It turns out that atoms have an internal structure. While the structure of, say, a gold atom is similar to the structure of a copper atom there are differences so that different types of atom can combine with each other. The rules for how they combine are understood. However, these rules are complex, so far exceeding our ability to predict, with certainty, all the posibilities or the characteristics of combinations. The study of the creation, use, and characteristics of combinations is called chemistry. Almost everything you see, touch, or taste is the result of chemical combinations.

Need example of chemistry in gas, liquid and solid. Maybe a combination. Certainly no text book formulae but something that get the complexities, excitement, and some unknowns across.

Possibly: When rust appears on a metal it is the result of oxygen in the air around you combining with iron.

Other potential topics/thoughts for chemistry are:

• chemistry is the intermediate step between physics and biology
• 
  chemistry is the result of physical proceswses - being able to explain chemistry in terms of physics is one way of demonstrating that our understanding of physics is accurate
• 
  boilogy is the result of chemical processes
• You, and almost everything that affects you, are, at least in part, a result of chemical reactions - the purity of water, the way beer comes about, the drugs you take, even your attraction to a particular girl
• Look up the BZ reaction and just as importantly its history
• Look up carbon buckyballs and its history
• Look up chemical gradients in embryo development
• These will show you the interesting and fun part of chemistry.
  (I'm not internet savvy, so please post links if you find the info on the net)
• (For the down side look up Midgley)

A few outstanding problems in chemistry (or related to) (accuracy not guarenteed)

• prediction of chemical compound properties
• origin of life
• complete description of a burning candle
• molecular computers/storage
• macro/nano size property differences
• water/DNA interaction
• petrolium replacement(s)
• high temperature superconductors
• cloud formation
• gravity versus weightless compound production
• protection from oxygen( rusting)
• simple/cheap/safe drugs
• solar panel efficiency
• water purification

Chemical combinations can be very extensive. The most complex we know of are those that produce life. That is, you, me, worms, trees, fish, and insects. The study of life is called biology. Life comes in cells. Cells are a bit like soap bubbles. They have an outer skin. When the cell is living there is a vast amount of chemical activity going on inside. All this activity is directed at ensuring that the cell continues to do its job. When activity stops the cell dies. Often there is purpose to the dying. For example, your bones and your skin are made of millions and millions of dead cells. When a large number of different types of cells are working together they produce complex life forms such as ourselves. We, and others such as elephants, grass, snails, ant are this exception. Most life comes in small groups of very similar cells; these are called bacteria or sometimes microbes. It is this type of life that first existed on Earth 3.5 billion years ago.

More details on cells e.g. DNA, nuleus, embryo development as the theme(?) Possibly:

When a sperm enters an egg, which is a large cell, a new body starts to be built. This act brings together two strands of DNA. DNA is a long chain of chemicals. Like the words on this page it is the order of these chemicals that is important; they are the instructions that tell the cell what to do. A lot is known about how DNA works but even more remains to be understood. Chemical gradients-differentiation-symmetry.

A cell has previously been described as like a soap bubble with a lot of activity inside. Another anology that has been extensively used else where is that of a dynamic, fast changing, city. Like a city it has fixed roads for transporting traffic (in this case collections of chemicals called proteins), but a cell also destroys and rebuilds roads rapidly. There is a boundary out through which rubbish is sent and in through which, sustanance, energy, and raw material is imported. There are many factories producing items useful to keeping the cell healthy and fulfilling its functions. There is a city council which is even more complex, mysterious, and corruptable than your local government. The major component of the council is DNA. Each creature, human, cow, grass, or fish has its own individual DNA which is applicable to all its different cell types. This is called its genome. Each different type of cell uses a subset of the relevant genome to direct its function and maintenance.

• Which subset? - no one knows
• Interactions within the subset? - not well known
• How can it go wrong? - not well known
• How to repair failures? - not understood
• There is apparently a lot of unused instructions - are they important? Belief in this varies
• How is the subset indentified for a particular type of cell? - no one knows

All types of life exist on the Earth. How they exist, work together, or compete is called ecology.

Ecology is affected by the earth beneath our feet. A lot of what is under our feet used to be alive. Chalk hills used to be small animals floating in the sea. Oil, from which we get petrol, and coal almost certainly started out as trees. It took many millions of years for the change to happen. Sedimentary rocks formed from debris on sea beds, again taking millions of years.

Some concrete examples needed e.g nitrogen-wroms-crops, bird migration, stomach bacteria-digestion.

Medicine