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SREE NARAYANA TRAINING COLLEGE SREEKANDESWARAM POOCHACKAL

B.Ed 2014-15KERALA UNIVERSITY

Submitted By, SETHULEKSHMI K R

PHYSICAL SCIENCE REG NO: 18214383019

Submitted To, MRS.LINI MOL.K.S Faculty in Physical science department SNTC Poochakkal

CHEMICAL BONDING

A chemical bond is an attraction between atoms that allows the formation chemical substances that contain two or more atoms . The bond is caused by the electrostatic force of attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction.

A chemical bond forms when the potential energy of the bonded atoms is less than the potential energy of the separate atoms

Have to consider following interactions: nucleus-to-nucleus repulsion electron-to-electron repulsion nucleus-to-electron attraction

TYPES OF BONDS

Types of Atoms Type of Bond Bond

Characteristicmetals to nonmetals

Ionicelectronstransferred

nonmetals tononmetals

Covalentelectrons shared

metal tometal

Metallicelectronspooled

8

TYPES OF BONDING

Tro, Chemistry: A Molecular Approach

IONIC BONDS

When metals bond to nonmetals, some electrons from the metal atoms are transferred to the nonmetal atoms

–Metals have low ionization energy, relatively easy to remove an electron from–Nonmetals have high electron affinities, relatively

good to add electrons to

Electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

COVALENT BOND“Bond formed by the sharing of electrons”

Tro, Chemistry: A Molecular Approach 12

Nonmetals have relatively high ionization energies, so it is difficult to remove electrons from them

When nonmetals bond together, it is better in terms of potential energy for the atoms to share valence electrons Potential energy lowest when the electrons are between the

nuclei Shared electrons hold the atoms together by attracting nuclei of

both atoms

Two atoms share one or more pairs of outer-shell electrons

Oxygen Atom Oxygen Atom

Oxygen Molecule (O2)

Tro, Chemistry: A Molecular Approach

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1. Single Covalent BondsTwo atoms share a pair of electrons

2 electronsOne atom may have more than one single bond

F••••

•• • F•••••••

F••••

•• ••

••F

•••• HH O••••••

••

H•H• O••

• •

••

F F

Tro, Chemistry: A Molecular Approach

15

2.Double Covalent Bond

Two atoms sharing two pairs of electrons 4 electrons

O•••• O

••••

••••

O••

• •

••O

••• •

••

O O······ ··

Tro, Chemistry: A Molecular Approach

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3.Triple Covalent Bond

Two atoms sharing 3 pairs of electrons 6 electrons

N••

• •

•N

••• •

•N••

••••••••

N

N N····