Group 1 and Water

Why are alkali metals stored under oil?

• To make them more visible
• To prevent reaction with oxygen and water vapour in the air.

• To increase their reactivity
• To enhance their conductivity

Why did sodium and potassium melt during the reaction with water?

• The heat generated during the reaction is higher than the metals melting point.

• The reaction released a freezing agent that melted the metals.
• The water was too cold, causing the metals to melt.
• Sodium and potassium have a low melting point naturally.

What gas was released in the reaction between alkali metal and water?

• Oxygen gas
• Nitrogen gas
• Hydrogen gas
• Carbon dioxide gas

What observations are seen between lithium and water?

• Lithium reacts with water to form lithium chloride and hydrogen gas.
• Lithium fizzed producing hydrogen gas and floated on the surface of the water.

• Lithium reacts with water to form lithium oxide and hydrogen gas.
• Lithium reacts with water to form lithium carbonate and hydrogen gas.

What observations are seen between sodium and water?

• Sodium fizzes in water producing hydrogen gas, it floats and melts into a ball.

• Sodium dissolves in water without any reaction.
• Sodium and water create a colorless gas.
• Sodium forms a solid precipitate when mixed with water.

What observations are seen between potassium and water?

• Potassium fizzes in water, it floats and bursts into a lilac flame.

• Potassium reacts with water to produce nitrogen gas and potassium carbonate.
• Potassium reacts with water to produce carbon dioxide and potassium sulfate.
• Potassium reacts with water to produce oxygen gas and potassium chloride.

What observations show that alkali metals are soft metals?

• Alkali metals are brittle and cannot be easily shaped.
• Alkali metals are hard metals due to their high density.
• Alkali metals have high melting points and cannot be cut with a knife.
• Alkali metals can be easily cut with a knife.

Why do alkali metals tarnish quickly after cutting?

• Alkali metals react with carbon dioxide in the air to form carbonates on their surface.
• Alkali metals react with sulfur in the air to form sulfides on their surface.
• Alkali metals react with nitrogen in the air to form nitrides on their surface.
• Alkali metals react with oxygen in the air to form oxides and on their surface.

Order the group 1 metals from least reactive to most reactive.

• Caesium

• Lithium

• Sodium

• Rubidium

• Potassium

What are two observations that show the increase in reactivity down group 1?

• Reaction got faster and potassium burst into a lilac flame

• Increase in atomic radius and increase in ionization energy
• Decrease in atomic radius and decrease in ionization energy
• Decrease in atomic radius and increase in ionization energy