Download Periodic Table Development Dalton`s Periodic Table Arranged in

Periodic Table Development
Dalton’s Periodic Table
Arranged in order of atomic mass; Symbols are shown for every element
Different names were given(old fashioned)
Newlands Octaves
8 octaves-similar property
Arranged in order of atomic mass; Periodic pattern of properties but this pattern eventually
broke down
Mendeleev’s Table
Combined both of atomic number and octaves
Similar to what we use today
Arranged them so that groups with similar properties fell into vertical columms in the table
Properties of group 0
Helium:protons:2 neutrons:2 electrons:2
Noble gas are stable with a general equivalence of numbers of protons and electrons. They
have a full outer shell which makes them stable and generally unreactive
They were the last elements to be discovered because they are generally unreactive and
they are gases. Colourless and monatomic.
Their boiling point and density increases from top to down. Helium is used to fill airships
Element
Number
of
Density
Boiling point
Uses
electrons
He
2
4
Intermolecular
Party balloons
Ne
10
20
Forces
Car light
Ar
18
40
Increases
Double-blazing
Kr
36
84
When
Anesthetic
Xe
54
131
Going
Car light
Rn
86
222
Downwards
Radiotherapy
Group 1
Alkali metals
Coated in oil to stop them from reacting
1 electron in the outer shell
Lithium 3 protons 4 neutrons and 3 electrons
Sodium 11 protons 12 neutrons and 11 electrons
Potassium 19 protons 20 neutrons and 19 electrons
More reactive as you go down the group as the nucleus is positive, electron is further away
This is the same for all elements in groups.
Hydrogen: lit splint and squeaky pop
Less attraction between outer shell and electron
The melting and boiling points decrease as there is less energy needed to boil the electron
Group 7-halogens
Sodium+chloride-sodium chloride
Fluorine
Chlorine
Proton
9
17
Neutron
10
18.5
Electron
9
17
Electronic confirmation
2,7
2,8,7
Elements
Electrons
Density
Reactivity
Melting point,
boiling point
Fluorine(gas)
9
Increases
Decreases
Increases
Iodine(gas)
53
As
As
As
Chlorine(g)
17
You
You
You
Bromine(aqueous)
35
Go
Go
Go
Astatine(solid)
85
Down
Down
Down
Reactivity down the group decreases; harder to gain electrons as the atom gets bigger.
More outer shells
Fluorine isn’t used a lot; too reactive
Chlorine-used in swimming pools kill bacteria
When group 1 reacts with group 7, a metal halide is formed
Transition metals
Name of compound
Formula
Description
Nickel sulphate
NiSO4
Green, toxic, aqueous
Copper chloride
CuCl2
Blue
Cobalt chloride
CoCl2
Pink/red toxic
Chromium chloride
CrCl
Black/dark
Iron chloride
FeCl2
Yellow Fe3+ Cl-
Name of metal
Can it be bent?
Can
it
float
on
Description
water?
Copper
Yes
No
Zinc
Yes
No
Iron
Yes
No
Conclusion: most of the transition metal compounds have colour.
Dense metals,strong,good conductor, high boiling points
Structure of metals: metallic bonding
+-+-+-+-+-+-+-+-+-+
Strong electrostatic forces of attraction
More neutrons, more protons between oppositely charged ions
Dull grey
The electrons on the outer shell all go through the same energy level, for example:3D
HARD water
Hard water contains ions that exchange ions that can damage the pipes and applicances
Rainwater is naturally weak acidic
Therefore it can dissolve minerals from rocks.
Carbonic acid+ calcium carbonate=calcium hydrogen carbonate
H2CO3(aq)+CaCO3(s)=Ca(HCO3)2 (aq)
The presence of calcium ion and magnesium ions in the water makes it hard.
The type of rock will determine whether it is hard or soft water
Soft water readily forms lather with soap, but it is more difficult to form lather with hard
water.
Soft water exists in Cornwall, Wales and Lake District, it has low levels of dissolved calcium
and magnesium compounds, while the water in other parts of the country have hard water
because it has higher levels of dissolved calcium and magnesium compounds.
Soft water will make appliances last longer
Hard water: water that contains magnesium and calcium ions and does not readily form
lather with soap.
Soft water: water that readily forms lather with soap
Scum;insoluble precipitate that forms with soap and hard water
Removing hard water
Temporary and permanent hard water
Formation of limescale on the inside of the kettle softens the water( removes Mg, Ca ions)
Permanent hard water softens from sulphate cannot be removed by heating. But we can
soften it by adding sodium
Temporary:Ca2+ + 2HCO3=CaCO3+ H2O+CO2
1. Boiling the hard water containing hydrogencarbonate ions
2. Carbonate io0ns react with Ca/Mg
Therefore removing using washing soda adding sodium carbonate
This is the same reaction as formation of limescale but this time it happens where and
when we want it to.
Hard water ions are swapping places with soft water such as Sodium and potassium
Most hard water makes it difficult to wash ourselves.
As well as this, it also makes it difficult to clear the bath/sink when we have finished. This
is because hard water contains dissolved compounds that react with the soap to form scum.
The scum floats on the water and sticks to the bath.
Calcium carbonate reacts with the weakly acidic solution.
The calcium hydrogencarbonate formed is soluble in water, therefore calcium ions,
Ca2+(aq) get into the water, making it hard. This equation describes what happens:
CaCO3(S)+H2O(AQ)+CO2(AQ)=Ca2+(aq)+2HCO3(AQ)
Calcium ions in drinking water helps in the development in strong bones and teeth.
There is also evidence that hard water helps to reduce heart disease
Sodium
stearate(soap)+Ca2+
ions
(calcium)=
calcium
stearate
precipitate
(scum)+Na+ions soluble in water
Hard water contains calcium and for magnesium ions.
These react with soap to form scum. Hard water can also produce scale when it is heated.
This is a poor conductor of energy and makes kettle and water heaters less efficient.
Hard water is better for teeth and bones than soft water. This helps reduce heart disease.
Calcium is dissolved from rocks which are washed into the river, into the sea and
evaporated into the clouds which will rain, this could contain hard water.
2HCO3(AQ)+CO3-(AQ)=H2O(L)+CO2(G)
Purification of water
Clean water is water without harmful bacteria debris or sediment in it.
1. The screen take out the large debris to make the water clean of big rocks.
2. The settlement tank produces sedimentation and the water gets to take out from the
top to get away.
3. Al2(SO4)2+ lime will coagulate small particles in order for them to be filtered through
the fine filter
4. Chlorine is added and Ph is then checked for the safety of home water
Calorimetry
Q=m*Ct
Energy change=mass*specific heat capacity*temperature change
Exothermic VS Endothermic
Breaking a bond requires energy. Making a bond releases energy.
To measure the amount of energy released when a fuel is burnt, you can simply burn the
fuel and use the flame to heat up some water, this is called calorimetry
1. Put 50g of water in a copper can and record its temperature(copper is used because it
conducts heat so well)
2. Weigh a spirit burner containing methylated spirits, along with its lid.
3. Put the spirit burner underneath the can, and light the wick. Heat the water, stirring
constantly, until the temperature reaches about 50oc
4. Use the lid of the spirit burner to put out the flame and measure the final temperature
of the water
5. Weigh the spirit burner and lid again
Calorimetry of solutions
Minimise flame disturbance
Ensure complete combustion
Calorimeter- put a lid on it
Polystyrene cup lets no energy out
Have the same specific heat capacity as water
Stir to make sure chemicals are mixed properly
(assuming polystyrene cup does not leak out heat)
Effect of catalysts
Bond breaking=energy in endothermic
Bond making=energy out, exothermic
For a reaction to happen particles need to collide with each other with enough energy to
break bonds
Catalysts are specific for each reaction-provide a lower activation energy-lower energy
requirements
Catalysts help to control reactions, they are very expensive, often precious metals.
During the reaction catalysts aren’t used up
Hydrogen as a fuel
Burning fossil fuels release carbon dioxide which cause global warming, increasing the
temperatures causing destruction of habitats and causing early migration. Burning fossil
fuel releases sulfur dioxide which cause acid rain. This also makes nitrogen dioxide which
cause smog, blocks out sunlight and damage lungs.
2H2+O2=2H2O
Advantages:
Environmentally friendly
More efficient than petrol and diesel
Only exhumes water
Disadvantages:
Very flammable; may explode
Expensive fuel of hydrogen
Can’t drive it for long distances
Can’t find hydrogen taps in petrol stations; The car is quite expensive
The advantages of using hydrogen are that it is environmentally friendly, a renewable
energy source and has many ways to extract it, no global warming because there is no
carbon dioxide released. Less energy is produced, the gas is explosive; the volume of
storage is big, uses electrolysis to produce hydrogen
All metal ions are positive
Metal ions Colour of flame
Li+
Crimson
K+
Lilac
Na+
Yellow
Ca2+
Red
Ba2+
Green
Method for flame tests
1. Dip the nichrome wire into the concentrated HCl, then dip it into the metal you want to
test
2. Burn the nichrome wire on a Bunsen burner, then identify the colour
Get equipment
1. Dip in HCl to clean nichrome wire
2. Place in flame to dry HCl
3. Place in HCl/ water to ensure powder sticks
4. Place in flame, observe colour
5. Use colour to identify + ions
Test for negative ions
Test for halides
Dilute nitric acid(HNO3) followed by silver nitrate(AgNO3)
Name of compound
Effect of adding HNO3+AgNO3
KI
Yellow silver iodide
KB
Cream silver bromide
KCl
White silver chloride
Titrations
Burette
Rinse through acid first
Fill at a safe height
Shut tap when filling
Make sure tap is full
Watch for air bubbles
Precision: read to 2 decimal places, for example 10.05 can be 0/5
Pipette
Rinse with alkali first
Fill to line meniscus
Do not hold the bulb
Watch for air bubbles
A titration is used to measure accurately how much acid is needed to react completely with
a known amount of alkali-this is used to work out the concentration
HCl+NaOH=H2O+NaCl
Hydrochloric acid+ sodium hydroxide=water+ sodium chloride
Method：
Rinse burette with water and then rinse with acid/alkali
Fill the burette with the acid until it reaches 0.
