2.18

2.18 How should you explain a trend in a graph at A* level?

State the trend then explain it using nuclear charge shielding distance and electron configuration

2.18 What should you look for in a successive IE graph?

Gradual increases and large jumps indicating changes of electron shell

2.18 What does a graph showing IE against atomic number reveal?

Periodic trends and evidence for shells and subshells

2.18 Why can logarithms of IE be useful on graphs?

They allow very large differences between successive IEs to be displayed clearly

2.18 How can a graph identify an element's group?

Locate the large jump in successive IEs and count electrons removed before it

2.18 How do you distinguish a shell change from a subshell anomaly?

A shell change produces a much larger jump; a subshell anomaly produces a smaller deviation

2.18 What must an A* trend explanation include?

The observed trend plus nuclear charge shielding distance and relevant electron configuration