What is an atom?

What is an atom?

1. Nucleus

   • Is held together by the strong force
   • Discovered in 1911 by Ernest Rutherford, physicist from New Zeland

2. Protons

   • Positively charged particles found in the nuclei
   • About 99.86% massive as a neutron
   • Who and when was it discovered?
     • Rutherford discovered them in experiments with cathode-ray tubes that conducted in 1911 and 1919

3. Neutrons

   • How did they discovered
     • Neutrons were found in during experiments when atoms were shot at a thin sheet of berylium
   • have an uncharge particles found in the atom nuclei
   • A neutron's mass is slightly larger than a proton

4. When were atoms created?

   • Atoms were created after the Big Bang in 13.7 billion of years ago
   • When the hot and dense universe cooled up, it became suitable for quarks and electrons to form.
     • Quarks
       • Came together to form protons and neutrons
     • Particles become into a nuclei

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