Periodicity (not finished) Flashcards
What do all the members of a period have in common
Same number of electron shells
Similar chemical characteristics
What is periodicity
The repeating properties of elements
How do 1st ionisation energies change going down group 2
Getting lower due to the increasing distance between the nucleus and the outer electrons
How do atomic radii change going down group 2
Increasing as there are a greater number of electron shells
How does melting point change going down group 2
Lower as the bond strength is weaker due to the increasing atomic radii
How does electronegativity change going down group 2
Decrease as the ionic radii increases and the outer electrons are further away from the nucleus
How does the reaction with water change going down group 2
More reactive as less energy is required to remove the outer electrons
What is the general equation for the reaction between group 2 metals and water
M + 2H20 -> M(OH)2 + H2
Why are the solutions formed between the reaction of group 2 metals and water alkaline
The formation of OH- ions
Why does the pH of the group 2 hydroxides increase going down the group
More OH- ions in the water
How does the solubility of group 2 hydroxides change going down the group
Become more soluble
How does magnesium react with cold water
Very slowly
How does magnesium react with steam and how do the products of this reaction differ to the reactions of other group 2 metals with cold water
Reacts much faster with steam but no hydroxide is formed as it decomposes
What is the equation of the reaction of magnesium and steam
What are the observations for this reaction
Mg + H20 (g) -> MgO + H2
Burns with a bright white flame to form a white solid
What happens to the group 2 metals when they react with water (OIL RIG)
They are oxidised and lose electrons
What is the equation for the reaction between chlorine and water
Cl2 + H2O -> (reversible) HCl + HOCl
How does the solubility of group 2 sulfates change going down the group
Decreases
Name and explain one use of barium sulfate that relies on it being insoluble
Used in barium meals for aiding diagnosis of problems within the GI tract as it acts as a contrast medium to highlight any abnormalities in soft tissues
What is the basis of the test for sulfates
The fact that barium sulfate is insoluble
Describe the chemical test for sulfates
Add barium chloride and hydrochlorid acid, or barium nitrate and nitric acid. If the unknown is a sulfate, it will give a white ppt of barium sulfate
In the test for sulfates, why is an acid also used (usually HCl)
to get rid of any carbonate, ions, or any other unwanted precipitates which also precipitate in the absence of acid
What would the equation be for the hydrochloric acid reacting with the carbonate in the test for sulfates
2HCl + BaCO3 -> BaCl2 + CO2 + H2O
What are bases
Substances that react with acids to form a salt and water
How can magnesium hydroxide be used as an antacid
Milk of magnesia is an antacid containing a suspension of magnesium hydroxide suspended in a liquid
What is a suspension
Small particles of insoluble solid suspended in a liquid
Why does the magnesium hydroxide in milk of magnesia form a suspension and not a solution
It is insoluble
Why does magnesium hydroxide relieve indigestion
Reacts with excess stomach acid and neutralises it
Which hydroxide be used to treat acidic soils
Calcium hydroxide
What is the equation of calcium hydroxide treating acidic soils
Ca(OH)2 + 2H+ -> Ca2+ + 2H20
Which acidic gas is produced when sulfur in fossil fuels is burnt
Sulfur dioxide
Write an equation for the formation of sulfur dioxide from fossil fuels
S + O2 -> SO2
What environmental issue can sulfur dioxide cause
Acid rain
How do flue gases help to remove SO2
They are passed through filter beds of calcium oxide and react with the SO2 to remove it
Write an equation for the removal of SO2 using flue gases
Calcium carbonate could be used in a similar way
CaO + SO2 -> CaSO3
CaCO3 + SO2 -> CaSO3 + CO2
What are the 2 ways to extract titanium from titanium oxide
Reduction by sodium
Reduction by magnesium
Equation for extraction of titanium with reduction by sodium
TiCl4 + 4Na -> Ti + 4NaCl
Equation for extraction of titanium with reduction by magnesium
TiCl4 + 2Mg -> Ti + 2MgCl2
Why can’t you extract titanium using carbon
Titanium will react with carbon to produce titanium carbide which makes the metal more brittle
How does the extraction of titanium with reduction by sodium work
Titanium chloride added to a reactor with pure sodium
Heated to around 1000 degrees
Left to cool for several days
Mixture is crushed and washed with dilute HCl to remove the sodium chloride
How does the extraction of titanium with reduction by magnesium work
Similar to sodium but just with magnesium
Why is titanium so expensive
Because magnesium is also expensive to extract because electrolysis is required
How does atomic radius change across a period
Gets smaller
What is the definition for electronegativity
The ability for an atom to attract a shared pair of electrons to itself in a covalent bond
Describe the trend in electronegativity across the 3rd period
Increases due to more protons in nucleus, same shielding, smaller atoms and greater attraction
What are the reasons for an ionisation energy requirement drop across a period
A change in electron shell
Electron repulsion
Reaction and equation of sodium with air
Burns with a solid yellow flame to form a white solid
4Na + O2 -> 2Na2O
Reaction and equation of magnesium with air
Burns with a bright white flame to form a white solid
2Mg + O2 -> 2MgO
Reaction and equation of aluminium with air
Aluminium itself doesn’t react because it has an oxide coating. This can be remedied by using aluminium powder (max SA)
Burns with a bright white flame to form a white solid
4Al + 3O2 -> 2AlO3
Reaction and equation of silicon with air
Requires powdered magnesium to reach the required activation energy
Glows red and a white solid is formed
Si + O2 -> SiO2
Reaction and equation of phosphorus with air
Burns with a bright white flame for a prolonged period and forms a white solid
P4 + 5O2 -> P4O10
Reaction and equation of sulfur with air
Burns with a bright blue flame making a colourless choking gas
S + O2 -> SO2
