Group 2, The Alkaline Earth Metals 3.2.2 Flashcards
In group 2, the elements are Be Mg Ca Sr and Ba
Which ones are metals in their solid stage and what type of bonding is present
Mg -> Ba
Metallic bonding
Describe the trend in atom radius going down group 2
Atomic radius increases as there are more shells of electrons making the atom bigger
Describe the trend in first ionisation energy going down Group 2
Decreases as electrons further from nucleus and outer electrons are more shielded from the nucleus, weaker attraction between nucleus and outer electron so less energy required to remove an electron
Describe the trend in melting point going down Group 2, what is the anomaly
Decreases
Delocalised electrons are further from the nucleus, more sheilding, less attraction between metal ions and delocalosed electrons
Anomaly is magnesium
Explain the reactivity going down Group 2
Increases as there is more shelding so weaker force of attraction between the nucleus and outer electrons so easier to lose electrons to form X²+ ions
What does the reaction of Group 2 Alkaline metals reacting with water depend on
It depends on how easily electrons are lost
What is the general equation for Group 2 Alkaline metals reacting with cold water
X + 2H2O -> X(OH)2 + H2
What is the general equation for Group 2 Alkaline metals reacting with steam
X + H2O -> XO + H2
Describe how Magnesium, calcium strontium and barium react with cold water
Magnesium Reacts very slowly with cold water
Calcium Reacts steadily with cold water
Strontium and Barium react vigorously with cold water
How does magnesium react with cold water compared to steam
Magnesium Reacts very slowly with cold water but quickly with steam
When reacting Group 2 metals with water, hydroxide are produced which make the water…. and the pH is…
Alkaline
pH of 10
What are the observation changes when you react Group 2 metals with water, going down
-Fizzing (more vigorous down group)
-Metal dissolving (faster down group)
-Solution heating up (more down group - exothermic reaction)
-With magnesium and calcium, a white precipitate appears (less precipitate forms down group with other metals)
When group 2 Alkaline metals reacting with water, where does oxidation and reduction occur
Metal is oxidised and loses two electrons
Each Hydrogen in water is reduced and gains an electron each
As you go down group 2 what happens to the solubility of hydroxides
Solubility increases (magnesium and calcium only forms a precipitate)
As you go down group 2, what happens to the solubility of sulphates
Solubility decreases
What is the test for sulphates
Add hcl
Add barium chloride
Sulfates form a white precipitate
Why is titanium a useful metal
Abundant
Low density
Corrosion resistant
Give a use for titanium
Used for making strong, light alloys to use in aircarfts
Why can’t titanium be extracted with carbon or electrolysed
Carbon- titanium carbide is formed rather than titanium
Titanium can’t be electrolysed because it has to be very pure
Which group 2 metal is used to extract titanium
Magensium
What steps are involved in the extraction of titanium
-Solid is converted into chloride (liquid state)
-Chloride is purified by Fractional distillation in an Argon atmosphere and then is reduced by magnesium
Why is titanium expensive
Magnesium and Argon are expensive
Batch processes
High temperatures required in both steps
What is the use of magnesium hydroxide
In medicine to alleviate constipation and also used in indigestion remedies
What is the use of calcium hydroxide
In agriculture to neutralise acidic soil
If sulfur is present in coal and crude oil, what happens when it burns
It produces sulfur dioxide which dissolves in moisture to form acid rain
How can you prevent the formation of sulfur dioxide gas
Can be removed from power station chimneys by reacting with calcium oxide
What is the use of barium
Diagnose problems with the the digestive system
Barium 2+ ions are toxic but why is this technique harmless
They are Insoluble so won’t pass into the bloodstream
What are the 3 stages in chlorination of alkanes
Initiation
Propagation
Termination
What needs to be present when an alkane Reacts with a halogen
UV light
Explain initiation in chlorination of alkanes
-Chlorine moelciles gain energy from UV light tk break the Cl-Cl covalent bond symmetrically
-Each chlorine atom takes one electron from the shared pair of electrons and two chlorine radical atoms are formed
What is homolytic fission
The breaking of a covalent bond to form two free radicals
What is the link between intensity of UV light and rate of reaction
As intensity of UV light increases, rate of reaction increases as more free radicals would be produced
What is a free radical
An atom with an unpaired electron
