1.1. This question is about hydrogen, the element with atomic number Z = 1.

i) Hydrogen has two stable isotopes. Complete the table to show the number of subatomic particles present in the nuclei of these two isotopes of hydrogen.

(1)

ii) Use the data in the table to explain the term isotopes.

(2)

1.2. The relative atomic mass of hydrogen in the Periodic Table is 1.0.

This is correct to two significant figures.

The table gives data for the relative isotopic mass and natural abundance of the two stable isotopes of hydrogen.

i) Using the data in the table, give a reason why it can be estimated that the relative atomic mass of hydrogen is greater than 1.0. 

(1)

 ii) Calculate the relative atomic mass of hydrogen from these data, giving your answer to four decimal places. 

(2)

1.3. i) Write an equation to represent the first ionisation energy of hydrogen.

Include state symbols.

 (2)

ii) The sequence of the first three elements in the Periodic Table is hydrogen, helium and then lithium. 

Explain why the first ionisation energy of hydrogen is less than that of helium, but greater than that of lithium.

 (4)

1.4. Hydrogen can be placed in several different positions in periodic tables. One is immediately above lithium in Group 1. Another is in the centre of the first row, as shown in the Periodic Table on the back cover.

Criticise the position of hydrogen immediately above lithium by giving one reason in favour and two against.