Chemical Bonds

METALLIC BOND

Metal to metal bond

Metals LOSE Electrons to gain full outer shells

IONIC BOND

Metal to Non-metal bond

COVELENT BOND

Non-metal to Non-metal

Non-Metals GAIN Electrons to gain full outer shells

NOTE: Group 0 elements - already have full outer shell

Very stable already

Do not form bonds

Unreactive

Metals - release outermost electrons

Metal atoms - become positive ions (as they now have more protons than electrons)

SEA OF DELOCALISED ELECTRONS

Form METALS

Orderly arrangement of positive ions surrounded by a sea of delocalized electrons

Electrons in sea - can move freely carrying ELECTRICTY + HEAT ENERGY

Conducts heat

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Layers of ions - can slide over each other when hammered or stretched

(Electrons 'moved/displaced' by this can still bond)

Malleable

Ductile

STRONG ATTRACTION between POSITIVE IONS and the DELOCALISED ELECTRONS

DEFENITION: strong electrostatic attraction between the closely packed positive metal ions and the sea of delocalised electrons

Strong

High melting point + Boiling Point

MELTING POINT increases as GROUP increases

Group 2

Group 1

1 Outer electron

2 Outer electrons

each atom releases 2 electrons into sea of delocalised electrons

Metal ions: 2+ charge

each atom releases 1 electron into sea of delocalised electrons

Attraction between:

Same number of metal ions (each with 2* the charge compared to group 1 (2+ charge))

2* number of electrons compared to group 1(each with 1- charge)

Metallic Bond - stronger for Group 2 than for Group 1

Metal ions: 1+ charge

electrons TRANSFERED from METAL atom -> NON METAL atom

Metal atom - Lose electrons

Non-Metal atom - Gain electrons

Form negative ions

Form positive ions

Ions - OPPOSITE CHARGES

ATTRACT each other

DEFENITION: Strong electrostatic attraction between oppositely charged ions

Shown using DOT CROSS DIAGRAMS

when drawing diagrams, only draw OUTERMOST shell

MUST DRAW FOR FULL MARKS:

Atoms BEFORE

Electrons transfer

Ions formed

doesn't cause ions to repell

like what happens in IONIC BONDS

High melting + Boiling point

Conducts electricty

Form (GIANT) IONIC STRUCTURES

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Ionic lattice

the regular arrangement of the ions in ionic structures

The oppositely charged ions attract each
other in a regular pattern

SOLID

DISSOLVED/MOLTEN

Ions - free to move/carry charge

Ions - fixed in position + cannot move

Conducts Electricity

Doesn't Conduct Electricity

Free Ions - can bond with water molecules

Soluble in water

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External force applied

Layers slide past one another

same charges repel each other

Brittle

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Orderly array of oppositely charged ions

Forms GIANT COVALENT STRUCTURES

a.k.a giant molecular structures

Forms SIMPLE COVALENT STRUCTURES

'shells' are also known as 'orbitals'

Non-Metals atoms share electrons to gain full outer shells

(As no supply of extra electrons is available)

(As no METALS)

(SINGLE) covalent bond

DOUBLE covalent bond

TRIPLE covalent bond

2 PAIRS of shared electrons

3 PAIRS of shared electrons

1 PAIR of shared electrons

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Drawn as: X-X

Drawn as: X=X

Definition: A very strong bond between 2 non-metal atoms, where atoms share pair/s of electrons to gain full outermost shells

small covalent molecules

STRONG covalent bonds BETWEEN ATOMS

WEAK force of attraction (weak intermolecular
forces) BETWEEN MOLECULES

Easy to break

Low melting + boiling point

Usually liquids/gas at room temp.

LOW density

a.k.a simple molecular structures

NO CHARGES

No free electrons/ions

DOES NOT conduct electricity

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Contain REPEATING structures of STRONG COVELENT BONDS

Diamond

Graphite

Each Carbon forms 4 STRONG covalent bonds to other atoms

All Electrons Used to bond

COULD have free electrons/ions (depending on structure)

Each Carbon forms 3 STRONG covalent bonds to other atoms

Forms HEXAGONAL LAYERS

1 other electron in each atom (not used for covalent bonding)

lost to a SEA OF DELOCALISED ELECTRONS

(As only 3 covenant bonds)

Contrast - 4 in diamond - where all electrons are used in covalent bonding

Strong bonds in all directions

No free electrons

Does NOT conduct heat/electricity

Very Hard

Very high melting (+ boiling) point

Used for: cutting tools + drill bits

WEAK FORCES BETWEEN LAYERS

Layers can slide over each other

Soft

Strong bonds in layers

High melting (+ Boiling) point

SEA OF DELOCALISED ELECTRONS present

very good electrical conductor

Used for: Electrodes

Used for: Lubricant + Pencils

Fullerenes

Large CLASS of allotropes of Carbon

Carbon nano-tubes

Graphene

Allotropes - different forms of the same element

e.g. diamond, graphite, fullerenes, carbon nanotubes are allotropes of Carbon

Made of balls/cages/tubes of carbon atoms

Single layer of a Graphite molecule

Bonded together in HEXAGONAL HONEYCOMB LATTICE

Thinnest material (currently known)

Best (currently known) conductor of heat + electricity

Unreactive

Very strong 100x-300x stronger than steel)

Carbon nano-tubes - type of Fullerene

Layers of graphite rolled into a tube

1 free electron per carbon because of the rolled up structure

Very good electrical conductor

Extremely strong

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Individual atoms of Carbon DONT HAVE THE SAME PROPERTIES as bulk materials (e.g. the bulk material diamond, carbon nano-tubes)

Shown using DOT CROSS DIAGRAMS

when drawing diagrams, only draw OUTERMOST shell

'X' for one atoms electrons, '.' for the other's

'X' for one atoms electrons, '.' for the other's

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Seethrough

Light

Chemical bonding

When atoms bond together

to achieve a full outermost shell/orbital of electrons

By sharing delocalised electrons - strong metallic
bonds are formed between metal atoms

Metal - Higher group

Metal - must lose more electrons to gain full outer shell

Each atom has a greater positive charge - greater number of electrons, so greater difference between number of protons and electrons

More electrons in sea of electrons - release more electrons into sea of electrons per atom

Attraction - between greater number of electrons, and Metal ions with a greater charge

Metallic bond - much stronger here

More difficult/greater energy required to break bonds

Melting point + Boiling point greater

To achieve a FULL outermost orbital of electrons (for both the metals and non-metals)