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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 ?