meta!s.

Meta!s an" Non-Meta!s. elements can be classified into metals and non5metals. ex : iron, aluminium, -inc, copper, lead, tin ,and gold. carbon, iodine, bromine, sulphur, phosphorus, and chlorine are examples

of non5metals. all metals exist in a solid state at room temperature except mercury.(liquid) non5metals exist in a solid, liquid, or, gaseous state at room temperature.

Physica! ro erties of Meta!s an" Non-Meta!s.

Meta!s Differences Non-meta!s;ave shiny surfaces #uminosity ;ave dull surfacesCuctile Cuctility ot ductile*asily rolled orhammered into foils orthin sheets

$alleability annot be forged

;igh "ensile strength #ow%ood conductor ofelectricity

*lectrical conductivity Co not conduct electricityexcept carbon

%ood conductor of heat ;eat conductivity &oor conductor of heat;igh $elting point and boiling

point#ow

;igh Censity #ow+olid (except mercury inliquid state)

+tate of matter at roomtemperature

+olid, liquid, or gas

Uses of Meta!s an" Non-Meta!s in "ai!y !ife.

Meta! Physica! Pro erty UseEron ;igh tensile strength Failway tracks and

framework for brid ges luminium #ight, good conductor of electricity

and heatBitchen utensils and electriccables

opper Cuctile and malleable, goodconductor of electricity and heat

*lectrical wires

"in Co not rust *lectroplating of food cans


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%old Coes not rust and is shiny @ewellery#ead Cuctile, malleable able casing

Non-meta! Physica! Pro erty Usearbon (graphite) +oft and smooth, good

conductor of electricity#ead of pencils, used asthe electrodes inelectrolysis and in dry cell

arbon (diamond) ;ard Crill bits for cutting stoneeon gas and

krypton&oor conductor of heat #ights used for billboards

hlorine cidic ?sed to kill germs indrinking water

4.5 Metho"s of S%(stance P%rification.

Characteristics of %re s%(stances. pure substances do not contain any impurities. pure substances always have specific melting (free-ing) point and boiling

point. for example : pure water boils at 044 o and ice melts or free-es at 4 o at

normal atmospheric pressure. pure iron melts at 0764 o and boils at3944 o at normal atmospheric pressure.

any impurities added to a pure substance will increase the boiling point orlower the free-ing (or melting) point of that substance.

for example : water that is added with salt will boil at a temperature higherthan 044 o and will free-e at a temperature lower than 4 o .

Metho" of s%(stance %rification. impurities can be separated from pure substances. the process of separating impurities form a substance is called

purification. there are two methods of purification :

distillation

crystallisation

Distillation


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is used to obtain pure liquid from a solution which contains impurities. this method is used to separate two liquids (liquid mixture) that :

0. dissolve one another 3. do not react=. possess different boiling points

distillation involves the process of heating liquid until it becomes vapour(gas)

this vapour is then condenses to become pure liquid.

distillation can be conduced to separate mixtures of substances such aspurifying alcohol from a mixture of alcohol and water and also purifyingwater from a mixture of water and salt.

the substance with a lower boiling point boils and vaporises earlier. then the gas (vapour) will go through condensation to form the pure

product of distillation.

Crystallisation crystallisation is a purification method carried out to obtain pure crystals

from a saturated solution of the substances. example : purification of salt from its saturated solution. saturated solution is a solution containing maximum quantity of solute.

A !ication of P%rification Metho". distillation and crystallisation are often used to obtain pure substances. these purification methods have produced many substances for our daily

needs. examples of the application of distillation :

(a) breaking crude petroleum into its fractions such as petrol,kerosene and diesel to produce fuels and to make variouskinds of plastic material.

(b) production of pure water or distilled water for the preparationof chemical solution, medicine, as well as food andbeverages.

#iquid %as #iquidboiling condensation


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(c) obtaining pure ethanol from fermentation of sugar solutionand yeast.

examples of the application of crystallisation :(a) production of salt from seawater.(b) preparation of white sugar crystals from sugarcane Auice.

nota bab 4 sains t4

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