Ionic & Covalent Bonding

Chapter 5 Section 2

Why do atoms want to bond?

• Atoms want to be STABLE.–Goal: to have an electronic structure close to

that of a Noble Gas.• The type of bond that atoms form affects the

substances properties.

FK

FK

FK

FK

FK

FK

FK

FK

Fluorine now has a total of 10 electrons = Neon

Potassium now has a total of 18 electrons = Argon

+ -

There are 3 types of bonding:

1.Ionic2.Covalent3.Metallic

Ionic BondsBonds formed between

oppositely charged ions by a transfer of electrons.

Formation of Ions from MetalsIonic compounds result when metals react with

nonmetals Metals lose electrons to match the number of

valence electrons of their nearest noble gasPositive ions form when the number of electrons are

less than the number of protons: Cation

Li + Group 1 metals ion 1+

Mg 2+ Group 2 metals ion 2+

Al 3+ Group 13 metals ion 3+

Nonmetals gain electrons to match the number of valence electrons of their nearest noble gas.Negative ions form when the number of electrons are more than the number of protons: Anion

Cl - Group 17 metals ion 1-

S 2- Group 16 metals ion 2-

P 3- Group 15 metals ion 3-

Ionic compounds will conduct electricity when melted or dissolved in water. Ionic compounds have a very high melting point.

Formation of Sodium Ion

Sodium atom Electron Exchange Sodium ion Na minus 1e Na +

2-8-1 2-8 ( = Neon) (2 in 1st level, 8 in 2nd (2 in 1st, 8 in 2nd) level, 1 in 3rd level)

11 p+ 11 p+

11 e- 10 e-

0 1+

Group 1

Group2

Group13

Group14

Group15

Group16

Group17

Group18

-1-2

-3 -4Or

+4+3

+2+1

0

Covalent BondsBond formed by the sharing of

electrons.

• Covalent bonds are formed between two nonmetals.

• Covalent compounds usually have low melting points.

• Electrons can be shared equally (nonpolar) or unequally (polar).

• The number of electron pairs shared can also vary.

when electrons are shared equally

NONPOLAR COVALENT BONDS

ClCl

Cl Cl

Cl Cl

Cl Cl

Cl ClThis is called a SINGLE BOND

(The sharing of one pair of electrons = 2 electrons)

OO =This is an example of a DOUBLE BOND

(The sharing of two pairs of electrons = 4 electrons)

OO

This is called a TRIPLE BOND(The sharing of three pairs of electrons = 6

electrons)

when electrons are shared but shared unequally

POLAR COVALENT BONDS

• In this type of bond, electrons are attached to the nucleus of one atom more than the other.– Therefore, unequal sharing occurs.

• Usually, electrons are more attracted to atoms of elements that are located to the right and closer to the top of the periodic table.

METALLIC BONDS

• The bonding of a metal to a metal.• The attraction between one atom’s nucleus

and another atom’s electrons which packs the atoms closely together.

• Properties:– Flexible = can stretch and bend without breaking.• Metallic Bonds are flexible because their atoms can

slide past each other without breaking.– Good conductor of electricity.

• Atoms are free moving– This is why metallic bonds can conduct electricity.

• Electrons in the outer level overlap.

Polyatomic Ions• Have both Covalent and Ionic bonds.– This means that the bond is technically

Covalently bonded that have either LOST or GAINED electrons.

• Polyatomic anions are made of Oxygen.–ate: ions with one or more Oxygen.– ite: ions with 1 less Oxygen.

-ate

SO -2

4

SULFATE

-ite

SO -2

3

SULFITE

• Transition Metals have many different charges.

• Roman numerals in parenthesis following a cation to show the charge. – i.e. • Copper (I) ion• Copper (II) ion• Titanium (II) ion• Titanium (III) ion • Titanium (IV) ion