The stable elementsThe stable elements

Ionic bondingIonic bonding

Metalic bondsMetalic bonds

Covalent bondingCovalent bonding

Many nature elements are unstable and tend to form compounds, except

the noble gas The are no nature noble gas compounds found

The noble gases are stable elements

Ele-ments

Number of electron in atomic shells

K L M N O P

2 He 2

10Ne 2 8

18Ar 2 8 8

36Kr 2 8 18 8

54Xe 2 8 18 18 8

86Rn 2 8 18 32 18 8

The outer (valence) shell of noble gas atom has 8 electrons (except He : 2 electrons)

The 8 electrons form 4 electron pairs and make stability

The atom with 8 valence electrons like noble gas is stable (octet rule) > 2 electron for little atom (duplete rule)

So the unstable elements trends to reach noble gas configuration by :

CHEMICAL BONDING

GN Lewis purposes the dot symbol of valence electron

Examples :H C F

Be N Ar

B O1 dot represent a valenceelectron

to explain chemical bonding process

conceptconcept

examplesexamplesexercisesexercises summarysummary Home

assigment

Home assigment

CovalentcoordinateCovalent

coordinate

SingleDoubleTripplebond

SingleDoubleTripplebond

PolarCovalent

bond

PolarCovalent

bond

2 hydrogen atoms can form H2 molecule by chemical bonding

2 hydrogen atoms can form H2 molecule by chemical bonding

1H + 1H H H

H H H H H2Bonding electron pair

• Each hydrogen atom contributes an electron to form bonding electron pair that can be shared both atoms. This chemical bonding named COVALENT BONDING

• Each hydrogen atom contributes an electron to form bonding electron pair that can be shared both atoms. This chemical bonding named COVALENT BONDING

H

H

Example

17Cl : 2 8 7

HCl

NH3

H H H2

Cl2 :

Cl Cl

Cl-Cl

H Cl

H N

Non bonding electron pair(lone pair electrons)

Examples Oxygen molecule O2

8O : 2 6

Write the diagram valence electrons to explain chemical bonding in CO2 molecule!

6C : 2 4O O

O ODouble bonds

C OO

O OC

Examples nitrogen molecule N2

7N : 2 5

Examples nitrogen molecule N2

7N : 2 5

What about covalent bonding in HCN molecule ?

What about covalent bonding in HCN molecule ?

N N

N Ntripple bonds

C N

C N

H

Hsingle bonds

tripple bonds

1. Write the Lewis diagram of NH3, H2O, and CS2 molecules !

2. Predict the chemical formula of compound formed beetwen 15X and 17Y, when they obey octet rule!. Use the Lewis diagram to explain!

3. How many single, double, or tripple covalent bond in C2H2 molecule ?

The covalent bonding is chemical bonding resulted by sharing electron pairs that is formed by electrons contributing from atoms.

The covalent bonding should be single, double, or tripple bond, form molecular compound.

Covalent bond

Formed from sodium and chlorineNa Cl

Unstable elements2 8 1 2 8 7

NaCl

stable compound

11Na : 2 8 1 loses 1 e to reach 2 8 (Ne)

Na atom changes to be Na+ ion 17Cl : 2 8 7 attract/gain 1 e to reach 2 8

8 (Ar) Cl atom change to be Cl- ion

Both ions Na+ and Cl- attract with electrostatic force form NaCl compound which has strong chemical bonding.

Chemical bonding is attractive force that Chemical bonding is attractive force that exists beetwen certain atoms in a exists beetwen certain atoms in a substance.substance.

The chemical bonding that resulted from The chemical bonding that resulted from the attractive form of oppositely charge the attractive form of oppositely charge ion named IONIC BONDINGion named IONIC BONDING

Positive ion will be formed when an atom Positive ion will be formed when an atom remove it’s valence electronremove it’s valence electron

Negative ion will be formed when an Negative ion will be formed when an atom gain electronatom gain electron

Na Cl

Na+ Cl_

NaCl

Explain the chemical bonding beetwen magnesium and

fluorine !

12Mg : 2 8 2 remove 2 e > Mg2+

9F : 2 7 gain 1 e > F-

1 Mg atom bonds 2 F atoms form MgF2

Mg2+ + 2 F- -> MgF2

Mg F

Mg2+ F_

MgF2

_

Mg2+ + 2 F-

Explain the chemical bonding in formation of kalsium oxide (CaO)

What is the compound formed beetwen potassum and oxigen ? What about it’s chemical bond formation ?

IONIC BONDING is the chemical bonding that resulted from the attractive

force of oppositely charge ion.

The ions is formed by removing or gaining electrons of an atom

Aluminium metal and sulphure can form Aluminium metal and sulphure can form the aluminium sulphide. the aluminium sulphide. Write the electron configuration Al and SWrite the electron configuration Al and SHow do the Al and S atom reach the How do the Al and S atom reach the “octet” configuration ?“octet” configuration ?Explain the chemical bond formed Explain the chemical bond formed beetwen Al and Sbeetwen Al and SWhat is the chemical formula of What is the chemical formula of aluminium sulphide ?aluminium sulphide ?