Isotopes and Relative Atomic Mass

You're viewing free preview questions — 4 questions previewing here — subscribe to unlock 79 more, plus the Full Question Bank, Mock Papers & Worksheets.Upgrade

Isotopes and Relative Atomic Mass — Free MYP5 Chemistry Practice Questions

1QuestionCalculating Relative Atomic Mass RAMConcept Practice

2 marks~3 minCriterion A

A mass spectrum of chlorine shows two peaks: one at

m/z = 35

with a relative abundance of 75.77% and one at

m/z = 37

with a relative abundance of 24.23%.

Deduce the identity of the isotope responsible for each peak, using correct isotopic notation. [1]

Using the data above, calculate the relative atomic mass (RAM) of chlorine. Give your answer to one decimal place. [1]

Solutions

2QuestionCalculating Relative Atomic Mass RAMAssessment Practice

5 marks~8 minCriterion D

A mass spectrometer analyses two iridium samples. The data are:

Sample A:

^{191}

Ir: 37.3% abundance;

^{193}

Ir: 62.7% abundance

Sample B:

^{191}

Ir: 62.7% abundance;

^{193}

Ir: 37.3% abundance

The standard atomic weight of iridium is 192.22.

Use the formula:

A_r = \frac{\sum(m_i \times a_i)}{100}

where

m_i

is the mass number and

a_i

is the percentage abundance.

Calculate

A_r

for both Sample A and Sample B, showing all working. [2]

Compare your calculated values to the standard atomic weight and deduce which sample is from a terrestrial source. [1]

Justify why the other sample is likely to be of meteoritic origin, referring to isotopic composition and nucleosynthetic processes. [2]

Solutions

3QuestionStability of Isotopes and Radioactivity IntroAssessment Practice

8 marks~12 minCriterion C

Four isotopes are listed below.

Isotope	C-12	C-14	U-238	Tc-99m
Protons	6	6	92	43
Neutrons	6	8	146	56
Neutron-to-proton ratio	1.00	1.33	1.59	1.30
Half-life	Stable	5730 years	4.5 billion years	6 hours
Decay mode	None	beta-minus	alpha	gamma

Consider the hypothesis: "All isotopes with more neutrons than protons are unstable."

Identify which isotopes in the table support the hypothesis and which contradict it. Justify your answer using data from the table. [3]

Explain how the band of stability accounts for the stability of C-12 and the instability of C-14. [2]

Evaluate whether the data in the table are sufficient to confirm the hypothesis. In your answer, refer to isotopes not shown in the table. [3]

Solutions

4QuestionDefinition and Examples of IsotopesAssessment Practice

7 marks~11 minCriterion B

The table below shows isotopic data for three elements.

Hydrogen-1	1 proton	0 neutrons	stable
Hydrogen-2	1 proton	1 neutron	stable
Hydrogen-3	1 proton	2 neutrons	radioactive

Carbon-12	6 protons	6 neutrons	stable
Carbon-13	6 protons	7 neutrons	stable
Carbon-14	6 protons	8 neutrons	radioactive

Uranium-235	92 protons	143 neutrons	radioactive
Uranium-238	92 protons	146 neutrons	radioactive

Calculate the neutron-to-proton ratio for each isotope and identify the pattern linking this ratio to nuclear stability. [2]

Deduce a general rule, based on atomic number, that predicts whether an isotope is likely to be stable or radioactive from its neutron-to-proton ratio. [2]

Oxygen-16 has 8 protons and 8 neutrons; oxygen-18 has 8 protons and 10 neutrons. Oxygen-18 is in fact stable. Analyse whether your rule from (b) correctly predicts the stability of each isotope, and evaluate what this reveals about the limitations of a neutron-to-proton ratio rule. [3]

Solutions

Questions 5-83

Unlock these questions with Premium

That's every free question here — 4 of 83.

+79 more questions, plus Mock Papers & Worksheets, are waiting in Premium.

Upgrade