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Solutions: Atomic Structure

Q11.

(a)

(i) Determine the charge, in C, of a snucleus.

Q = 92 × 1.60 × 10-19 = 1.47 × 10–17 C

(ii) A positive ion with a snucleus has a charge of 4.80 × 10–19 C. Determine how many electrons are in this ion.

number of electrons lost
= magnitude of ion charge/magnitude of charge on an electron = (4.80 × 10–19 )/(1.60 × 10–19 ) = 3
number of electrons remaining on the ion= 92 – 3 = 89

(4)

(b) A s nucleus may decay by emitting two s– particles to form a plutonium snucleus . State what X and Y represent and give the numerical value of each.

X: number of nucleons [or number of neutrons plus protons or mass number]
X = 239
Y: number of protons [or atomic number]
Y = 92 + 2 = 94

(4)
(Total 8 marks)