The development of the model of the atom

This question is about small particles.

Before the discovery of the electron, atoms were thought to be tiny spheres that could not be divided.

The discovery of the electron led to the plum pudding model of the atom.

Describe the plum pudding model of the atom.

The model of the atom changed again after the alpha particle scattering experiment.

Give two conclusions that were made from the alpha particle scattering experiment.

Niels Bohr made another change to the model of the atom.

What was this change?

A helium atom has a radius of 1.4 × 10^–10 m.

The nucleus of this atom has a radius of 1.7 × 10^–15 m.

How many times larger is the radius of the atom than the radius of the nucleus?

Tick () one box.

Nanoparticles contain a few hundred atoms.

Figure 5 represents a cubic nanoparticle.

Calculate the simplest surface area: volume ratio of the cubic nanoparticle.

Lenses in reading glasses often have a scratch-resistant coating that contains a hard substance.

Nanoparticles of the hard substance are used instead of fine particles of the hard substance.

Explain why nanoparticles are used instead of fine particles.

This question is about models of the atom.

Figure 16 shows two early models of the atom.

Name the models of the atom shown in Figure 16.

Compare model A with the model of the atom used today.

Use Figure 16.

Chadwick’s experiments showed the existence of neutrons in an atom.

This led to an understanding of isotopes.

Define the term ‘isotopes’.

Refer to subatomic particles in your answer.

This question is about models of the atom.

Figure 2 shows two early models of the atom.

Name the models of the atom shown in Figure 2.

Compare model A with the model of the atom used today.

Use Figure 2.

Chadwick’s experiments showed the existence of neutrons in an atom.

This led to an understanding of isotopes.

Define the term ‘isotopes’.

Refer to subatomic particles in your answer.

Discoveries in chemistry led to a better understanding of atomic structure.

Atoms were originally thought to be tiny spheres that could not be divided. The plum pudding model of the atom was then developed. Figure 10 represents the plum pudding model of the atom.

Describe the plum pudding model of the atom.

Atoms contain electrons, neutrons and protons. Write these three particles in order of their discovery.

Very few atoms of the element tennessine (Ts) have ever been identified. The atomic number of tennessine is 117

Predict the number of outer shell electrons in an atom of tennessine. Give one reason for your answer. Use the periodic table. Number of outer shell electrons

Tennessine was first identified by a small group of scientists in 2010. Suggest one reason why tennessine was not accepted as a new element by other scientists until 2015.

The discovery of isotopes explained why some relative atomic masses are not whole numbers. Element R has two isotopes. Table 5 shows the mass numbers and percentage abundances of the isotopes of element R.

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

Discoveries in chemistry led to a better understanding of atomic structure.

Atoms were originally thought to be tiny spheres that could not be divided. The plum pudding model of the atom was then developed. Figure 1 represents the plum pudding model of the atom.

Describe the plum pudding model of the atom.

Atoms contain electrons, neutrons and protons. Write these three particles in order of their discovery.

Very few atoms of the element tennessine (Ts) have ever been identified. The atomic number of tennessine is 117

Predict the number of outer shell electrons in an atom of tennessine. Give one reason for your answer. Use the periodic table. Number of outer shell electrons

Tennessine was first identified by a small group of scientists in 2010. Suggest one reason why tennessine was not accepted as a new element by other scientists until 2015.

The discovery of isotopes explained why some relative atomic masses are not whole numbers. Element R has two isotopes. Table 1 shows the mass numbers and percentage abundances of the isotopes of element R.

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

This question is about models of the atom.

Atoms were first thought to be tiny spheres that could not be divided. Which particle was discovered to change this model of the atom? Tick (✓) one box.

Figure 2 shows another model of the atom.

What is the name of this model of the atom?

A scientist fired particles at gold atoms. Some of these particles were scattered. The results led to a different model of the atom. Which type of particle was fired at the gold atoms? Tick (✓) one box.

Which scientist first suggested that electrons orbit the nucleus at specific distances? Tick (✓) one box.

The model of the atom used today has three subatomic particles:

• electrons

• neutrons

• protons.

Complete the sentences.

Atoms of the same element have the same atomic number because they have the

Atoms of the same element can have different mass numbers because they have

Atoms have no overall charge because they have

The radius of a nucleus is approximately 1 × 10^–14 m The radius of an atom is approximately 1 × 10^–10 m A teacher uses a ball of radius 1 cm to represent the nucleus. What could represent the atom on the same scale? Tick (✓) one box.

This question is about the development of scientific theories. Figure 2 shows a timeline of some important steps in the development of the model of the atom.

The plum pudding model did not have a nucleus. Describe three other differences between the nuclear model of the atom and the plum pudding model.

Niels Bohr adapted the nuclear model. Describe the change that Bohr made to the nuclear model.

Mendeleev published his periodic table in 1869. Mendeleev arranged the elements in order of atomic weight. Mendeleev then reversed the order of some pairs of elements. A student suggested Mendeleev’s reason for reversing the order was to arrange the elements in order of atomic number. Explain why the student’s suggestion cannot be correct. Use Figure 2.

Give the correct reason why Mendeleev reversed the order of some pairs of elements.

This question is about atomic structure.

Atoms contain subatomic particles. Table 2 shows properties of two subatomic particles. Complete Table 2.

An element X has two isotopes. The isotopes have different mass numbers.

Define mass number.

Why is the mass number different in the two isotopes?

The model of the atom changed as new evidence was discovered. The plum pudding model suggested that the atom was a ball of positive charge with electrons embedded in it. Evidence from the alpha particle scattering experiment led to a change in the model of the atom from the plum pudding model. Explain how.

This question is about the structure of the atom.

Complete the sentences.

Choose answers from the box.

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

The two types of particle in the centre of the atom are the proton

Niels Bohr suggested particles orbit the centre of the atom. This type of particle

The two types of particle with the same mass are the neutron

Suggest the identity of element X.

Use the periodic table.

The radius of an atom of element X is 1.2 10^-10 m

The radius of the centre of the atom is the radius of the atom.

Calculate the radius of the centre of an atom of element X.

Give your answer in standard form.

Figure 3 represents different models of the atom.

Which diagram shows the plum pudding model of the atom?

Tick one box.

Which diagram shows the model of the atom developed from the alpha particle scattering experiment?

Tick one box.

Which diagram shows the model of the atom resulting from Bohr’s work?

Tick one box.

Define the mass number of an atom.

Element X has two isotopes. Their mass numbers are 69 and 71 The percentage abundance of each isotope is:

Estimate the relative atomic mass of element X. Tick one box.

Chadwick’s experimental work on the atom led to a better understanding of isotopes. Explain how his work led to this understanding.