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[[NanoparticleNanoparticles]]s are small clumps of [[atom]]s which are between 1 and 100 [[nanometre]]s ([[billion]]ths billionths of a [[metre]]) in [[length]], [[width]] or [[height]].

: A [[Hydrogen]] [[atom]] has a [[radius]] of 0.1[[nanometre]]s so 10 [[Hydrogen]] [[atom]]s lined up can make one [[nanometre]]. A [['''nanoparticle]] ''' may have a [[width]] of as little as 10 [[atom]]s or as many as 1000 [[atom]]s. (NB [[Hydrogen]] is being used as a comparison for the [[width]] and most [[nanoparticlenanoparticles]]s are made of other types of [[atom]].): A [[substance]] that is broken down into [[nanoparticlenanoparticles]]s may have very different [[property|properties]] to large amounts [[Volume (Space)|volumes]] of the [[substance]].: The [[Surface Area to Volume Ratio|surface area to volume ratio]] of [[nanoparticlenanoparticles]]s is much higher than large [[Volume (Space)|volumes]] of the same [[substance]]. It is this large [[Surface Area|surface area]] compared to the [[Volume (Space)|volume]] that gives it the different [[property|properties]].: In 'bulk' [[material]]s a very small proportion of [[atom]]s exist on the surface of the [[material]]. However, for [[nanoparticlenanoparticles]]s a much larger proportion of [[atom]]s exist on the surface allowing those [[particle]]s to interact with others around it. ===Risks of Nanoparticles===: [[Inhale|Inhaling]] [[nanoparticles]] may damage the [[lungs]]. Recent research has suggested Carbon Nanotubes may be [[harmful]] if [[inhale]]d.: [[Nanoparticles]] of certain [[reactivity|reactive]] [[metal]]s [[Chemical Reaction|react]] very quickly with [[Oxygen]] due to their large [[Surface Area]] which could result in an [[explosive|explosion]] if ignited. ===Examples===*[[Zinc Oxide]] - [[Nanoparticles]] of [[Zinc Oxide]] are used in sunscreen to [[absorb (Physics)|absorb]] [[Ultra-violet]] [[light]]. [[Zinc Oxide]] normally forms a white powder, but [[nanoparticles]] of [[Zinc Oxide]] are smaller enough not to for a white layer over the [[skin]].*[[Silver]] - [[Nanoparticles]] of [[Silver]] can prevent the growth of [[Micro-organism]]s.*[[Catalyst]]s - [[Nanoparticles]] of [[Catalyst]]s are far more efficient than larger [[particle]]s due to their very large [[Surface Area|surface area]].*Nanocages - A nanocage made of [[Carbon]] in the form of a fullerene or a Carbon Nanotube can contain a [[drug]] so it can be delivered to the right location in the body.