FORMATION OF COMPOUNDS

Chemical bond
•Atoms of other elements tend to achieve the stable electron arrangement.
•Can be formed by the transfer of electron or sharing electrons.


Ionic bonds
•Are formed through the transfer of electrons between atoms of metal and non-metal.
•Metal – donate electron / non-metal – accept electron
Formation of ions
•Anion : an atom that accepts electrons forms a negative ion.
•Cation : an atom that donates electrons forms a positive ion.


Example:
Formation of magnesium oxides
The formation of ionic bonds in magnesium oxide, MgO, is explained as follows:
•The electron arrangement of magnesium, Mg, atom is 2.8.2.
•Magnesium, Mg, atom donates its two valence electrons to form magnesium ion.
•Magnesium ion achieve a stable electron arrangement ( octet electron arrangement ).
•Electron arrangement of oxygen is 2.6.
•Oxygen, O, atom receives two electrons to form oxide ion.
•Oxide ion achieves a stable electron arrangement ( octet electron arrangement ).
•Strong electrostatic force pulls the magnesium ion and oxide ion together.
•An ionic bond is formed.

COVALENT BOND

Covalent bond
•The chemical bond formed through the sharing of electrons between two non-metal atoms.
Single bond
•Covalent bond formed when a pair of electron is shared between atoms.
Double bond
•The type of covalent bond formed through the sharing of two pairs of electrons between two non-metal atoms.
Triple bond
•The type of covalent bond formed through the sharing of three pairs of electrons between two non-metal atoms.

example:
THE FORMATION OF TETRACHLOROMETHANE ( SINGLE BOND )

The formation of single covalent bond in tetrachloromethane molecule can be described as follows:
•Each chlorine, Cl, atom has an electron arrangement of 2.8.7 while a carbon, C, atom has electron arrangement of 2.4.
•The outermost shell of chlorine ,Cl, atom and a carbon, C, atom lack one electron and four electron respectively to achieve a stable electron arrangement.
•One carbon, C, atom shares electrons with four chlorine, Cl, atoms.
•Each carbon, C, atom contributes four valence electrons while each chlorine, Cl, atom contributes one valence electron for sharing.
•Each chlorine, Cl, atom achieves the electron arrangement of 2.8.8. Each carbon, C, atom achieves an electron arrangement of 2.8.
•Each atom in the tetrachloromethane molecule achieves a stable electron arrangement.
•Four single covalent bonds are formed.

Characteristic Of Ionic Bond.
Element
•Between metals ( Group 1,2 & 13 ) and non-metal.
Bond formation
•Electron is released by metal atoms and received by non-metal atoms (electron transfer).
Type of particle formed
•Metal – positive ion
•Non-metal – negative ion
How to predict the formula
•Determine the charge of ion.


Characteristic Of Covalent Bond
Element
•Between non-metal and non-metal (Group 14,15, and 16)
Bond formation
•Pairs of electrons are shared by the same or different non-metal atoms.
Type of particle formed
•Neutral molecule
How to predict the formula
•Determine the number of electrons needed to achieve duplet/octet.


The Physical Properties Of Ionic Compound
Melting and boiling points.
•High because positive ion and negative ion are pulled.
•Large amount of energy is needed to overcome it.
Electrical energy.
•Cannot conduct electricity when in solid state but able to conduct electricity in molten or liquid states.
Water solubility
•Most are soluble in water but not in organic solvent
Volatility
•Non-volatile because ion are pulled by strong electrostatic forces.



Physical Properties Of Covalent Compound.
Melting and boiling points
•Low because only a small amount of heat is needed to overcome the weak forces of attraction between molecules.
Electrical conductivity
•Cannot conduct electricity in both molten and liquid and are not electrolyte.
•Covalent compounds are neutral molecules.
Water solubility
•Most are insoluble in water but soluble in organic solvent.
Volatility
•Highly volatility because of the weak “Van der Waals” force.

PERIODIC TABLE OF ELEMENTS

The Periodic Number Of Element
#The number of shells occupied with electros in its atom

Group 18 Element

# insoluble in water # low density

# cannot conduct electricity # colourless & unreactive

# poor conductor of heat # exist in monoatomic gases

Uses Of Group 18 Elements

• Helium # to cool the coils in body scanners in medical field
• Neon # advertising light on billboard and television tubes
• Argon # used in filament bulb & provide an inert atmosphere for welding at high temperature.
• Krypton # used in laser to repair retina & to fill photographic flash lamps.
• Radon # used to treat cancer patients
• Xenon # used in bubble chamber in atomic and making rlrctrin tubes and stroboscopic

GROUP 1 ELEMENTS

Going Down Group 1

• atomic radius increase
• density increase
• melting and boiling points decrease

GROUP 17

Physical properties

• poor conductor of heat # poor electric conductor
• low melting & boiling points # called as halogen (salt former).

