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Inside the Atom Flashcards

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Describe the structure of an atom.

A small, positively charged nucleus containing protons and neutrons, surrounded by negatively charged electrons orbiting at set distances.

What is the typical size (order of magnitude) of an atom?

About 1×10−10 m1\times10^{-10}\ \mathrm{m} (0.1 nm) across. Small molecules are of a similar order, up to about 10−9 m10^{-9}\ \mathrm{m}.

Where is almost all of the mass of an atom found?

In the nucleus.

How does the radius of the nucleus compare with the radius of the whole atom?

The nucleus is at least 10 000 times smaller — about 10−14 m10^{-14}\ \mathrm{m} compared with 10−10 m10^{-10}\ \mathrm{m}.

True or false? Most of an atom is empty space.

True. The nucleus and electrons occupy a tiny fraction of the atom's volume.

What are the steps to estimate how many atoms fit across a thin foil?
e.g. foil 4.0×10−7 m4.0\times10^{-7}\ \mathrm{m} thick, atom diameter 0.15 nm0.15\ \mathrm{nm}

  1. Put the atom diameter in metres: 0.15 nm=1.5×10−10 m0.15\ \mathrm{nm}=1.5\times10^{-10}\ \mathrm{m}
  2. Divide thickness by atom diameter: 4.0×10−71.5×10−10\dfrac{4.0\times10^{-7}}{1.5\times10^{-10}}
  3. Number of atoms ≈2700\approx 2700