Topic 4-Inorganic Chemistry And The Periodic Table Flashcards
What is the test for ammonium compounds?
Gas turns damp red litmus paper blue.
Name the 2 problems with the flame test
Sodium compounds (as impurities) can mask other colours
Subjective —> people have different levels of vision so a word description maybe mean different colours to different people.
What causes the colours in the flame tests?
Electrons can absorb energy and move to higher energy levels.
Instantly returns to ground state which releases energy and sometimes this energy is within the radiation of the visible light spectrum which makes a colour appear.
Define electronegativity.
The ability of an atom to draw a pair of bonding electrons from a covalent bond.
Describe the trends of reactions of group 7 with chlorine.
More vigorous down the group.
Describe the trend in reactions of group 7 with oxygen
More vigorous down the group
How do group 2 elements generally react with water?
What is an exception?
M + H2O —> M(OH)2 + H2
metal + water –>metal hydroxide + hydrogen
Magnesium and steam (reacts slowly) is an exception as it forms Magnesium Oxide and hydrogen
What group 2 oxide doesn’t react with water?
Beryllium
What could Mg(OH)2 be used for and why?
Indigestion tablets as Magnesium Hydroxide is very insoluble so won’t react/dissolve into the body.
What is BaSO4 used for and why?
Barium meal for patients about to have an x-ray as it absorbs the x-rays so can be traced but is insoluble so the toxicity won’t affect the body.
What is the interaction between the nucleus and outer electrons called?
Electrostatic attraction
How does group 2 react with oxygen?
Group 2 metals will BURN in oxygen to form solid white oxides.
How does group 2 react with chlorine?
Group 2 metals form white chlorides when reacting with chlorine.
The oxides form more strongly alkaline solutions a you go ….. the group?
Down the group
Oxides and hydroxides are examples of what?
Bases.
What makes metal hydroxides in solutions strongly alkaline?
The hydroxide ions (OH-).
What will bases do to dilute acids?
Neutralise them.
Name the flame colour of Li, Na,K,Rb,Cs (Group1 )
Li=red Na=yellow K=lilac Rb=red Cs=blue
Name the flame colour of Ca,Sr,and Ba (Group 2)
What are the colours of the other Group 2 elements?
Ca=brick red Sr=crimson Ba=Green No colour (radiation beyond the visible light spectrum)
Name the risks of adding Chlorine to water?
Chlorine gas is toxic
Liquid chlorine burns the eyes and skin
What does adding to water and Chlorine do? (in absence of sunlight)
Cl2 + H2O –> HCl + HClO
which ionises to make CLO- which kills bacteria to clean water!
Name some benefits of water treatment
Kills harmful bacteria
prevents deaths
What do Group 1 carbonates decompose to?
They don’t decompose (thermally stable)
What do Group 2 carbonates decompose to?
Oxides and carbon dioxide.
What do Group 2 Nitrates decompose to?
Oxygen, oxide, nitrogen dioxide
What do group 1 Nitrates decompose to?
Nitrite, oxygen.
Halogens undergo what kind of reaction with COLD ALKALIS?
Disproportionation
Halogens + hot alklais undergo a ……… reaction
disproportionation
Define the general trend of reactivity of Group 7
Less reactive down the group
What trend do melting and boiling points have down Group 7?
Increase down the group
Which species is displaced: halogens/halides
Halogens displace less reactive halides e.g. Cl2 displaces Br- and I-
What colours are Cl2, Br2 and I2 in water?
Cl2= colourless Br2= yellow I2= brown
What colours are Cl2, Br2 and I2 in hexane?
Cl2= colourless
Br2=orange
I2= pink
What colours are Fluorine, Chlorine, Bromine and Iodine at room temperature?
Fluorine = pale yellow Chlorine= green Bromine= red-brown Iodine= grey
What two substances form bleach?
Chlorine + Sodium hydroxide
How can you test the thermal stability of Nitrates?
How long it takes for an amount of NO2 (brown gas) to be produced- toxic
OR
How long it takes for a certain amount of oxygen to be produced? (i.e enough to relight a glowing splint)
How can you test the thermal stability of carbonates?
How long it takes for lime water to turn cloudy.
What is the trend in thermal stability down Group 2?
Increases down group 2 (large cations cause less distortion)
If something is thermally stable, what does this mean in regard to decomposition?
More energy will be needed to decompose something thermally stable.
What do Group 1 and 2 carbonates decompose to?
Group 1 don’t decompose as they’re thermally stable.
Group 2 decompose into Oxides and carbon dioxide.
What do group 1 and 2 Nitrates decompose to?
Group 1 = Nitrite and oxygen
Group 2 = Nitrogen dioxide, oxygen, and oxide.