1. Fluorine # pale yellow gas
2. Chlorine # greenish-yellow gas
3. Bromine # reddish-brown liquid
4. Iodine # purplish-black solid

Going Down Group 17

• increase in size # higher density
• less reactive # increase the atomic radius
• Increase melting & boiling points # decrease the force of attraction

Elements In A Period

Across Period 3

• the proton number increasesby one unit from one element to the next element,
• all atoms of the elements have three shells occupied xith electron.
• the number of valemce electrons each atom increases from 1 to 8.
• all the elements exist as solid except chlorine and argon which are gases.
• the atomic radius of elementsdecreases.
• the electronegativity of element decrease.

Uses Of Semi-metal In Industries

• Silicon and germanium are used in semiconductors

- enable to surf internet and watch television.

• Semiconductors are used to make diods and transistors.

TRANSITION ELEMENTS

• Transition elements show different oxidation numbers in their compounds.
• Transition elements form coloured ions or compounds.
• Their compounds are useful catalysts.

Uses In Industries

• Iron is used as a catalysts in the manufacture of ammonia in Haber Process.
• Platinum is used as a catalyst in the Ostwald a process of manufacturing of nitric acid.
• Nickel is used as a catalyst in the manufacture of margerine.
• Vanadium(V) oxide is used as a catalyst in the Contact Process for the manufacturing of sulphuric acid.

RELATIONSHIP BETWEEN NUMBER OF NUMBER OF MOLE,MASS,NUMBER OF PARTICLES AND VOLUME OF GAS

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CHEMICAL FORMULAE AND EQUATIONS

A.RELATIVE ATOMIC MASS AND RELATIVE MOLECULAR MASS



RELATIVE ATOMIC MASS:The average mass of one atom of the element when compare

with 1/12 of the mass of an atom carbon-12.

RELATIVE MOLECULAR MASS: The average mass of the molecule when compared with

1/12 of the mass of one atom of carbon-12



B.THE MOLE AND THE NUMBER OF PARTICLES



What is a mole?

:A mole is an amount of substance that contains as many particles as the number of atoms in exactly 12g of carbon-12.

Avogadro Constant: the number of particles in one mole of a substance.

: one mole of substances contain 6.02*10^23 particles.



C.THE MOLE AND THE MASS OF SUBSTANCES


:The mass of one mole of any substances is called its molar mass
:The value of molar mass of an element is equal to its relative atomic mass.





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THE STRUCTURE OF THE ATOM

ATOM:The smallest particle of an element that can participate in a chemical
reaction.

MOLECULE:A group of two or more atoms which are chemically bonded together .

ION: A positively-charged or negatively-charged particle.

THE KINETIC THEORY OF MATTER

SOLID

• Has fixed volume and shape
• Cannot be compress
• The particles are packed closely together in an orderly manner
• There are strong forces between the particles.
• The particles can only vibrate and rotate about their fixed positions

LIQUID

• Has fixed volume
• It does not have a fixed shape but takes the shape of the container
• Cannot be compress easily
• The particles are packed closely together but not in orderly arrangement
• The particles are held together by strong forces but weaker than the forces in a solid
• The particles can vibrate, rotate and move throughout the liquid.They collide against each other.

GAS

• Does not have fixed shape or volume
• Can be compressed easily
• The particles are very far apart from each other and in random motion
• Weak forces between particles
• Can vibrate, rotate and move freely.The rate of collision is greater than liquid.

ISOTOPES AND THEIR IMPORTANCE

WHAT IS ISOTOPES?

: Isotopes are atoms of the same element with different number of neutrons

USES OF ISOTOPES

• Cobalt-60 = Used in Radiotheraphy for the treatment of cancer
• Gamma Rays of Cobalt-60 = Used to destroy bacteria in food without changing the quality of food.
• Carbon-14 =used to estimate the age of fossils and artefacts
• Phosphorus-32 = study the metabolism of phosporus in plants
• Iodine-131 = used to diagnose thyroid glands diseases

INTRODUCTION TO CHEMISTRY

WHAT IS CHEMISTRY?

• word chemistry originates from the arabic word 'al-kamiya' means the art of transforming metal
• the study of composition, structure, properties, and interaction of matter

CHEMISTRY RELATED CAREERS

• Doctor
• Environmental Scientist
• Cosmetic Scientist
• Food Technologist
• Forensic Scientist
• Geologist
• Pharmacist
• Pathologist
• Nutritionist
• Laboratory Technician
• Horticulturalist
• Chemical Engineer
• Biochemist
• Bacteriologist
• Aqua Culturist

SCIENTIFIC METHOD

:A systematic method used to solve problems in science.

1. making observation
2. making inference
3. identifying problems
4. making hypothesis
5. identifying variables
6. controlling variables
7. planning an experiment
8. collecting data
9. interpreting data
10. making conclusion
11. writing report