Alkali metals are a group that you can find in Group 1 of the periodic table. They have some really interesting changes as you go from lithium (Li) to cesium (Cs). Let’s take a closer look at how their properties change:

1. Reactivity

• More Reactive Down the Group: Lithium is pretty stable, but when we get to sodium (Na) and potassium (K), they become much more reactive. By the time we reach cesium (Cs), these metals can explode when they touch water!

2. Melting and Boiling Points

• Lower Melting and Boiling Points: Lithium melts at 180.5 °C, but cesium only melts at 28.5 °C. This shows that larger alkali metals have weaker bonds holding them together.

3. Density

• Heavier Down the Group: Lithium is the lightest, while cesium is much denser. This happens because the atoms get bigger and heavier as you move down the group.

4. Color and Appearance

• Shiny but Changes Over Time: Alkali metals are shiny but lose that shine quickly when they are in the air. Sodium looks bright silver, but potassium changes color quickly because of oxidation.

In summary, as you go down the alkali metal group, they become more reactive, have lower melting points, greater density, and their appearance changes over time. It’s a fascinating journey through the periodic table!