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The Basics 🤓

  • An alloy is a metal made from the combination of a metallic element and one or more additional elements.
  • This gives them new properties, like being stronger and harder, because the added element(s) distort the structure of the metal and make it more difficult for layers of atoms to slide over each other. 
  • In AP Chemistry, you're expected to know about two types of alloys: substitutional and interstitial.

Source: Chemistry LibreTexts

Substitutional Alloys ⚗️

  • This occurs when the elements are relatively similar in size (note: this means atomic radius and not atomic mass).
  • The added element will replace some of the atoms of the original element in the crystal structure.
  • An example of this is bronze, which is made of copper and tin. 

Interstitial Alloys 📚

  • This occurs when the elements are very different in size.
  • The added element will find its way between atoms of the original element in the crystal structure.
  • An example of this is steel, which is made of iron and carbon. 

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