As-Level Chemistry: Paper 1 with
correct answers and definations
Arranged in periods (rows) and groups (columns) by atomic (proton) number - How is
the periodic table arranged
Have the same number of electrons shells, even if they are not all parts of the s or p
sub-shells - All elements within a period ...
Have the same number of electrons in their outer shell, meaning that they all have
similar properties - All elements within a group ...
Periodicity - The trends in the physical and chemical properties of elements as you go
across the periodic table.
Atomic radius across period 3 - Atomic radius across period 3 goes as follows:
1) As the number of protons increases the further down a period you go, the positive
charge of the nucleus increases
2) And though the amount of electrons increases across a period, they are added to the
outer energy level - So their isn't any extra shielding
3) This means that the electrons are pulled closer to the nucleus, causing the atomic
radius to decrease
4) Therefore, that overall the atomic radius of an atom decreases across period 3 with
the largest radius being the first element, Na, and the smallest being the last element,
Ar
Melting points across a period 3 - The melting point across period 3 goes as follows:
1) At the start with sodium, magnesium and aluminium their melting points increase.
This is because they are metals and have strong electrostatic forces to overcome - The
bonds get stronger by the time you reach Al due to having and more positively charged
nucleus, increased number of delocalised electrons and a decreasing radius
2) From Al to Silicon, the melting point increases further as Si is a macromolecular
substance which has very strong covalent bonds that take a lot of energy to break
3) However, the melting point then drops due to phosphorus, sulfur, chlorine and argon
all being molecular substances. The issue with being that kind of substance is that to
break the bonds apart all you need to do is to overcome the weak Van der Waals forces
- A very easy task
4) The difference in melting points between P, S, Cl and Ar is that some molecules are
bigger than others which leads to slightly greater Van der Waals forces
First ionisation energy across period 3 - First ionisation energy across period 3 goes as
follows:
,1) As you mover across the period, the general trend is for the ionisation energy to
increase - This is due to an increase in number of protons within an atom as you go
across the period which leads to a stronger nuclear attraction
2) The electrons do not counter this increase in protons due to the electrons remaining
in roughly the same energy level which means their is little shielding affect or extra
distance to lessen the attraction from the nucleus - Though there is a dip between
elements in Mg and Al, P and S
3) The issue between Mg and Al is that Al has a 3p outer orbital rather than the 3s on
Mg. Because of this the outer most electron in Al is further away from the nucleus and
has an extra layer of shielding in the form of a 3s
4) As for the drop from P to S, this is because, though the ionised electron come out of
the same sub-shell for both P and S. However, in P case the electron is being removed
from a single occupied shell whereas is is being removed from an orbital containing two
in S. The repulsion between the two electrons means that the electrons are easier to
remove from shared orbital
Increases as you go down the group due to extra electron shells as you go down the
group - Atomic radius across group 2
First Ionisation Energy down Group 2 Alkali Metals - First ionisation energy down Group
2 Alkali Metals goes as follows:
1) The ionisation energy decreases as you go down the group
2) This is due to their being extra shielding for the outermost electrons the further down
the group you go as well as the further distance between the outer electrons
3) These two occurrences out weigh the power of the increasing positively charged
nucleus as you go down the group
How does reactivity change in group 2 elements - Some of the ways that reactivity
changes in group 2 elements are as follows:
1) Their is an increase as you go down the group
2) This is because the ionisation energy needed to carry out a reaction is lower the
further down the group you go - This means you don't have to put in much energy for a
reaction to take place if the element you select is one of the obese further down this
group
Melting point of group 2 metals - The melting points of group 2 metals goes as follows:
1) Overall the melting points of these metals decrease as you go down the group
2) This is because, thought the metal ions get bigger, the number of delocalised
electrons and the charge on the ion doesn't change to keep thing equivalent
3) This larger ionic radius therefore causes the distance between the ions and the
electrons to increase as their are not as many electrons that are able to get just as close
a previously
4) This means that it takes less energy to break the bonds, which means that the
melting point generally decrease as you go down the group - Though this is not the
case for Mg where it melting point is really lower in comparison to those around them
5) The reason for Mg being different is that the arrangement of the metallic ions change
,How do group 2 metals react with water? - The way that group 2 metals react with water
goes as follows:
1) When group 2 metals react, they are oxidised from a state of 0 to +2
2) This means that when they react with water, a metal hydroxide and hydrogen gas is
produced
3) This reaction happens more rapidly as you go down the group due to the ionisation
energy decreasing
4) However, it is important to remember that Beryllium does not react with water as its
ionisation energy is to high
Solubility of group 2 metals - The solubility of group 2 metals goes as follows:
1) This heavily depend on the anion the group 2 metal is attached to
2) If they are connected to OH-, solubility increases down the group as they are
connected to a singly charged negative ion
3) If they are connected to SO4^2- solubility decreases as you go down the group as
they are connected to a doubly charged negative ion
barium sulfate - What group 2 metal sulfate is insoluble in water
Test for sulfate ions - To test for sulfate ions you do as follows:
1) Pour you solution containing sulfate ions into a test tube
2) Use a pipette to add hydrochloric acid and barium chloride to the solution
3) If sulfate ions are present a barium sulfate white precipitate will form
Use of group 2 metals - Some of the uses of group 2 metals are:
1) Barium meals
2) Extraction of titanium
3) Removal of sulfur dioxide from flue gases
4) Acid neutralisers
Barium meals - Barium meals goes as follows:
1) When using X-rays, a doctor can use the machine to detect for where bones are and
whether they are broken or not
2) However, this is not beneficial however should you be looking for soft tissues as they
do not show up
3) Therefore 'barium meals', made up of suspended barium sulfate, are given to the
patient to help diagnose problems with the oesophagus, stomach or intestines by
showing the outlines of these tissues
4) You could only use barium sulfate for this task due to other solutions being poisonous
Extraction of titanium - The extraction of titanium goes as follows:
1) Magnesium is used as part of the process of extracting the titanium from its impure
ore
2) First the ore, TiO2 is converted to titanium(IV) chloride, TiCl4 by heating it with
carbon in a steam of chlorine gas
, 3) The TiCl4 is then purified through fractional distillation before being reduced by Mg in
a furnace at almost 1000 'C
Removal of sulfur dioxide from flue gases - The removal of sulfur dioxide from flue gas
is important when burning fossil fuels to produce electricity as sulfur dioxide pollutes the
atmosphere. The system works as follows:
1) A slurry of calcium carbonate and water is produced
2) When Sulfur dioxide react with this, calcium sulfite is produced which cannot pollute
the atomsophere
Group 2 metals and neutralising acids - Groups 2 metals can neutralise acids due to the
following:
1) Due to being an alkaline earth metal, the elements can be used to neutralise acids
2) An example of this is calcium hydroxide which neutralises acidic soils
3) Another example of this is Magnesium hydroxide which is used as an antacid to
neutralise stomach acid
Group 7 halogens and boiling points - Group 7 halogens and boiling points go as
follows:
1) The boiling point increases as you go down the group
2) This is due to their being greater Van der Waals forces as the size and relative mass
of the molecules increases - This helps to explain why F is a gas at room temperature
whereas I is a solid
Group 7 Halogens and electronegativity - Groups 7 halogens and electronegativity goes
as follow:
1) Electronegativity decreases down the group
2) Though all halogens are extremely electronegative, the larger atoms attract electrons
less than smaller ones
3) This is because their outer electrons are further from the nucleus and more shielded
because they have more inner electrons
F2, pale yellow, gas - Formula, colour, physical state of Fluorine
Cl2, green, gas - Formula, colour, physical state of Chlorine
Br2, red-brown, liquid - Formula, colour, physical state of Bromine
I2, grey, solid - Formula, colour, physical state of Iodine
Group 7 halogens and displacement reactions - Group 7 halogens and displacement
reactions goes as follows:
1) When the halogens react, they gain an electron - This means that they are oxidising
agents
correct answers and definations
Arranged in periods (rows) and groups (columns) by atomic (proton) number - How is
the periodic table arranged
Have the same number of electrons shells, even if they are not all parts of the s or p
sub-shells - All elements within a period ...
Have the same number of electrons in their outer shell, meaning that they all have
similar properties - All elements within a group ...
Periodicity - The trends in the physical and chemical properties of elements as you go
across the periodic table.
Atomic radius across period 3 - Atomic radius across period 3 goes as follows:
1) As the number of protons increases the further down a period you go, the positive
charge of the nucleus increases
2) And though the amount of electrons increases across a period, they are added to the
outer energy level - So their isn't any extra shielding
3) This means that the electrons are pulled closer to the nucleus, causing the atomic
radius to decrease
4) Therefore, that overall the atomic radius of an atom decreases across period 3 with
the largest radius being the first element, Na, and the smallest being the last element,
Ar
Melting points across a period 3 - The melting point across period 3 goes as follows:
1) At the start with sodium, magnesium and aluminium their melting points increase.
