Alkali Metals: Properties, Reactivity, and Trends in the Periodic Table

This lesson covers alkali metals in group one of the periodic table, focusing on their properties and reactivity trends. It includes practical demonstrations with lithium, sodium, and potassium, showing their reactions with water. The lesson highlights the increasing softness and reactivity of alkali metals down the group, as well as changes in density, melting, and boiling points.

Which of the following elements is not an alkali metal?

• Lithium

• Sodium

• Calcium

• Potassium

What is the charge of the ion formed when an alkali metal loses its valence electron?

• -1

• +1

• +2

• 0

What happens when lithium is added to water?

• It floats, fizzes, and slowly disappears.

• It sinks and remains unreactive.

• It changes color to red.

• It explodes immediately.

What color does the universal indicator turn when lithium reacts with water?

• Yellow

• Blue or Purple

• Green

• Red

How does sodium's reaction with water compare to lithium's?

• Sodium reacts less vigorously.

• Sodium reacts the same as lithium.

• Sodium does not react at all.

• Sodium reacts more vigorously.

What is a notable observation when potassium reacts with water?

• It does not produce any flame.

• It produces a green flame.

• It sinks to the bottom.

• It burns with a lilac flame.

What sound might you hear when potassium reacts with water?

• A loud bang

• A continuous hissing sound

• No sound at all

• A small popping noise

As you move down the group of alkali metals, what happens to their density?

• It remains the same.

• It decreases.

• It increases.

• It fluctuates randomly.

What trend is observed in the melting points of alkali metals as you move down the group?

• Melting points fluctuate.

• Melting points remain constant.

• Melting points decrease.

• Melting points increase.

Which alkali metal is known to be radioactive and rare in nature?

• Lithium

• Sodium

• Francium

• Cesium