Introduction to the atom | Chemistry of life | Biology | Khan Academy | Summary and Q&A

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August 25, 2009
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Introduction to the atom | Chemistry of life | Biology | Khan Academy

TL;DR

Atoms, the fundamental building blocks of matter, are philosophically intriguing due to their abstract nature and the concept of electron orbitals.

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Questions & Answers

Q: How were atoms originally conceptualized by philosophers?

Philosophers theorized that atoms were the smallest, indivisible units of matter, based on the idea of cutting an apple into smaller and smaller pieces until reaching an uncuttable piece.

Q: How are electron orbits different from the orbits of planets?

Electron orbits are not like planetary orbits. Electrons exhibit wave-like behavior and have a probability distribution of being located in different places, rather than following a fixed path.

Q: What determines the identity of an element?

The number of protons in an atom's nucleus determines the element's identity. This number is referred to as the atomic number.

Q: Why are atoms mostly empty space?

Most of an atom's volume is composed of empty space because electrons occupy a vast region around the nucleus, and most of the atom's mass is concentrated in the nucleus.

Summary & Key Takeaways

  • Atoms were originally thought to be indivisible and were referred to as "uncuttable." However, we now know that atoms are composed of smaller particles such as protons, neutrons, and electrons.

  • Early models of the atom depicted electrons orbiting around a nucleus, but this has been proven inaccurate. Electron behavior is described by probability functions known as orbitals.

  • The number of protons determines an element's identity, while the number of neutrons and electrons can vary.

  • Atoms are mostly empty space, with the nucleus accounting for a tiny fraction of the atom's volume.

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