The Nuclear Atom

Deduce, from the charge on the ion, the number of protons in its nucleus.

Show your working.

number of protons = ______

Write down, in nuclide notation, the symbol for the nucleus of this charged atom.

The isotope in Fig. 5.1 is the only stable isotope of beryllium.

Explain the term ‘isotope’.

Explain what prevents electrons in an atom from escaping.

Complete Fig. 8.1 to show the number of protons and neutrons in one nucleus of each of these isotopes of hydrogen.

Fig. 8.1

Explain, using ideas about electrons, neutrons and protons, why atoms of $^{1}_{1}\text{H}$ and $^{2}_{1}\text{H}$ are uncharged.

Neutral atoms also contain electrons. State which of the four nuclei is surrounded by the greatest number of electrons.

protons,

nucleons,

neutrons.

Describe how the composition of an atom of radon-222 differs from that of an atom of radon-224.

Describe what is observed when the detector is at position J and when it is at position K.

position J ______

position K ______

Explain what these observations show about the structure of a gold atom.

Determine the nucleon number (mass number) of the atom.

______

Explain why the model represents a charged atom.

The student makes a new model of a different isotope of the same element.

Describe the nucleus of this new model.

Determine the number of neutrons in a nucleus of americium-241.

number = ______

Fig. 11.2 shows a model of an atom of the gold foil, with its nucleus at the centre.

The alpha-particle labelled A is deflected by the nucleus, as shown.

On Fig. 11.2, complete the path of the alpha-particle labelled B.

Explain how the alpha-particle scattering experiment provides evidence for the existence of a small nucleus inside the atom.

State one way in which the compositions of the atoms of all lithium isotopes are the same.

State one way in which the composition of a lithium atom of one isotope is different from the composition of a lithium atom of a different isotope.

The nuclide symbols for isotopes of lithium are represented as $^{X}_{Y}\text{Li}$ where $X$ and $Y$ are numbers.

Determine the values of $X$ and $Y$ for the isotope represented by Fig. 8.1.

$X$ = ______

$Y$ = ______

An ion of this isotope of lithium has a single positive charge and is represented as ($^{X}_{Y}\text{Li}^+$).

Describe how the diagram that represents this ion differs from Fig. 8.1.

State which of P, Q, R, S and T is the ionised atom.

State the size and the sign of the charge on the ionised atom.

charge = ______

State which pair from P, Q, R, S and T are isotopes of the same element.

Deduce which atom decays in this way.

Deduce which atom is the product of this decay.

State the name and the number of each type of particle found in one nucleus of $^{235}_{92}\text{U}$.

name of particle ______ number found in nucleus ______
name of particle ______ number found in nucleus ______

State one feature that is the same for the nuclei of all isotopes of uranium.

On Fig. 11.1, mark with a letter P where most flashes occur on the screen.

Describe what is seen on the other parts of the screen.

State two conclusions about atoms of gold that resulted from this experiment.