The development of the model of the atom

This question is about atoms and ions.

The model of the atom has changed over time.

In an early model, scientists thought the atom was a tiny sphere that could not be divided.

Figure 1 represents this early model of the atom.

The discovery of a subatomic particle led to a change in the model in Figure 1.

Which was the first subatomic particle to be discovered?

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In a later model of the atom, most of the mass was concentrated in the centre of the atom.

What is the name of the centre of an atom?

Atoms contain three types of subatomic particle.

Draw one line from each subatomic particle to the relative charge of the particle.

What is meant by the ‘atomic number of an atom’?

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Table 1 shows information about two isotopes of an element.

Calculate the relative atomic mass (A_r) of the element.

Use the equation:

A = (mass number × percentage) of isotope A + (mass number × percentage) of isotope B

Give your answer to 1 decimal place.

An oxygen atom has eight electrons.

Complete Figure 2 to show the electronic structure of an oxygen atom.

Figure 2

Figure 3 represents two models of sodium chloride.

What are two advantages of model B compared with model A ?

Tick () two boxes.

This question is about atoms, ions and elements.

Figure 3 shows the results of the alpha particle scattering experiment.

In the experiment, alpha particles were fired at gold foil.

Alpha particles are positively charged.

What two conclusions were made from the results?

Tick () two boxes.

Particle X consists of:

• 35 protons

• 44 neutrons

• 36 electrons.

Why is particle X not an atom?

Answer in terms of subatomic particles.

Which is the correct representation of particle X ?

Use the periodic table.

Tick () one box.

Group 7 elements are known as the halogens.

Table 2 shows the boiling points of some Group 7 elements.

Explain the increase in the boiling points of the Group 7 elements going down the group.

Chlorine reacts with fluorine to form a compound with the formula ClF₃

What is the type of bonding in the compound ClF₃?

Chlorine reacts with a solution of sodium bromide.

Complete the word equation for the reaction.

Explain why Group 7 elements become less reactive going down the group.

All substances are made from atoms.

Figure 1 represents a beryllium atom.

What is the number of protons and the number of neutrons in the beryllium atom?

Figure 2 represents a beryllium ion.

What is the relative charge on a beryllium ion? Tick (✓) one box.

Figure 3 shows the arrangement of atoms in the three states of matter.

What state of matter is represented by state C in Figure 3 ? Tick (✓) one box.

What is the name of the process when state B changes into state A ?

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How can state B be changed into state C ?

Experimental evidence led to the scientific model of the atom changing over time.

Figure 4 shows three models for the atom.

Tick (✓) one box.

Complete the sentence. Choose the answer from the box.

The existence of neutrons was discovered by

Group 7 elements are known as the halogens. All atoms of Group 7 elements contain protons, neutrons and electrons.

What is the order of discovery of the proton, neutron and electron? Tick (✓) one box.

Table 1 shows the mass of a proton and of an electron.

Calculate how many times heavier a proton is than an electron.

A bromine atom can be represented as⁸¹₃₅Br.

What is the number of neutrons in this bromine atom?

What is the number of electrons in a bromide ion ?

Chlorine has two isotopes. Table 2 shows the percentage abundance of the two isotopes of chlorine.

Calculate the relative atomic mass (A_r) of chlorine.

Figure 4 shows the outer shells in one molecule of chlorine (Cl₂). Complete the dot and cross diagram to show the electrons in the outer shells.

This question is about the periodic table.

Figure 11 shows part of Mendeleev’s version of the periodic table.

Which group of elements had not been discovered when Mendeleev’s version of the periodic table was published?

Figure 12 represents different models of the atom.

Which model represents the plum pudding model? Tick (✓) one box.

Which model resulted from Chadwick’s experimental work? Tick (✓) one box.

Potassium has different isotopes.

What is meant by ‘isotopes’? You should refer to subatomic particles.

Table 2 shows the mass numbers and the percentage abundance of two isotopes of potassium.

Calculate the relative atomic mass (A_r) of potassium. Give your answer to 1 decimal place.

This question is about the periodic table.

Figure 1 shows part of Mendeleev’s version of the periodic table.

Which group of elements had not been discovered when Mendeleev’s version of the periodic table was published?

Figure 2 represents different models of the atom.

Which model represents the plum pudding model? Tick (✓) one box.

Which model resulted from Chadwick’s experimental work? Tick (✓) one box.

Potassium has different isotopes.

What is meant by ‘isotopes’? You should refer to subatomic particles.

Table 1 shows the mass numbers and the percentage abundance of two isotopes of potassium.

Calculate the relative atomic mass (A_r) of potassium. Give your answer to 1 decimal place.

This question is about gold and compounds of gold. In the alpha particle scattering experiment alpha particles are fired at gold foil. Alpha particles are positively charged. Figure 4 shows the results.

Some alpha particles are deflected. Complete the sentence. Choose the answer from the box.

Some alpha particles are deflected because the nucleus of the atom is.

Why are most alpha particles not deflected? Tick (✓) one box.

What was one conclusion from the alpha particle scattering experiment? Tick (✓) one box.

Gold reacts with the elements in Group 7 of the periodic table.

What are Group 7 elements known as? Tick (✓) one box.

Fluorine, chlorine and bromine react with gold. Which element will be the most reactive with gold?

Tick (✓) one box.

3.94 g of gold reacts with chlorine to produce 6.07 g of gold chloride. The word equation for the reaction is: gold + chlorine → gold chloride Calculate the mass of chlorine that reacts with 3.94 g of gold.

Calculate the relative formula mass (M_r) of gold chloride (AuCl₃). Relative atomic masses (A_r): Cl = 35.5 Au = 197

This question is about gold and compounds of gold.

In the alpha particle scattering experiment alpha particles are fired at gold foil. Alpha particles are positively charged. Figure 5 shows the results.

What two conclusions can be made from the results? Tick (✓) two boxes.

The gold foil is:

• 4.00 × 10^–7 metres thick

• 2400 atoms thick.

What is the diameter of one gold atom in metres? Give your answer to 3 significant figures.

Gold reacts with the elements in Group 7 of the periodic table. 0.175 g of gold reacts with chlorine. The equation for the reaction is:

Calculate the mass of chlorine needed to react with 0.175 g of gold. Give your answer in mg Relative atomic masses (A_r): Cl = 35.5 Au = 197