2.3 Alkali Metals

Question 1

What group of the periodic table are alkali metals in?

Answer 1

Group 1

Question 2

How do melting and boiling points behaving going down the group?

Answer 2

Decrease

Question 3

What happens when alkali metals react with water?

Answer 3

Alkali metals all react with water to produce hydrogen and an alkaline solution containing the metal hydroxyde. Ex. Sodium 2NA 9s) + 2H2O(l) = Sodium Hydroxyde 2NaOH (aq) + hydrogen H2 (g)
Litium, sodium or potassium float and fizz when added to water. Potassium reacts so vigourously that it burns with a lilac flame. The solution is colourless with a high Ph. Universal indicator turns purple

Question 4

What are the properties of alkali metals?

Answer 4

• very reactive (need storing in oil to avoid reacting with oxygen in the air); reactivity increases going down the group. This is because they only have 1 electron in the outermost shell. They react with non metals loosing their electron and forming positive ions
• low density compared to other metals
• Soft and can be cut with a knife

Question 5

How do alkali metals react with chlorine, fluorine, bromine and iodine?

Answer 5

• they produce metal chlorides which are solids and dissolve in water to form colourless solutions
• Reactions become more vigouros going down the group
• Ex sodium 2NA (s) + chlorine Cl2 (g) = 2NaCl (s)