Chemistry chapter 1 Revision questions Very helpful PDF

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1 Atomic structure Exam-style questions

AQA Chemistry

1 From AQA Chemistry Unit 1 Foundation Chemistry CHEM1 May 2014 (Question 1). a Table 1.1 shows some data about fundamental particles in an atom. Table 1.1 Mass of fundamental particles Particle

proton

neutron

electron

Mass / g

1.6725 × 10–24

1.6725 × 10–24

0.0009 × 10–24

i

An atom of hydrogen can be represented as 1H. Use data from Table 1.1 to calculate the mass of this hydrogen atom.

1.6734x10-27 kg ii

(1 mark)

Which one of the following is a fundamental particle that would not be deflected by an electric field? A electron B neutron C proton Write the correct letter, A, B, or C, on the line below.

B

(1 mark)

b A naturally occurring sample of the element boron has a relaive atomic mass of 10.8. In this sample, boron exists as two isotopes, 10B and 11B. i Calculate the percentage abundance of 10B in this naturally occurring sample of boron. 10.8 = (10) (x) + (11) (1-x) 10.8 = 10x + 11 – 11x 10.8 – 11 = 10x-11x -0.2 = -x X = 0.2

0.2x100 = 20%

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(2 marks)

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1 Atomic structure Exam-style questions

AQA Chemistry ii

State, in terms of fundamental particles, why the isotopes 10B and 11B have similar chemical reactions. They have the same electronic configuration

(1 mark) c Complete Table 1.2 by suggesting a value for the third ionisation energy of boron. Table 1.2 Ionisation energies of boron.

Ionisation energy / kJ mol–1

First

Second

Third

Fourth

Fifth

799

2420

7500

25 000

32 800

d Write an equation to show the process that occurs when the second ionisation energy of boron is measured. Include state symbols in your equation. B+ (g)  B2+ (g) + 2ee

(1 mark)

Explain why the second ionisation energy of boron is higher than the first ionisation energy of boron. Electron is being removed from a positive ion therefore, needs more energy. (1 mark)

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2

1 Atomic structure Exam-style questions

AQA Chemistry

2 From AQA Chemistry Unit 1 Foundation Chemistry CHEM1 January 2012 (Question 7) The mass spectrum of a sample of krypton taken from a meteorite is shown in Figure 2.1.

Figure 2.1 Mass spectrum of a sample of krypton Use this spectrum to calculate the relative atomic mass of this sample of krypton. Give your answer to one decimal place. Explain why the value you have calculated is slightly different from the relative atomic mass given in the Periodic Table. (82x2) + (83x2) + (84x10) + (86x3) = 1428 1428/17 = 84.0 Periodic table takes account of other sample of krypton

(4 marks)

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1 Atomic structure Exam-style questions

AQA Chemistry

3 From AQA Chemistry Unit 1 Foundation Chemistry CHEM1 January 2013 (Question 1) a State the meaning of the term mass number of an isotope. Total number of protons and neutrons in the nucleus of an atom (1 mark) b Give the symbol of the element that has an isotope with a mass number of 68 and has 38 neutrons in its nucleus. Zn

(1 mark)

c A sample of element R contains isotopes with mass numbers of 206, 207 and 208 in a 1:1:2 ratio of abundance. i Calculate the relative atomic mass of R. Give your answer to one decimal place. (206x1) + (207x1) + (208x2) = 829 829/4 = 207.3

(3 marks) ii

Identify R. Lead

iii

(1 mark)

All the isotopes of R react in the same way with concentrated nitric acid. State why isotopes of an element have the same chemical properties. They have the same chemical property because there electron configuration is the same (1 mark)

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1 Atomic structure Exam-style questions

AQA Chemistry

4 From AQA Chemistry Unit 1 Foundation Chemistry CHEM1 January 2011 (Question 2) Indium is in Group 3 in the Periodic Table and exists as a mixture of the isotopes 113 In and 115In. a Use your understanding of the Periodic Table to complete the electron configuration of indium. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d105p1

(1 mark)

b A mass spectrum of a sample of indium showed two peaks at m/z  113 and m/z  115. The relative atomic mass of this sample of indium is 114.5. i Give the meaning of the term relative atomic mass. Average mass of naturally occurring of isotope of an element relative to 1/12 the relative atomic mass of an atom of carbon 12.

(2 marks) ii Use these data to calculate the ratio of the relative abundances of the two isotopes. 114.5 = (113) (x) + (115) (1-x) 114.5 = 113x + 115 – 115x 114.5 -115 = 113x-115x -0.5 = -2x x=0.25 1:3 (2 marks) c State and explain the difference, if any, between the chemical properties of the isotopes 113In and 115In. Difference in chemical properties None Explanation

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1 Atomic structure Exam-style questions

AQA Chemistry

As they got the same number of electrons and got the same number of electron configuration (2 marks)

d

Phosphorus is also in Period 3 of the Periodic Table. The electron configuration of phosphorus shown in Figure 4.1 is incorrect.

Figure 4.1 Incorrect electron configuration of phosphorus

i

Explain why the arrangement is incorrect They should have 15 electrons. In 3p orbital they should be arranged in parallel spins.

(2 marks)

ii Complete the boxes to show the correct arrangement of phosphorus. (1 mark)

Figure 4.2 Incomplete electron configuration of phosphorus

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1 Atomic structure Exam-style questions

AQA Chemistry

5 a

This question is about the isotopes of neon. Isotopes of neon include 22Ne and 20Ne. Deduce the number of protons in 22Ne.

i

10

ii

(1 mark)

Deduce the number neutrons in 22Ne. 12

(1 mark)

b State and explain the difference, if any, between the chemical properties of the isotopes 22Ne and 20Ne. They have none because as they got the same number of electrons (1 mark)

c

Table 5.1 gives the relative abundance of each isotope in the mass spectrum of neon. Use the data in Table 5.1 to calculate a value for the relative atomic mass of this sample of neon. Give your answer to one decimal place.

Table 5.1 Mass of fundamental particles m/z Relative abundance / %

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20

21

22

90.9

0.26

8.8

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1 Atomic structure Exam-style questions

AQA Chemistry

(2 marks) d Give the full electron arrangement for the isotope 22Ne and suggest why it is unreactive. 1s22s22p6 Neon is unreactive because it has full outer shell (2 marks)

6 A sample of magnesium consists of three isotopes and has a relative atomic mass of 23.32. Table 6.1 shows the relative abundance of two of these isotopes. Table 6.1 Relative abundances of two isotopes of magnesium Mass number of isotope

23

24

Relative abundance / %

79.0

10.0

Use this information to determine the relative abundance and the mass of the third isotope. Give your answer to the appropriate number of significant figures.

100-89 = 11% (23x79) + (24x10) + (X x11) = 23.32 1817+240+11x/100 = 23.32 2057+11x = 2332 11x = 275 X = 25

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8

1 Atomic structure Exam-style questions

AQA Chemistry

(4 marks)

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