GCSE Combined Science (AQA)

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Atomic Number

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Atomic structure Atoms and isotopes

Atomic Number

2:06 Atomic Structure
Spec 4.4.1.2
Previous Electrons Next Mass Number & Isotopes
  • The atomic number of an atom equals the number of protons in its nucleus.
  • Protons are represented by blue circles with plus signs in diagrams.
  • A nucleus with four protons has an atomic number of four.
  • Neutrons are depicted as plain green circles.
  • Atomic number is crucial for categorizing atoms.
  • Atoms of the same element have the same atomic number.
  • The periodic table arranges elements by atomic number.
  • Atomic number increases as you read down rows and along columns in the periodic table.
  • The periodic table is a reference for atomic properties, not detailed physics use.
  • Atoms of the same element have the same number of electrons as protons.
  • Electrons orbit the nucleus in shells.
  • The atomic number determines an element's chemical properties.
  • Chemical properties involve electron interactions forming chemical bonds.
  • Atomic notation uses the bottom number to represent the atomic number.
  • Elements are written with a letter symbol and numbers to the left, above, and below.
  • The atomic number is the bottom number in atomic notation.
  • The letters indicate the element type.
  • Beryllium is the only element with four protons in its nucleus.

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