1.4 Nanoparticles

1nm =

10^-9 m

Size of nanoparticles

1-100nm in size

Bulk material

Not a nanoparticle

The smaller a particle

the larger the surface area to volume ratio

As a cube decreases in size by a factor of 10

Its surface area:volume ratio increases by a factor of 10

Nanoparticles have different properties to bulk materials because

Most atoms are at the surface and they have a high surface area to volume ratio

Uses of nanoparticles

Catalysts, in electronics, in sunscreens.

Advantages of nanoparticles in sunscreen

Better coverage, more effective protection from UV

Disadvantages of nanoparticles in sunscreen

Small enough to enter the bloodstream, could damage cells, could damage the environment

Number of atoms in a nanoparticle

A few hundred atoms

Risks of nanoparticles are unknown

They have not been used for very long

Properties of nanoparticles

Very different to bulk material

Ion

atom that has a positive or negative charge

Polyatomic ion

An ion made of two or more atoms

Ionic compound

A compound that consists of positive and negative ions

Formation of ionic compounds

Metal gives electron(s) to non-metals

Ionic formula

The simplest whole number ratio of the ions which form a neutral ionic compound

Charges in an Ionic Compound

Cancel one another out

Hydroxide ion

OH-

Carbonate ion

CO₃ ^2-

Nitrate ion

NO₃^-

Ammonium ion

NH₄⁺

(s)

Solid

(l)

Liquid

(g)

Gas

(aq)

Aqueous