Group 1 (Alkali Metals) & Group 7 (Halogens)

What happens when sodium reacts with water?

Floats, fizzes, melts into a ball, moves around, produces hydrogen gas and an alkaline solution.

Write the balanced symbol equation for sodium reacting with water.

2Na + 2H₂O → 2NaOH + H₂

How do the reactions of lithium, sodium, and potassium with water show they are a family of elements?

All react vigorously with water, producing hydrogen and an alkaline solution, following the same general equation pattern.

What is the trend in reactivity down Group 1?

Reactivity increases down the group (Li < Na < K).

What evidence shows the trend in reactivity down Group 1?

Potassium reacts more violently and faster with water and air than sodium, which is faster than lithium.

How would rubidium react with water compared to potassium?

More violently and explosively than potassium.

Explain the trend in reactivity down Group 1 in terms of electronic configurations.

The outer electron is in a higher energy shell, further from the nucleus, resulting in weaker attraction and easier loss.

What is the color and physical state of chlorine at room temperature?

Pale green-yellow gas.

What is the color and physical state of bromine at room temperature?

Red-brown liquid.

What is the color and physical state of iodine at room temperature?

Dark grey-black solid.

Describe the trend in physical properties down Group 7.

Darker color, higher melting and boiling points, change from gas to liquid to solid down the group.

What is the predicted color and state of astatine at room temperature?

Dark (black/purple), solid.

Describe a displacement reaction between chlorine and potassium bromide solution.

Chlorine (more reactive) displaces bromine.

Write the symbol equation for the displacement reaction between chlorine and potassium bromide.

Cl₂ + 2KBr → 2KCl + Br₂

Write the ionic equation for the displacement reaction between chlorine and potassium bromide.

Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂

How do displacement reactions show the trend in reactivity in Group 7?

More reactive halogen displaces less reactive one from its compound, showing that reactivity decreases down the group (F > Cl > Br > I).

Explain the trend in reactivity down Group 7 in terms of electronic configurations.

Reactivity decreases down the group; smaller atoms have outer electrons closer to the nucleus, resulting in stronger attraction and easier gain of one electron for a full shell.