C4 - Predicting and Identifying Reactions / Products Flashcards
What is the other name for Group 1 elements?
Alkali metals - they react with water to form an alkali (a metal hydroxide)
List the group 1 metal:
Lithium, Sodium, potassium, rubidium, caesium, francium
What is the physical properties of group 1 metals?
- They are soft - can be cut by knife
- They have low density - lithium, sodium and potassium can float on water
- Low melting and boiling points
Group 1 metals and reactivity:
The reactivity depends on how easily it is to lose an electron.
Reactivity increases as you go down the periodic table:
1) Outermost electron furthest from the positive nucleas. The force of attraction is weaker. Electron easily lost.
2) Electron shielding - there are more electrons in the inner shells as you go down to repel outermost electron.
What happens when alkali metal reacts with cold water:
-They react vigorously
-The reaction produces a hydroxide of the metal and hydrogen gas.
EG:
Sodium + water -> sodium hydroxide + hydrogen gas
-The reactivity increases as you go down periodic table:
Lithium: moves around surface and fizzes furiously
Sodium and potassium: do same but melt from heat of reaction. Potassium - lilac flame can be seen - can ignite the hydrogen gas
Rubidium and Caesium: explode when wet
What happens when alkali metal react with dilute acid?
They produce a salt and hydrogen gas
EG:
Sodium + hydrochloric acid -> sodium chloride + hydrogen
What is the other name for group 7 elements?
Halogen
List the Group 7 elements:
Florine, Chlorine, Bromine, Iodine, Astatine
What do Group 7 metals exist as?
They are diatomic so F2, Cl2, Br2, I2 , At2
How does Chlorine, Bromine, Iodine look like at room temperature?
- > Chlorine: poisonous, green gas
- > Bromine: poisonous, Red-brown liquid giving off orange vapour
- > Iodine: dark grey crystalline solid giving off purple vapour when heated
Halogens and reactivity:
Reactivity depends on how easily it is to gain an electron.
Therefore reactivity decreases as you go down the periodic:
As you go down it gets harder to attract electron as shell is further away from positive nucleus.
What happens when halogens react with alkali metals?
They form salts called ‘metal halides’
EG
Sodium + Chlorine -> Sodium Chloride
What are halogen displacement reaction?
When a more reactive halogen ‘pushes out’ a less reactive halogen in a reaction.
EG
Chlorine + Potassium Bromide -> Potassium chloride + Bromine
1) The Chlorine will displace the Bromine
2) Chlorine is reduced to ions, so salt solution becomes Potassium Chloride.
3) The Bromide ions are oxidised into Bromine, turning solution orange
How do you know in chemical test if halogen has been displaced?
You will see a colour change
What happens when you add Chlorine water (colourless) to:
- Potassium Chloride solution
- Potassium Bromide solution
- Potassium Iodide solution
Potassium Chloride (KCl) -colourless : NO REACTION
Potassium Bromide (KBr) - Colourless: Orange solution (Br2) formed as chlorine displaces Bromine. Bromine ions turn solution orange.
Potassium Iodine (KI) - colourless: Brown solution (I2) formed as chlorine more reactive. The iodine ions make solution Brown.
What happens when you add Bromine water (Orange) to:
- Potassium Chloride solution
- Potassium Bromide solution
- Potassium Iodide solution
Potassium Chloride (KCl) -colourless : NO REACTION
Potassium Bromide (KBr) - Colourless: NO REACTION
Potassium Iodine (KI) - colourless: Brown solution formed (I2) as bromine is more reactive than Iodine. The displaced iodine ions turn solution brown.
What happens when you add Iodide water (Brown) to:
- Potassium Chloride solution
- Potassium Bromide solution
- Potassium Iodide solution
Potassium Chloride (KCl) -colourless : NO REACTION
Potassium Bromide (KBr) - Colourless: NO REACTION
Potassium Iodine (KI) - colourless: NO REACTION
What is the other name for Group 0 elements?
Noble Gases