Chemistry Data Trends and Graphs

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: