Chemistry Data Trends and Graphs
Other
Elements in the Periodic Table are organised in rows called „periods‟.
This is because there are regular repeating patterns in physical and chemical properties.
The repeating patterns in properties of elements are due to repeating patterns in their electron configurations. In this activity we look at trends in some of the properties of the elements and how these properties change as we move down and across the periodic table.
Graphs are a useful way of showing trends. In this investigation we will graph melting points, atomic radius and ionisation energy of the first 36 elements (the first 3 periods), and look for trends and patterns.
Use the data provided to construct graphs in the following activity.
Data:
Plot trends in melting point:
Graph atomic number against melting point.
1. What trends in melting point do you observe:
a) Going across a period?
b) Going down a group?
Plot trends in atomic radius:
Graph atomic number against atomic radius.
2.
a) What trend do you observe across a period?
b) What trend do you observe at the start of a period?
c) Explain why the trend in atomic radius moving across a period is different from the trend moving down a group.
Plot trends in ionization energy:
Graph atomic number against ionization energy.
3.
a) What trend do you observe across a period?
b) What trend do you observe at the start of a period?
4.
a) Complete electron shell configuration of Barium below:
Barium: 2, 8, …………………………………. How many electrons are in the outer shell?
b) The first three ionization energies of Barium are shown below:
To remove the outermost electron 1st ionization energy: 502.9 kJ mol-1
To remove the next outermost electron 2nd ionization energy: 965.2 kJ mol-1
To remove the next outermost electron 3rd ionization energy: 3600 kJ mol-1
Explain why the second ionization energy of Barium is relatively small and the third ionization energy is much larger than the first or the second:
5. As we move from left to right across a period, electrons are added one at a time. Explain how this affects the trend in ionization energy shown in your graph:
