From Hydrogen to Tellurium - POTASSIUM

Potassium


Potassium, with the chemical symbol K, is number 19. Last week we discussed Argon, the inert gas, with its outer electron shell full. This means that Potassium with one extra electron must have three full shells and only one electron in its outer shell. The symbol K comes from the Kalium - the Latin name for this material.


We have talked previously about how elements with the same number of electrons in their outer shells behave similarly chemically and scientists who noticed this started to group the elements according to this. They represented these groups in a now famous diagram known as the periodic table of elements. This week as well as talking about Potassium I am going to introduce you to this famous diagram. Each week we will add our new Element of the Week. It will be shaded in blue and have a red outline.

All the elements we have already discussed are included. Any that are gases at room temperature I have shaded in green. The metals are silver, the solids red and the metalloids purple.


So what about our element of the week, Potassium? Well, it is in the alkali metal group with Sodium and Lithium. Like Sodium, it is very reactive - just mad to give away its outer electron. Lumps of Potassium aren't found in nature because it has long since given away its outer electron to form a compound with some other electron hungry species. Scientists have prepared pieces of Potassium but to keep it you have to store it in oil. It burns in the air giving a purple coloured flame. Check out this video to see what happens
http://www.youtube.com/watch?v=8HdAhs_-Y2g


 It burns in water......check out this video...
http://www.youtube.com/watch?v=veR3gNXs8LQ&NR=1

Potassium containing compounds also give a purple flame when they are burned.

Although it is not found on its own, Potassium is very plentiful on the earth. It exists in many compounds. It is essential for both plant and animal like.
Plants absorb Potassium salts from the earth and if you burn a plant you are left with a substance we call potash - the ash of Potassium!
Farmers add Potassium fertilisers to their fields to help plant growth.


Potassium salts are also dissolved in the sea.


Potassium is essential for human life and each human body is 0.2% Potassium.
To calculate how much Potassium your body contains take your weight in kg and multiply by 0.002. If you weigh 40 kg for example, 80g of that is Potassium! We get Potassium from fruit, nuts and vegetables with potatoes, bananas and dried apricots often being mentioned as good sources.


In our bodies we use Potassium to help our brains work properly, to help our muscles work well and to keep our fluid levels balanced.


People who are concerned about eating too much Sodium in their diets, but like their food to taste salty often use LoSalt. LoSalt is a mixture of Sodium Chloride (table salt) and Potassium Chloride.




Experiment of the Week:
Work out how much potassium your body contains


You will need:
Weighing scales
Calculator or pen and paper


What you do:
Weigh yourself.
Multiply your weight by 0.002


The answer is the amount of your body that is Potassium!