METALLIC BONDING

• It is between two metals.
• There are fixed positive ions present in the sea of delocalised electrons.
• There is strong electrostatic force of attraction between fixed positive ions and delocalized electrons resulting in metallic bonding.

Properties of Metals

Metals are malleable

• Malleable means that the metals can be hammered into any shape.
• Metals have layered structure and layers can slide past each other by hammering giving metals different shapes.

Metals are ductile

• Ductile means that the metals can be drawn into thin wires.
• Metals have layered structure and layers can slide past each other by hammering giving metals a wire shape.

Metallic Bonding

• Atoms in a metal are arranged in a regular manner and vibrate about fixed positions.
• The outermost electrons move freely, forming a ‘sea of electrons’ enveloping the positive metal ions.

Metals are good conductors of electricity

• Metals have delocalised electrons.
• They are mobile and conduct electricity.
• These mobile electrons or delocalised electrons conduct heat and electricity.

Metals have high melting and boiling points

• There is strong electrostatic force of attraction between fixed positive ions and delocalized electrons.
• Large amount of energy is required to overcome strong electrostatic force of attraction.

METALLIC BONDING

ALLOYS

• Alloys are the mixture of metals with another metal or a non metal which make the metal stronger.
• In metals the particles are arrranged in layers. There is a regular arrangement of fixed positive ions which can slide past each by applying pressure.
• In alloys there is a mixture of metals with another metal or a non metals. Another metal being different in shape and size distort the regular arrangement of the metal lattice.
• As a result the layers of the metal can no longer slide past each other making it strong

Example: Steel is the alloy of iron which is more strong and resistant to corrossion.

NANOPARTICLES

Nanoparticles are the particles that deals with the paricles of size 1 to 100 nm.

KIL- Killing

MET – Metal

MIL -Milo

MIC – Mickey

NAN – Nano

PIC – Pictures

Convert 10 nm to

1. Metre = 10/10⁹m = 10^-8m
2. Micrometer = 10/10⁶m = 10^-5m

SURFACE AREA TO VOLUME RATIO

As the size decreases the surface area to volume ratio Increases.

Therefore Nano particles being very small in size have large surface area to volume ratio making them very useful in Science and Medicine.

Surface area = 6 x side x side m²

= 6 x 1000 x 1000

= 6 10⁶ m²

Volume = side x side x side

= 10⁹m³

SA: Volume = 6 x 10⁶/10⁹ = 6 x 10³ m

Surface area = 6 x side x side m²

= 6 x 1000 x 1000

= 6 10⁴ m²

Volume = side x side x side

= 10⁶m³

SA: Volume = 6 x 10² m

APPLICATIONS OF NANOPARTICLES

MEDICINES

• To kill cancer and tuomour cells
• For drug delievery

CATALYST

• They have large surface area to volume ratio.
• Used in small quantities so highly effective

COSMETICS

• Used in Sunscreen to block sunlight

HOUSEHOLD

• Self cleaning window panes
• Nano particles breaks dirty in the presence of sunshine which is washed away by water while raining.

RISKS OF NANOPARTICLES

• Due to small size can cause difficulty in breathing
• They can accumulate in the envrionment and cause air pollution
• Due to their large surface area a small spark can result in violent explosion making them risky to use.
• They are toxic and cause breathing and respiratory problems.
• Due to their small size they can also cause water pollution and risk the aquation life.

DISCLAIMER

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