Atomic Structure (Edexcel IGCSE Chemistry): Exam Questions

The diagram below shows two different atoms of hydrogen.

Which particle is missing from one of the diagrams?

The table shows information about the two isotopes of boron.

The relative atomic mass of this sample of boron is:

The diagram shows an atom of an element.

i) What is the name of the particle labelled Y?

(1)

ii) Give the mass number of this atom.

(1)

iii) Name this element. Use the Periodic Table to help you.

(1)

There are two isotopes of this element.

Give one way, in terms of sub-atomic particles, that these isotopes are the same and one way that they are different.

same ..........................................................................................................

..........................................................................................................

different ....................................................................................................................................................................................................................

Thallium, Tl, is an element in Group 3 and Period 6 of the Periodic Table.

The atomic number of thallium is 81

How many electrons are there in the outer shell of an atom of thallium?

A thallium ion has a charge of 3+ 

How many electrons are there in this thallium ion?

A sample of thallium contains two isotopes.

The table shows the mass number and percentage abundance of each isotope in the sample.

 i) Give the number of protons and the number of neutrons in one atom of the thallium-205 isotope.

 (2)

 number of protons: ......................................................................

 number of neutrons:  ...................................................................

 ii) Calculate the relative atomic mass of this sample of thallium.

 Give your answer to one decimal place.

 (3)

Table 1 gives some information about three subatomic particles.

 i) Complete Table 1 by giving the missing information.

 (3)

 Table 1

ii) Give the name of the part of the atom containing protons and neutrons.

(1)

Table 2 shows the numbers of protons, neutrons and electrons in the species U, V, W, X, Y and Z.

 Table 2

 Use the information in Table 2 to answer these questions.

 Each species may be used once, more than once or not at all.

 i) Give the letter of the species that has six electrons in its outer shell.

 (1)

 ii) Give the mass number of Z.

 (1)

 iii) Give the letter of the species that is a positive ion.

 (1)

 iv) Give the letters of the two species that are isotopes of the same element.

 (1)

A sample of neon contains two isotopes, ²⁰Ne and ²²Ne 

The relative abundances of the two isotopes in the sample are 

²⁰Ne 91.2%    ²²Ne 8.80%

 Calculate the relative atomic mass of this sample of neon. 

Give your answer to one decimal place.

relative atomic mass = ..............................

The diagram shows the electronic configuration of an atom of an element.

Complete the table by giving the missing information about this atom.

This element has three isotopes. The table shows the mass number and percentage abundance of each isotope in a sample of this element.

Calculate the relative atomic mass (A_r) of this element. Give your answer to one decimal place.

Complete the table to show the relative mass and relative charge of a proton and a neutron. 

Magnesium has three isotopes.

i) State the meaning of the term isotopes.

(2)

ii) The symbol for an atom of one isotope of magnesium is

 Give the number of protons, neutrons and electrons in one atom of this isotope.

 (2)

 number of protons ..............................

 number of neutrons ..............................

 number of electrons ..............................

 iii) A sample of magnesium contains these percentages of the three isotopes.

 Mg‐24 = 79.00%   Mg‐25 = 10.00%   Mg‐26 = 11.00%

 Use this information to show that the relative atomic mass of magnesium is 24.32

 (2)

 iv) One mole of magnesium has a mass of 24.32 g.

 There are 6.022 × 10²³ atoms in one mole.

 Calculate the mass, in grams, of one atom of magnesium.

 Give your answer to 4 significant figures.

 (2)

mass = .............................................................. g

The equation for the reaction between magnesium and oxygen is 

2Mg + O₂ → 2MgO 

Determine the maximum amount, in moles, of magnesium oxide that can be produced from 0.50 mol of magnesium and 0.20 mol of oxygen.

amount = .............................................................. mol

State the meaning of the term atomic number.

An atom of element X contains 14 protons, 14 electrons and 15 neutrons.

 i) Which of these is the mass number of this atom?

 (1)

 ii) Explain which group of the Periodic Table element X belongs to.

 (2)

The table shows the composition of a sample of a different element, Y, containing three isotopes. 

 Using information from the table, calculate the relative atomic mass (A_r) of this sample of element Y.  

Give your answer to one decimal place.

 A_r = ..............................

The diagram represents an atom of boron.

Use information from the diagram to complete the table. The first row has been done for you.

Boron has two isotopes, boron-10 and boron-11.

A sample of boron contains 18.7% of boron-10 and 81.3% of boron-11.

Calculate the relative atomic mass of this sample of boron.

This question is about atomic structure.

A group of students looks at the diagram below showing the arrangement of electrons in a chemical substance.

The students make the following incorrect or incomplete conclusions:

• Student 1 states that the substance is fluorine, neon or sodium

• Student 2 states that it is not possible to determine which atom or ion the diagram represents

• Student 3 states that the mass number is 10

Explain how students 1 and 2 could combine their ideas to produce one possible correct conclusion with an appropriate justification.

Evaluate student 1's suggestions of fluorine and sodium.

Correct student 3's statement. Explain your reasoning.

The students are told that the diagram represents  . 

Describe the additions that should be made to the diagram to show this.