Lithium Lab Report

Conclusion:

In the experiment, we tested the reactivity of the alkali and alkaline earth metals when they are reacted with water, and when they are reacted with water plus the addition of heat. Each metal had a unique reaction due to several factors including their electronegativity and their atomic radius. We began the lab by experimenting with the alkaline earth metals. The first metal that we chose to react with water was magnesium. When we observed magnesium’s reaction with water, we saw very little take place in the test tube. The magnesium ribbon settled to the bottom of the test tube. When we added the burning splint over the test tube, the reaction wasn’t greatly affected, and a white, cloudy film formed over the test tube. We

We began the alkali metals with lithium, the first in the group. Lithium caused a strong reaction when added to the water. The water bubbled and the reaction made a sizzling noise. The lithium piece at the bottom of the tube spun around until it dissolved. When we added the burning splint, it made a popping noise, but rather than immediately extinguishing, a red flame was briefly lit on the mouth of the test tube. After we added the phenolphthalein, the solution became a light pink color. After testing lithium, we tested sodium. The reaction between sodium and water was similar to the reaction of lithium and water. The sodium spun, caused bubbles, and made a sizzling sound. The flaming splint held over the test tube caused a popping noise and then it extinguished. The addition of phenolphthalein caused the solution to become bright pink. Finally, we tested potassium which caused a large reaction. The potassium instantly began dissolving, and a large amount of gas spilled from the mouth of the test tube. The reaction made a sizzling noise, and the solution left behind was cloudy and white. After adding phenolphthalein to the solution, the solution was left a hot, dark pink color.
Before ending the lab, we observed the addition of phenolphthalein in water compared to the addition of phenolphthalein to sodium hydroxide. When the phenolphthalein was added to water, the water was unchanged.

This is due to the fact that both the ionization energy and electronegativity decrease as you move down a group. These two properties are largely affected by the atomic radius, which becomes larger as you move down a group. A larger atomic radius has more electron shells and therefore more shielding. The shielding of the positive charges from the nucleus makes it highly difficult for the atom to attract electrons, which decreases the electronegativity. The shielding of positive charges also makes it easier for other atoms to remove valence electrons, which lowers the ionization energy. As you across a period, of metals, the reactivity decreases. The reactivity decreases because the atomic radius decreases as well. As the atomic radius increases, ionization energy and electronegativity increase, because the effect of shielding isn't as great as it is on smaller atoms. A larger ionization energy means that the atom is less prone to giving electrons and a larger electronegativity means that the atom has more of an attraction on other atoms'