Alkali metals and Halogens

Name the first 5 elements in Group 1

Lithium, sodium, potassium, rubidium, caesium

Which three elements are unusually soft and more reactive than calcium?

Lithium, sodium and potassium

What happens when sodium is cut open?

Sodium corrodes quickly when exposed to air
The freshly cut surface of sodium is shiny

Why are lithium, sodium and potassium all stored in paraffin oil?

To prevent reaction with oxygen in the air

What are the products of metal and water reacting together?

Metal + water → metal hydroxide solution + hydrogen

What pH are metal hydroxide solutions?

They are STRONGLY ALKALINE

What can we observe when lithium reacts with water?

• Fizzing/effervescence

• Metal floats and moves on the surface

• Metal gets smaller and eventually disappears

What can we observe when sodium reacts with water?

• Fizzing/effervescence

• Metal floats and moves on the surface

• Metal gets smaller and eventually disappears

• It also MELTS into a ball

• And forms a WHITE TRAIL on the surface

What can we observe when potassium reacts with water?

• Fizzing/effervescence

• Metal floats and moves on the surface

• Metal gets smaller and eventually disappears

• It also MELTS into a ball

• And forms a WHITE TRAIL on the surface

• AND it produces a lilac flame

Describe the trend in the reactivity of the metals in group 1

Reactivity increases as you go down Group 1

What is the reactivity series of metals (most reactive to least)

1. Potassium

2. Sodium

3. LIthium

4. Calcium

5. Magnesium

6. Aluminium

7. Zinc

8. Iron

9. Copper

10. Silver

11. Gold

Why is sodium more reactive than lithium?

Outer shell electrons are further away from the nucleus

Weaker force of attraction between the nucleus and the outermost electrons

Lost more easily

Why can a demonstration of caesium with water not be carried out in school?

Caesium is much more reactive than potassium, so it reacts explosively

What are the first 4 elements in Group 7?

Fluorine, chlorine, bromine and iodine

Which halogens are gases at room temperature?

Fluorine and chlorine

Which halogen(s) are liquid at room temp?

Bromine

Which halogen(s) are solid at room temp?

Iodine

Describe the trend of melting and boiling points in the halogens

Melting and boiling points increase down the group

Explain the trend of melting and boiling points in the halogens

Molecules get bigger, contain more electrons

Forces of attraction between molecules gets stronger

More energy is needed to overcome them

Describe what fluorine looks like at room temperature

Pale yellow gas

Describe what chlorine looks like a room temperature

Pale green gas

Describe what bromine looks like a room temperature

Red-brown liquid

Describe what iodine looks like at room temperature

Dark grey solid

Describe what astatine looks like at room temperature

Black solid