✅4 - Inorganic Chemistry and the Period Table Flashcards
How does ionisation energy change down group 2?
It decreases
Why does ionisation energy decrease down Group 2?
The extra inner shells shield electrons
Nucleus is further away from outer electrons due to more shells
How does reactivity change down group 2?
Reactivity increases
Why does reactivity increase down group 2?
It becomes easier for the outer electrons to be lost, as they have lower ionisation energies
What do group 2 elements react with?
Water, oxygen and chlorine
What are the group 2 elements?
Beryllium, Magnesium, Calcium, Strontium, Barium (Radium)
What do group 2 elements produce when they react with water?
Hydroxides and hydrogen
Which group 2 elements react with water?
All except Be, Mg reacts very slowly
What do group 2 elements produce when they react with oxygen?
Oxides
What colour are group 2 oxides?
White
What do group 2 elements produce when they react with chlorine?
Chlorides
What colour are group 2 chlorides?
White
Oxides and hydroxides are…
…bases
What happens when group 2 oxides dissolve in water?
They form a strongly alkaline solution due to OH-
What happens when beryllium oxide is added to water?
It doesn’t dissolve, it is insoluble
What happens when magnesium oxide is added to water?
It reacts slowly and isn’t very soluble
When oxides and hydroxides are added to acid, what do they form?
They neutralise the acid to form salts
What is the equation for the reaction between MgO and H2O?
MgO + H2O —-> Mg(OH)2
What is the equation for the reaction between MgO and HCl?
MgO + 2HCl —-> MgCl2 + H2O
Solubility trends of group 2 depend on…
…the anion
If a group 2 compound has a singly charged anion (OH-) how does the solubility change down the group?
It increases
If a group 2 compound has a doubly charged anion (SO4 2-) how does the solubility change down the group?
It decreases
Which group 2 sulfate is insoluble?
Barium Sulfate
How does thermal stability change down group 1 and 2 carbonates and nitrates?
It increases
Why do carbonates and nitrates become more stable down the group?
Large ions have less polarising power so distort the electron cloud less and have a lower charge density. Therefore, they distort the carbonate or nitrate C-O bond or N-O bond less
Which of group 1 and group two compounds are more thermally stable?
Group 1
Why are Group 1 compounds more stable than group 2?
They have a lower charge, so a lower charge density and therefore less polarising power
What do group 2 carbonates decompose to form?
An oxide and carbon dioxide
What is the equation for thermal decomposition of CaCO3?
CaCO3 —-> CaO + CO2
Do group 1 carbonates decompose?
No
What do group 1 nitrates decompose to form?
The Nitrite (NO2) and oxygen
What is the equation for decomposition of Potassium nitrate?
2KNO3 —-> 2KNO2 + O2
What is the exception to the group 1 nitrate decomposition?
Lithium
What does lithium nitrate decompose to form?
LiO2, NO2 and O2
What doe group 2 nitrates decompose to form?
The oxide, nitrogen dioxide and oxygen
What is the equation for the decomposition of Ca(NO3)2?
2Ca(NO3)2 —-> 2CaO + 4NO2 + O2
How can the thermal stability of nitrates be tested?
Measuring how long it takes for a certain amount of oxygen to be produced
OR
How long it takes for brown gas (NO2) to be produced
How can the thermal stability of carbonates be tested?
Measuring how long it takes for a certain amount of CO2 to be produced using lime water
What is the flame colour for Lithium?
Red
What is the flame colour for Sodium?
Orange/Yellow
What is the flame colour for Potassium?
Lilac
What is the flame colour for Rubidium?
Red
What is the flame colour for Caesium?
Blue
What is the flame colour for Calcium?
Brick red
What is the flame colour for Strontium?
Crimson
What is the flame colour for Barium?
Apple green
Why is a colour produced during a flame test?
The electrons are excited to a higher energy level and then as they drop back down, they release the energy in the form of light.
What determines the wavelength of light produced in a flame test?
The difference between the higher and lower energy levels
What is the solubility of halogens?
Low, as they are non polar
What do halogens dissolve easily in?
Cyclohexane
How can halogens be identified when dissolved in organic compounds?
They have distinctive colours
What colour is bromine in hexane?
Orange/Red
What colour is iodine in hexane?
Purple
How does the reactivity of halogens change down the group?
It decreases
How do the melting and boiling points of halogens change down the group?
They increase
Why do melting and boiling points increase down group 7?
There are more electron shells, so greater London forces
What can chlorine displace?
Br- and I-
What can bromine displace?
I-
What redox property do halogens have?
They are reducing agents
How do halogens react with group 1 metals?
They produce halide salts, so the metal is reduced and the halogen oxidised
What is the equation for the reaction between Li and F?
2Li + F2 —-> 2LiF
How do halogens react with group 2 metals?
They form halide salts, where the metal is reduced and the halogen oxidised
What type of reaction occurs between halogens and cold alkalis?
Disproportionation
What is the equation for the reaction between I2 and NaOH?
I2 + 2NaOH —-> NaOI + NaI + H2O
What type of reaction do halogens undergo with hot alkali?
Disproportionation
What compound is used to kill bacteria?
Chlorate (I) - ClO-
How does the reducing power of halides change down the group?
It increases
What is the equation for the reaction between KCl and H2SO4?
KCl + H2SO4 —-> KHSO4 + HCl
What happens during the reaction between KCl and H2SO4?
HCl gas is given off as misty fumes
Cl- aren’t strong enough reducing agents to reduce sulfuric acid, so reaction stops there
Not a redox reaction
What are the equations for the reaction between KBr and H2SO4?
KBr + H2SO4 —-> KHSO4 + HBr
2HBr + H2SO4 —-> Br2 + SO2 + 2H2O
What happens during the reaction between KBr and H2SO4?
The first reaction gives misty fumes of HBr
Br- are stronger reducing agents so react with H2SO4 in a redox reaction
The reaction produces fumes of sulfur dioxide and orange fumes of Br2
What are the equations for the reactions between Kl and H2SO4?
KI + H2SO4 —-> KHSO4 + HI
2HI + H2SO4 —-> I2 + SO2 + 2H2O
6HI + SO2 —-> H2S + 3I2 + 2H2O
What happens during the reactions between Kl and H2SO4?
HI gas is produced in the initial reaction
Iodide ions then reduce H2SO4 as before
I- is a strong reducing agent and reduced the SO2 to H2S
What are hydrogen halides?
Acidic gases
How do hydrogen halides behave in water?
The dissolve
How do hydrogen halides react with ammonia?
They give off white fumes of ammonium halides
What colour precipitate does Chlorine give with Silver Nitrate?
White
What colour precipitate does Bromine give with Silver Nitrate?
Cream
What colour precipitate does Iodine give with Silver Nitrate?
Yellow
How does AgCl behave with ammonia?
The precipitate dissolves to give a colourless solution
How does AgBr behave with ammonia?
The precipitate remains unchanged in dilute, but will dissolve in conc ammonia
How does AgI behave with ammonia?
The precipitate will not dissolve, even in conc ammonia
What is the test for carbonates?
Add dilute hydrochloric acid and use lime water to test for any CO2 given off
What is the test for Sulfates?
Add dilute HCl and BaCl2. If a white precipitate forms, a sulfate is present
How is ammonia tested for?
It is alkaline, so damp red litmus paper can be used. If ammonia gas is present, the paper will turn blue
How are ammonium ions tested for?
Add sodium hydroxide and gently heat the mixture. If ammonia is given off, ammonium ions were present