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How many valence electrons doeach atom have?

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Why do they tend to pair up andshare their valence electrons?

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CovalentBond

Between

non-metalatoms

Sharingof

electrons

Singlebonds Double

bonds

Triplebonds

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The Periodic Table

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A covalent bond is formed when

two atoms share one or more pairsof electrons.

For example: hydrogen atomshave one electron in their outershell.

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There is a strong force ofattraction between hydrogenatoms. This hold them together.

covalent bond

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Lets try this:

The formation of chlorine, Cl2.

Given the proton number ofchlorine atom is 17.

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Electron arrangement of oxygenatom: 2.6Valence electrons = 6So, it needs two electrons to

achieve the octet electron

arrangement.

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How many pairs of electrons are

they sharing?

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The two oxygen atoms share two

pairs of electrons between them.

They form a double bond.

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Now, lets try this:

The formation of bond in

carbon dioxide molecule, CO2

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The proton number for carbon

atom is 6.Electron arrangement is 2.4

To achieve the octet of electrons,

carbon atom needs4

electrons.

C

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Draw :

The formation of bond in

carbon dioxide molecule, CO2

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When two nitrogen atoms cometogether, they share their outer

electrons.

Each nitrogen contributes 3electrons to form three covalentbonds.

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The Lewis structure shows the

formation of the N2 molecule.

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Question 2:

What is the covalent bond

formed when 2 pairs ofelectrons are shared between

the two atoms?

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Question 3:

Draw the electron

arrangement and Lewisstructure of hydrogen

fluoride, HF from hydrogenatom and fluorine atom.

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Question 4:

Draw the electron

arrangement and Lewisstructure of water molecule,

H2O from hydrogen atomand oxygen atom.

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Question 5:

Draw the electron

arrangement and Lewisstructure of nitrogen

molecule, N2.

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Covalent

Bonds

Betweennon-

metalatoms

Sharing of

electrons

Single bondFor example:

Hydrogenmolecule, H2Hydrogenchloride,HCl

Double bondsFor example:

Oxygenmolecule, O2Carbon

dioxide, CO2

Triplebonds

For example:

Nitrogenmolecule,N2

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GOOD LUCKIN YOUR TEST!