EasyChemistryHigh School (11–12)Structure of the Atom › Isotopes and Isobars Structure of the Atom › Subatomic Particles and Atomic ModelsNumericalBoard Exam

Find the numbers of protons, neutrons and electrons in ³²₁₆S²⁻, ²⁴₁₂Mg²⁺ and ¹⁹₉F⁻…

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Find the numbers of protons, neutrons and electrons in ${}^{32}_{16}\text{S}^{2-}$ , ${}^{24}_{12}\text{Mg}^{2+}$ and ${}^{19}_{9}\text{F}^-$ . Which two have the same number of electrons?

Need a reminder? The key ideaShow

$Z$ counts protons, $A$ protons plus neutrons, and $N = A - Z$ . Isotopes share $Z$ , isobars share $A$ , isotones share $N$ . Average atomic mass $=$ the sum of (mass $\times$ share). In a mass spectrometer, $r = \dfrac{1}{B}\sqrt{\dfrac{2mV}{q}}$ , so $r \propto \sqrt{m}$ .

The worked solution

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