Two atoms of sulfur are represented in Fig. 4.1. Fig. 4.1 (a) State what the top number (32 or 34) in the nuclide notation represents. [1] (b) State what th...
Question 1 Report
Two atoms of sulfur are represented in Fig. 4.1.
Fig. 4.1
(a) State what the top number (32 or 34) in the nuclide notation represents. [1]
(b) State what the bottom number (16) in the nuclide notation represents. [1]
(c) State the number of protons, neutrons and electrons in atom Y. [3]
(d) State what is meant by isotopes. [2]
(e) Explain, in terms of electrons, why atom X and atom Y react in the same way. [2]
Answer Details
This question tests nuclide (isotope) notation and why isotopes are chemically identical. In the symbol the top number is the mass number and the bottom number is the proton number.
(a) The top number (32 or 34) is the mass number: the total number of protons and neutrons in the nucleus [1].
(b) The bottom number (16) is the proton number (atomic number): the number of protons in the nucleus [1]. It is the same for both atoms because both are sulfur.
(c) For atom Y (mass number 34, proton number 16): protons = 16 [1]; neutrons = 34 - 16 = 18 [1]; electrons = 16 (equal to protons in a neutral atom) [1].
(d) Isotopes are atoms of the same element (same number of protons) [1] with a different number of neutrons [1]. Atoms X and Y are both sulfur (16 protons) but have 16 and 18 neutrons.
(e) Atom X and atom Y react the same way because they have the same number of electrons and the same electron arrangement (2,8,6) [1], and chemical reactions depend on the (outer) electrons [1]. The extra neutrons in Y change the mass but not the chemistry.
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