Nanoparticles
Tiny particles which are between 1 and 100 nanometres (nm) in size. are structures, 1-100 nanometres (nm) in size, that usually contain only a few hundred The smallest part of an element that can exist.. This means that nanoparticles are around 100 times larger than atoms and simple A collection of two or more atoms held together by chemical bonds..
Buckminsterfullerene, with the formula C60, is a nanoparticle:
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Small size
Some of the The characteristics of something. In chemistry, chemical properties include the reactions a substance can take part in. Physical properties include colour and boiling point. of nanoparticles depend on their very small size.
Worked example
A zinc oxide nanoparticle has a diameter of 32 nm. The diameter of a zinc atom is 0.28 nm. Estimate how many times larger the nanoparticle is compared to a zinc atom.
To help with this estimate, round each number to 1 Giving a number to a specified number of significant figures is a method of rounding. For example, in the number 7483, the most significant, or important, figure is 7, as its value is 7000. To give 7483 correct to one significant figure (1 sf), would be 7000. To 2 sf, it would be 7500.:
30 nm and 0.3 nm
Number of times larger 鈮 \(\frac{\textup{30}}{\textup{0.3}}=~\textup{100}\)
The nanoparticle is about 100 times larger than the zinc atom.
Surface area to volume ratios
Some of the properties of nanoparticles depend on their large The total area of all sides on a 3D shape. to The volume of a three-dimensional shape is a measure of the amount of space or capacity it occupies, eg an average can of fizzy drink has a volume of 330 ml. ratios. For solid substances, the smaller its A general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules., the greater the surface area to volume ratio.
Worked example
A cube-shaped nanoparticle has sides of 10 nm. Calculate its surface area to volume ratio.
Surface area = 6 脳 10 脳 10 = 600 nm2 (remember that a cube has six sides)
Volume = 10 脳 10 脳 10 = 1000 nm3
Surface area to volume ratio = \(\frac{\textup{600}}{\textup{1000}}\)
= 0.6
Question
A cube-shaped nanoparticle has sides of 1 nm. Calculate its surface area to volume ratio.
Surface area = 6 脳 1 脳 1 = 6 nm2
Volume = 1 脳 1 脳 1 = 1 nm3
Surface area to volume ratio = \(\frac{\textup{6}}{\textup{1}}\)
= 6