Atomic number
What Atomic number means in Combined Science GCSE, as defined for AQA.
Definitions of Atomic number
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Reference: AQA
Gives the number of protons and hence the number of electrons, so it determines the electron arrangement and the reactivity pattern.
Gives the number of protons and electrons in a neutral atom, and elements are arranged in order of increasing atomic number.
The number of protons, which identifies the element and for a neutral atom also equals the number of electrons.
The number written as a subscript before the element symbol, counting protons and defining the element.
The number of protons only, which is subtracted from the mass number to find the number of neutrons.
The number of protons in the nucleus, which the modern periodic table uses to order elements.
Topics that use Atomic number
- Development of the periodic table (AQA GCSE)
- Mass number, atomic number and isotopes (AQA GCSE)
- Metals and non-metals (AQA GCSE)
- Size and mass of atoms (AQA GCSE)
- The periodic table (AQA GCSE)
Related terms
- Isotopes
- Mass number
- Nuclide notation
- Relative atomic mass
- Atomic structure
- atomic weight
- Chemical reactivity and ion formation
- Covalent bonds
Using Atomic number in the exam
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