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Alkali Metals in Water

Source URL

https://www.youtube.com/watch?v=jI__JY7pqOM

WARNING: This experiment should be conducted under adult supervision. Make sure to wear gloves and glasses and do this experiment in a safe open area.

Materials

  1. Water

  2. Sodium, Potassium, or Rubidium

  3. A large container

  4. Gloves

  5. Glasses

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Procedure:

  1. Fill your bowl or large container three quarters of the way with cold water.

  2. Place the container in a safe area (outside) away from other items and materials

  3. Cut out a small 1cm by 1cm piece from the metal 

  4. Place the metal in water and observe (Make sure to wear gloves and glasses)

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Results:

After a few seconds, the metal will start rapidly vibrating and swirling around the water. Bubbles will form around the element and you might notice a few sparks in the water.

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Science behind this experiment:

Valency

The elements Sodium, Potassium, and Rubidium fall into the category of Alkali Metals, which only have 1 valence electron. All elements want to ultimately get an outer shell of 8 electrons, which results in the atoms of Alkali metals immediately losing their outer electron when placed in water. Since the remaining atom is now highly positively charged, the ions repel each other and within seconds, atoms start shooting out of the metal. This incident is commonly known as the Columbs explosion. Additionally, while the electrons from the metal flow into the water, hydroxide and hydrogen gas is formed. Hydrogen gas is extremely flammable in air, and in the presence of heat it produces flames. This is why more flames are present when this experiment is conducted  in warm water rather than cold water.

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Associated text: 

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