C4 Flashcards
What are the properties of alkali metals
(Group 1)
They react with water to form alkaline solutions
They have the typical properties of metals
They are shiny when freshly cut and good condictors of electricity
They are all soft enough to be cut with a knife
What does the trend going down the alkali metals show
They get softer to cut
Their density increases
Their melting point decreases
Reactivity increases
How do lithium, sodium and potassium react with water
Lithium - fizzes steadily and slowly disappears
sodium - melts into a silvery ball, fizzes vigorously then quickly disappears
Potasium - immediatkey ignites and burns with a lilac flame, the dissapears very quickly
Why does reactivity increase going down group 1
It becomes easier to lose electrons from the outer shell
(Force of attraction to the nucleus is lower, the more electron shells there are)
What is group 2 called
The alkaline earth metals
What are the elements in group 7 called
The halogen
What are the properties of the halogens
They are brittle
Poor conductors of electricity
(Typical non metals)
What are the physical properties of each halogen at room temperature
Fluorine - pale yellow gas
Chlorine - green gas
Bromine - orange / brown liquid
Iodine - shiny grey/black crystalline solid
What trends can be seen going down the group (halogens)
Reactivity decreases
Melting + boiling points increase
Density increases
Why are they called group 7 (halogens
They react with metals to form salts
Why does the reactivity decrease going down the group (non metals)
Going down the group they have more electron shells so the force of attraction between electrons and the nucleus is weaker
What is a displacement reaction
A reaction where a more reactive element displaces a less reactive element from its compound
How can you confirm the order of the halogens reactivitu
Using displacement reactions.
The most reactive will displace all but itself (etc)
What is group 8/0 called
The nobel gasses
What are the properties of the nobel gasses
They are unreactive
All in the gas state at room temperature
They are very light, as their atoms are far apart
They are monatomic, with weak forces of attraction - easily broken
What trends are shown going down group 0
Boiling point increases (forces between atoms get stronger)
Density increased
What does monatomic mean
Existing as single atoms
What does diatomic mean
Containing two atoms
What is the IUPAC group
A numbering system of all groups (including transition metals) 1-18
Why are nobel gasses unreactive
They have full outer shell
What are the properties of the transition metals
Shiny when freshly cut
Good conductor of electricity
Strong
Malleable (can be hammered into shape)
How do the transition metals compare to g1 metals
They are stronger / harder
Have higher densities
Higher melting points
Less reactive than g1 metals
What are the transition metals useful for
Making everyday objects, like copper wire
What are the chemical properties of transition metals
They react very slowly
Iron reacts with oxygen and water to produce rust (hydrated iron (3) oxide
Gold platinum and iridium dont react with oxygen and water
How / where is platinum (trans metal) used as a catalyst
In catalytic converters - convert harmful gasses in car exhausts into less harmful fumes
How many different types of ions can transition metals form
Multiple
E.g iron(II) and iron(III)
How do metals react with water / acids
A metal hydroxide and hydrogen is formed /
//
A salt and hydrogen is produced
What does the rate of reaction tell you
The time the reaction takes shows how reactive the metal is
The quicker the reaction takes the more reactive the metal
How do you test for carbon dioxide
Using limewater (calcium hydroxide solution)
Limewater tuens cloudy white when carbon dioxide is bubbled theough it
This happens as the calcium hydroxide and carbon dioxide react to form water and a white precioitate
How do you test for chlorine
Get a damp piece of blue litmus paper
Hold the container near your substance
If chlorine is present the litmus paper will turn red then bleach white
How should you smell substances in a labratory
With the container away from you, breathe enough air to almost fill your lungs
Then waft the substance towards you and take a small cautious sniff
How do you test for hydrogen
Place a lighted splint near the container
If hydrogen is present it will ignitw with a squeaky pop
How do you test for oxygen
Place a glowing splint in the tube.
If it relights oxygen is present
What is a flame test
A test that helps identify metal ions in compounds from the colour they produce in a flame
In a flame test what colour does lithium give off
Red
In a flame test what colour does sodium give off
Yellow
In a flame test what colour does potassium give off
Lilac
In a flame test what colour does calcium give off
Orange/red
In a flame test what colour does copper give off
Green/blue
How do you do a flame test
First ensure the nichrome wire is clean - by dipping it in HCl until producing a clear flame
Next dip the loop of the wire into your powder or solution
Hold the wire on the edge of the bkue flame on your bunsen burner
Seeing what colour it turns tells you the ions present
What are hydroxide precipitate tests
A chemical test to find the ions in a hydroxide solution by adding sodium hydroxide
What colour is the precipitate of iron(II)
Green
What colour is the precipitate of iron(III)
Orange-brown
What colour is the precipitate of copper
Blue
What colour is the precipitate of calcium
White
What colour is the precipitate of zinc
White
In precipitate tests how do you tell the difference between calcium and zinc
Adding excess sodium hydroxide to the zinc, the zinc hydroxide will become a colourless solution
What type of reaction takes place in precipitate tests
Displacement reactions
How do you detect sulfate ions
Add a few drops of hydrochloric acid to your solution
Then add barium chloride
White precipitate will be shown if sulfate ions are present
What is a carbonate
A substance containing co3^2- ions
What do metal carbonates react with acid to form
A salt carbon dioxide and water
How do you test for carbonate ions
Add an acid (e.g hcl) to the solution
If carbonate ions are present it will bubble
During the reaction it will fizz
You can then test further by boiling it through limewater
What is a sulfate ions
SO4^-2
How do you detect halide ions
Add a small amount of dilute nitric acid
Then add silver nitrate
If a precipitate forms halid ions are present
What precipitate colour is chlorine
White
What precipitate colour is bromine
Cream
What precipitate colour is Iodine
Yellow
What are instrumental methods of analysis
A technique for analysing a substance that depends upon a machine
Why is nitric acid added when finding halide ions
To react with any carbonate ions that may be present
What is a mass spectrometer
A device that measured the masses of atoms and molecules
It analyses the relative amounts of different isotopes of an element
What does each peak in a mass spectrum show
Each peak represents a fraction of the molecule
The peak on the right shows the molecular ion
What are the advantages of instrumental methods of analysis
Sensitivity - instruments can analyse smaller amounts of substances
Accuracy - instruments are very accurate. They can be calibrated using internationally accepted standards
Speed - carry out analyses quickly and can run all the time
How do you interpret a gas chromatogram
Each peak represents a substance present in the mixture
The areas under the peaks show the amount of each substance
What are the axis of a gas chromatogram
Detector response (y)
Retention time (x)
How does a mass spectrometer work
The sample molecules are ionised by the machine, to form molecular ions (e.g OH-)
These may break up to form fragments, which the machine can detect
