Paper 2: 6+7 Flashcards
What group of the periodic table are the alkali metals?
Group 1
List two properties of alkali metals
Relatively low melting points
Soft
Why are group 1 elements called the alkali metals
They react with water form alkaline solutions
How many electrons are in the outer shell of a group 1 element?
One
Why do elements in the same group have similar chemical properties?
They have the same number of electrons in the outer shell.
What are the products of the reaction between lithium and water?
Lithium hydroxide and hydrogen
Write a balanced symbol equation of the reaction of sodium with water
Why should alkali metals be stored in oil
To prevent them reacting with water vapour and oxygen in the air
What would be observed when lithium reacts with water
Slowest reaction of alkali metals
Bubbles of hydrogen are produced
Doesn’t Melt (highest melting point of alkali metals)
What would be observed when sodium react with water?
Faster reaction than lithium
Floats on the surface of water (less dense than water)
Bubbles of hydrogen are produced which cause the sodium to move on the surface of the water
Melts
What would be observed when potassium reacts with water?
More violent reaction than sodium
Bubbles of hydrogen are produced which cause the potassium to move on the surface of the water
Melts into shiny ball
Burns with a lilac flame
Order of reactivity of first 3 alkali metals
Least: Lithium Sodium Potassium Most:
Why does reactivity increase down group 1
The number of electron shells increases down the group so there is more electron shielding. As a result, there is weaker attraction between the positive nucleus and outer shell electron. This means it is easier to remove an outer shell electron to form a positive metal ion
Which group 1 element would you expect to react most violently with water?
Reactivity increases down the group so francium will react most violently with water.
What group are the halogens in? Why?
Group 7 because they have 7 outer shell electrons.
What is the colour and state of chlorine at room temperature
Pale green gas
What is the colour and state of bromine at room temperature?
Red-brown liquid
What is the colour and state of iodine at room temperature?
Black solid
What state would you expect the halogens fluorine and astatine to be at room temperature?
Fluorine is above chlorine so should have a boiling point lower than chlorine. This means it would be a gas at room temperature.
Astatine is below iodine in group 7 so should have a higher melting point than iodine. Therefore you can predict that it would be a solid at room temperature.
Why does melting and boiling increases down group 7
The molecules get bigger down the group so there are more intermolecular forces to overcome during melting / boiling so more energy is required
What is the chemical test for chlorine
Damp blue litmus paper placed into a test tube of gas. If chlorine is present, the litmus paper will turn red then white due to the bleaching effect of chlorine
Halogens are diatomic. What does this mean?
They form molecules consisting of 2 atoms
E.g: Cl2, Br2 …
What charge does a Halide ion carry? Why?
-1
e.g. Cl-, Br-…
They gain one electron to have a stable
electron configuration
What is produced when a halogen reacts with a metal?
Metal Halide salt
Write a balanced symbol equation between bromine and sodium
Predict the product of the reactor between magnesium and fluorine
Magnesium flouride (MgF2)
Describe the trend in reactivity of the halogens. How does this affect the rate of reaction?
Reactivity decreases down group 7.
Rate of reaction decreases down group 7.
What is formed when hydrogen reacts with a halogen?
Hydrogen halides
e.g. HCl, HBr…
Chlorine reacts with hydrogen in the presence of sunlight but bromine required a flame. Why?
Reactivity decreases down the group so bromine requires more energy for the reaction to occur.
What is formed when a hydrogen halide dissolves in water?
An acidic solution. Hydrogen ions dissociate, making the solution acidic.
Write a balanced symbol equation of the reaction between hydrogen and chlorine
H2 + Cl2 → 2HCl
Predict the product of the reaction between hydrogen and fluorine
Hydrogen fluoride (HF)
When does halogen displacement reaction occur?
When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.
Why will halogen A only be displaced by halogen B if B is above A in group 7?
The most reactive halogen (B) will displace the less reactive halogen (A) to become part of the ionic compound. Reactivity increases as you go up the group so B must be higher in group 7 to be more reactive than A.
Which halogens can chlorine displace from an aqueous ionic solution?
Chlorine can displace any halogens below it in group 7. It will displace iodine and bromine.