L01 · 3.1.1.1, 3.1.1.2

Particles and isotopes

Exam conditions

Want proof rather than practice? Try 2 unseen questions alone, one mixed in from an earlier unit, then fix each mark you lose. About 9 minutes.

Start the exam questions The lesson for this unit

4 marksCore chemistry3.1.1.1, 3.1.1.2

An iron ion is written

\mathrm{^{57}_{26}Fe^{3+}}

(a)

State the number of protons in this ion.

[1 mark]

(b)

Calculate the number of neutrons in this ion.

[1 mark]

(c)

Calculate the number of electrons in this ion.

[1 mark]

(d)

Define the term isotopes.

[1 mark]

3 marksCore chemistry3.1.1.1, 3.1.1.2

A sample of gallium contains 60.1% gallium-69 and 39.9% gallium-71.

(a)

Calculate the relative atomic mass of gallium in this sample. Give your answer to 1 decimal place.

[2 marks]

(b)

Explain why gallium-69 and gallium-71 have the same chemical properties.

[1 mark]

3 marksCore chemistry3.1.1.1, 3.1.1.2

Iridium has two isotopes, iridium-191 and iridium-193. A sample of iridium has a relative atomic mass of 192.2.

(a)

Calculate the percentage abundance of iridium-191 in the sample.

[2 marks]

(b)

Deduce the percentage abundance of iridium-193.

[1 mark]

4 marksUnfamiliar context3.1.1.1, 3.1.1.2

Chlorine is 75.0% chlorine-35 and 25.0% chlorine-37. In a mass spectrometer, some

\mathrm{Cl_2}

molecules are ionised without breaking up, giving three molecular ion peaks.

(a)

Give the

m/z

values of the three

\mathrm{Cl_2^+}

peaks.

[1 mark]

(b)

Calculate the percentage of

\mathrm{Cl_2}

molecules that have

m/z = 72

[2 marks]

(c)

Calculate the ratio of the heights of the peaks at

m/z

70 : 72 : 74, in its simplest whole-number form.

[1 mark]

4 marksUnfamiliar context3.1.1.1, 3.1.1.2

Ion X has a charge of 2− and contains 18 electrons and 18 neutrons. Ion Y has a charge of 3+ and contains 21 electrons and 30 neutrons.

(a)

Deduce the element in ion X.

[1 mark]

(b)

Calculate the mass number of X.

[1 mark]

(c)

Deduce the element in ion Y.

[1 mark]

(d)

Calculate the mass number of Y.

[1 mark]