Reacting Elements

reaction between sodium metal with water

When the Group 1 Elements react with water they give off hydrogen gas. The heat generated by the chemical reaction sets the hydrogen gas alight and it burns with a coloured flame. Sodium burns with an orange flame.

A powerful chemical reaction is going on here:

Sodium + Water => Hydrogen + Sodium hydroxide

What has happened is that the sodium atom has managed to lose its single electron in the outside shell of its eleven electrons. The energy released has given the reaction enough heat to ignite the hydrogen and cause the sodium metal to skate around the surface of the water.

Potassium is also a metal that is found in Group 1 of the periodic table. However, potassium has more electrons than sodium and is more reactive than the other metal.

You can see that the potassium reaction with water also produces a flame: in this case a lilac-coloured one. The flame in this photograph doesn't look as big - this is because the reaction finished much more quickly ... and also because I didn't want to put too much of this dangerous metal into the water!

The chemical reaction in this case is:

Potassium + Water => Hydrogen + Potassium hydroxide

... again, the gas produced is hydrogen - which soon sets alight.

reaction between potassium metal with water


Fill in these missing words ...

Sodium and potassium are found in group of the table. They are both metals and react with water to produce gas. The heat given off by the reaction will set the hydrogen alight.

Sodium burns with an flame whereas potassium burns with a coloured one.

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Now answer these questions:

  1. How many electrons are in the outer shell of sodium and potassium ?
  2. In which group of the periodic table do you find sodium and potassium ?
  3. Which is the most reactive element in the list ?
  4. What gas is produced when sodium reacts with water ?
  5. What else is produced when sodium reacts with water ?
  6. What colour flame does sodium produce ?
  7. What colour flame does potassium produce ?
  8. What is the chemical symbol for potassium ?
  9. What is the chemical symbol for sodium ?
  10. What is the chemical formula for sodium hydroxide ?

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When potassium reacts with water it is the electrons of the atoms involved that are causing the chemical reaction to take place.

Potassium wants to get rid of an electron; water (H2O) splits into an H and an OH ... the OH really wants an electron. The left over H joins up with another H to form a gas: hydrogen.

When potassium loses an electron it is called a positive ion

When the OH gains an electron it forms a negative ion

The potassium and OH ions join together to form a new molecule: potassium hydroxide. The metals in group one react in this strong way: by losing electrons and forming positive ions. This means that many of the reactions carried out by group one metals are called ionic reactions.

electrons orbit the nucleus

Now fill in these missing words ...

It is the that are involved in the chemical reaction between potassium and water. The potassium atom really wants to get rid of electron and the OH group really wants to collect one more .

The electron leaves the hydrogen - turning it into a positive . The chemical reaction between potassium and water to make potassium hydroxide is called an reaction.

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