0.2 The atom  (Page 13/14)

Apparatus:

Method:

1. Dip a clean bamboo stick into the methanol
2. Dip the stick into the salt or powder
3. Wave the stick through the flame from the bunsen burner. DO NOT hold the stick in the flame, but rather wave it back and forth through the flame.
4. Observe what happens

Results:

Conclusion:

The above experiment on flame tests relates to the line emission spectra of the metals. These line emission spectra are a direct result of the arrangement of the electrons in metals.

Energy diagrams and electrons

1. Draw Aufbau diagrams to show the electron configuration of each of the following elements:
   1. magnesium
   2. potassium
   3. sulphur
   4. neon
   5. nitrogen
2. Use the Aufbau diagrams you drew to help you complete the following table:

   Element	No. of energy levels	No. of core electrons	No. of valence electrons	Electron configuration (standard notation)
   $\mathrm{Mg}$
   $\mathrm{K}$
   $\mathrm{S}$
   $\mathrm{Ne}$
   $\mathrm{N}$

3. Rank the elements used above in order of increasing reactivity . Give reasons for the order you give.

Group work : building a model of an atom

Earlier in this chapter, we talked about different 'models' of the atom. In science, one of the uses of models is that they can help us to understand the structure of something that we can't see. In the case of the atom, models help us to build a picture in our heads of what the atom looks like.

Models are often simplified. The small toy cars that you may have played with as a child are models. They give you a good idea of what a real car looks like, but they are much smaller and much simpler. A model cannot always be absolutely accurate and it is important that we realise this so that we don't build up a false idea about something.

In groups of 4-5, you are going to build a model of an atom. Before you start, think about these questions:

• What information do I know about the structure of the atom? (e.g. what parts make it up? how big is it?)
• What materials can I use to represent these parts of the atom as accurately as I can?
• How will I put all these different parts together in my model?

As a group, share your ideas and then plan how you will build your model. Once you have built your model, discuss the following questions:

• Does our model give a good idea of what the atom actually looks like?
• In what ways is our model inaccurate ? For example, we know that electrons move around the atom's nucleus, but in your model, it might not have been possible for you to show this.
• Are there any ways in which our model could be improved?

Now look at what other groups have done. Discuss the same questions for each of the models you see and record your answers.

The following simulation allows you to build an atom
run demo