Use pipette to measure out 25ml of the unknown alkaline and put it into a conical flask
Add indicators to the flask
Use burette to fill flask with acid until indicator becomes neutral
Equilibrium and reversible reactions
a reversible reaction is a reaction that goes in both directions
dynamic equilibrium is a balance between continuous chemical processes
Closed systems: reactant and products remain in one reaction
We can change equilibrium by changing temperature and pressures
Changing temperatures
A+B=C+D
Reversible reactions are always exothermic in one direction and endothermic in the other
direction
If you raise the temperature favours the endothermic direction
So that it uses up extra heat and keep equilibrium in the same direction
Decrease temperature favours exothermic
We can alter the position of the equilibrium if we continue to decrease or increase the
temperature or pressure
The Haber Process
Ammonia is an important compound in the manufacturing of fertilizer and other chemicals
such as cleaning fluids and floor waxes
It is made industrially by reacting nitrogen in the Haber process. It is a reversible reaction
as it never goes into completion
Nitrogen+Hydrogen=Ammonia
N2+ 3H2 =2NH3
Steam is reacted with methane to make hydrogen
Hydrogen is mixed with nitrogen, obtained from air.
The gases are compressed to 200 atmospheres, heated to 450oc
The gases are passed over an iron catalyst
Ammonia gas is produced, then cooled into a liquid
Liquid ammonia is pumped off to be sold
Unreacted nitrogen and hydrogen are recycled.
Compromise due to the cost of machinery
Includes pressure favour forward reaction due to fewer molecules
Adding heat favours the endothermic reaction(backwards)
But if we cooled the reaction down, the rate of reaction would be too slow so we increase
temperature to increase rate of reaction
Compromise between maximum yield and rate of reaction
Iron catalyst: speeds up rate of reaction by creating an alternative pathway with lower
activation energy, makes it cheaper
We do not lower the temperature because we do not lower the rate of reaction.
We do not increase the pressure because it is too expensive
Alcohols
CH4 Methane
C2H6 Ethane
C3H8 Propane
More carbons, the longer chain length, longer intermolecular force. Length of carbon chain
and boiling points.
As we increase chain length, the stronger intermolecular force.
Length of carbon chain and boiling point
Alkanes and alkenes
C2H5OH Ethanol -OH: functional group for alcohols
Alcohol could heighten aggression
Lack of coordination causes dehydration, irreversibly kills liver
Homologus series: group of compounds which contain same things
For example: propanol, ethanol and methanol
Homologous: general formula of alcohol
Alkane CnH2n+2
Alkene CnH2n
Alcohol CnH2n+1OH
Alcohols -take 2
Alcohols are fuels
Methanol+ oxygen=carbon dioxide+ water
2CH3OH+3O2=2CO2+4H2O
Ethanol+ oxygen= carbon dioxide+ water
2CH3OH+ 3O2= 2CO2+ 4H2O
Ethene+ Steam= ethanol
C2H4+H2O=C2H5OH
Methanol and ethanol can dissolve everything water can and more!
They can dissolve fats which water can’t therefore are very useful in industry
Ethanol is used in perfumes(mixes oils smell and water) Meths-used for cleaning paint,
very poisonous to drink so a purply dye is added
The first four alcohols are soluble in water and form neutral solutions
At the hydrocarbon chains get longer the alcohols become less soluble and very long
hydrocarbon chains tend to be insoluble as they are hydrophobic
2Na+ 2C2H5OH= 2C2H5Ona+ H2
Sodium+ ethanol= sodium ethoxies+ hydrogen
Metal+ alcohol= metal ehoxide+ hydrogen
Carboxylic acid
Ethanoic acid CH3COOH
Homologus series
All acids ionize to give H+
Dissociate less- weaker acids
Carboxylic acid do not fully dissociate
Ionization
Strong red (HCl)
Reactions with carbonates
Acid+ carbonates=salt+ water+ carbon dioxide
Ethanoic acid+ sodium carbonate=sodium ethanoate+ water+ CO2
CH3COOH(aq)+Na2CO3=2CH3COONa+ H2O+ CO2
Ethanoic acid has less hydrogen in the reaction so hydrogen doesn’t fully ionize
Acid+ base=salt+ water
Ethanoic acid is used for flavouring and preservative
Ethanol+ oxygen=ethanoic acid+water
C2H5OH+O2=CH3COOH+H2O
Esters are homologus series of carbon compounds made from carboxylic acids and
alcohols
Alcohol+”-oc-“ acid= ester+ water
Ethanol+ ethanoic acid= ethyl ethanoate and water
Extremely volatile and flammable, so esters are dangerous
Non-toxic=don’t react or dissolve in water
They do dissolve into alcohols and other soluble solvents
A solvent is a liquid that dissolves substances
Some are toxic in large quantities
Flammable and heavier than air
Make long chain esters being polymers.