What ion kills bacteria?
Chlorate (I) ions.
The reducing power of halides …… down the group
The reducing power of halides increases down the group.
Describe the trends in melting points in group two?
Melting point Decreases down the table.
The hydrogen halides react with ammonia to give…
White fumes
What group 2 oxide reacts with water VERY slowly?
Magnesium
Oxides are more strongly alkaline … the group?
Oxides are more strongly alkaline down the group
Which key trends of Group 2 INCREASE DOWN the group?
Reactivity with water Reactivity Solubility with Hydroxides How strongly alkaline Thermal stability
Which key trends of Group 2 decrease down the group/increase up?
Solubility with sulfates
Melting points
Describe why the trend in Group 2 melting points happens?
Group 2 elements decrease in melting point due to the ion cores having LARGER radii therefore electrons experience less attraction to the nuclei making bonding weaker.
Why does reactivity of water ….. down the group?
Reactivity of water increases down the group because they have low ionisation energies so will easily lose their outer electrons.
Ground 2 compounds are …… thermally stable than Group 1 compounds, WHY?
Group 2 compounds are less thermally stable than Group 1 compounds because the greater the charge on the cation, the greater the distortion and the less stable the carbonate/nitrate is.
The reducing power of halides ……. down the group
The reducing power of halides increases down the group.
How do the different halide ions react with silver nitrate
F- = no precipitate Cl- = white precipitate Br- = cream precipitate I- = yellow precipitate
When reacting halide ions with silver nitrate, what do you add before and why?
Add dilute nitric acid to remove ions which may interfere with the reaction.
How will Fluorides and Chlorides react with sulfuric acid?
(could be any gr1 metal)
KF+ H2SO4 –> HF + KHSO4
Chloride is the same
How will Bromides react with sulfuric acid?
KBr + H2SO4 –> HBR + KHSO4
2HBr + H2SO4 –> Br2 + SO2 + 2H2O
How will Iodides react with sulfuric acid?
KI + H2SO4 –> HI + KHSO4
2HI + H2SO4 –> I2 + SO2 + 2H2O
6HI + SO2 –> 3I2 + H2S + 2H2O
What will the observation of AgCl, AgBr and AgI be with ammonia?
AgCl = Dissolve, and form a colourless solution AgBr = Won't dissolve unless ammonia is very concentrated AgI = Won't dissolve even if ammonia is very concentrated.
Why do we further test the halide with silver nitrate solution with ammonia?
As the colours with just silver nitrate can look quite similar. Ammonia helps us be sure which halide we have.
Give two reasons why a bromide ion is a more powerful reducing agent than a chloride ion?
Because the attraction between the nucleus is weaker (due to shielding and the size of the ion increasing)
What would you see if you mixed hydrogen iodide with ammonia?
White fumes
If Bromide is displaced and bromine is formed what colour will the mixture turn?
Orange
If iodide is displaced and iodine is formed what colour will the mixture turn?
Brown
How can you test for sulfates?
Adding Hcl and Barium chloride solution, makes a white precipitate if barium sulfate forms.
The Hcl removes traces of carbonates which would also form a white precip
How can you detect carbonates?
Hydrochloric acid makes carbonates fizz as they give off CO2
How do you properly test for ammonium ions?
Add sodium hydroxide to substance and gently heat it. if this the turns damp red litmus paper blue ammonia is present.
Why does litmus paper need to be damp?
So the gas can dissolve and make the colour change.
What produces orange-brown fumes?
NO2 or Br
What forms steamy fumes in moist air?
Hydrogen halides can dissolve in water and moisture in air to produce musty fumes of acidic gas.
HCl + NH3 would produce what observation?
White smoke
What anion after heating gives a brown gas?
NO3-
How can you describe the “reducing power” of something?
The ability for a substance to REDUCE something else (give an electron to something else)
Going down Group 7 from chlorine to iodine the …….. power of the halide ion increases
the reducing power of the halide ion increases.
When iodide ions are added to a solution of chlorine a …… colour appears/disappears?
brown APPEARS
Halide ions act as …….. agents by ……. an electron. Therefore the best halide ion for this is
Halide ions act as REDUCING AGENTS by LOSING an electron
Iodide as attraction=weaker down group so electron lost more easily
Give an equation for hot alkalis reacting with a halogen
3Cl2 + 6NaOH –> NaClO3 + 5NaCl + 3H2O
Give an equation for cold alkalis reacting with a halogen.
Br2 + 2NaOH —> NaOBr + NaBr + H2O
Show Chlorine and Sodium Hydroxide reacting to form bleach.
Cl2 + 2NaOH –> NaClO + NaCl + H2O
Cold dilute NaOH