This is because they are metals and have strong electrostatic forces to overcome - The
bonds get stronger by the time you reach Al due to having and more positively charged
nucleus, increased number of delocalised electrons and a decreasing radius
2) From Al to Silicon, the melting point increases further as Si is a macromolecular
substance which has very strong covalent bonds that take a lot of energy to break
3) However, the melting point then drops due to phosphorus, sulfur, chlorine and argon
all being molecular substances. The issue with being that kind of substance is that to
break the bonds apart all you need to do is to overcome the weak Van der Waals forces
- A very easy task
4) The difference in melting points between P, S, Cl and Ar is that some molecules are
bigger than others which leads to slightly greater Van der Waals forces
First ionisation energy across period 3 - First ionisation energy across period 3 goes as
follows:
,1) As you mover across the period, the general trend is for the ionisation energy to
increase - This is due to an increase in number of protons within an atom as you go
across the period which leads to a stronger nuclear attraction
2) The electrons do not counter this increase in protons due to the electrons remaining
in roughly the same energy level which means their is little shielding affect or extra
distance to lessen the attraction from the nucleus - Though there is a dip between
elements in Mg and Al, P and S
3) The issue between Mg and Al is that Al has a 3p outer orbital rather than the 3s on
Mg. Because of this the outer most electron in Al is further away from the nucleus and
has an extra layer of shielding in the form of a 3s
4) As for the drop from P to S, this is because, though the ionised electron come out of
the same sub-shell for both P and S. However, in P case the electron is being removed
from a single occupied shell whereas is is being removed from an orbital containing two
in S. The repulsion between the two electrons means that the electrons are easier to
remove from shared orbital
Increases as you go down the group due to extra electron shells as you go down the
group - Atomic radius across group 2
First Ionisation Energy down Group 2 Alkali Metals - First ionisation energy down Group
2 Alkali Metals goes as follows:
1) The ionisation energy decreases as you go down the group
2) This is due to their being extra shielding for the outermost electrons the further down
the group you go as well as the further distance between the outer electrons
3) These two occurrences out weigh the power of the increasing positively charged
nucleus as you go down the group
How does reactivity change in group 2 elements - Some of the ways that reactivity
changes in group 2 elements are as follows:
1) Their is an increase as you go down the group
2) This is because the ionisation energy needed to carry out a reaction is lower the
further down the group you go - This means you don't have to put in much energy for a
reaction to take place if the element you select is one of the obese further down this
group
Melting point of group 2 metals - The melting points of group 2 metals goes as follows:
1) Overall the melting points of these metals decrease as you go down the group
2) This is because, thought the metal ions get bigger, the number of delocalised
electrons and the charge on the ion doesn't change to keep thing equivalent
3) This larger ionic radius therefore causes the distance between the ions and the
electrons to increase as their are not as many electrons that are able to get just as close
a previously
4) This means that it takes less energy to break the bonds, which means that the
melting point generally decrease as you go down the group - Though this is not the
case for Mg where it melting point is really lower in comparison to those around them
5) The reason for Mg being different is that the arrangement of the metallic ions change
,How do group 2 metals react with water? - The way that group 2 metals react with water
goes as follows:
1) When group 2 metals react, they are oxidised from a state of 0 to +2
2) This means that when they react with water, a metal hydroxide and hydrogen gas is
produced
3) This reaction happens more rapidly as you go down the group due to the ionisation
energy decreasing
4) However, it is important to remember that Beryllium does not react with water as its
ionisation energy is to high
Solubility of group 2 metals - The solubility of group 2 metals goes as follows:
1) This heavily depend on the anion the group 2 metal is attached to
2) If they are connected to OH-, solubility increases down the group as they are
connected to a singly charged negative ion
3) If they are connected to SO4^2- solubility decreases as you go down the group as
they are connected to a doubly charged negative ion
barium sulfate - What group 2 metal sulfate is insoluble in water
Test for sulfate ions - To test for sulfate ions you do as follows:
1) Pour you solution containing sulfate ions into a test tube
2) Use a pipette to add hydrochloric acid and barium chloride to the solution
3) If sulfate ions are present a barium sulfate white precipitate will form
Use of group 2 metals - Some of the uses of group 2 metals are:
1) Barium meals
2) Extraction of titanium
3) Removal of sulfur dioxide from flue gases
4) Acid neutralisers
Barium meals - Barium meals goes as follows:
1) When using X-rays, a doctor can use the machine to detect for where bones are and
whether they are broken or not
2) However, this is not beneficial however should you be looking for soft tissues as they
do not show up
3) Therefore 'barium meals', made up of suspended barium sulfate, are given to the
patient to help diagnose problems with the oesophagus, stomach or intestines by
showing the outlines of these tissues
4) You could only use barium sulfate for this task due to other solutions being poisonous
Extraction of titanium - The extraction of titanium goes as follows:
1) Magnesium is used as part of the process of extracting the titanium from its impure
ore
2) First the ore, TiO2 is converted to titanium(IV) chloride, TiCl4 by heating it with
carbon in a steam of chlorine gas
, 3) The TiCl4 is then purified through fractional distillation before being reduced by Mg in
a furnace at almost 1000 'C
Removal of sulfur dioxide from flue gases - The removal of sulfur dioxide from flue gas
is important when burning fossil fuels to produce electricity as sulfur dioxide pollutes the
atmosphere. The system works as follows:
1) A slurry of calcium carbonate and water is produced
2) When Sulfur dioxide react with this, calcium sulfite is produced which cannot pollute
the atomsophere
Group 2 metals and neutralising acids - Groups 2 metals can neutralise acids due to the
following:
1) Due to being an alkaline earth metal, the elements can be used to neutralise acids
2) An example of this is calcium hydroxide which neutralises acidic soils
3) Another example of this is Magnesium hydroxide which is used as an antacid to
neutralise stomach acid
Group 7 halogens and boiling points - Group 7 halogens and boiling points go as
follows:
1) The boiling point increases as you go down the group
2) This is due to their being greater Van der Waals forces as the size and relative mass
of the molecules increases - This helps to explain why F is a gas at room temperature
whereas I is a solid
Group 7 Halogens and electronegativity - Groups 7 halogens and electronegativity goes
as follow:
1) Electronegativity decreases down the group
2) Though all halogens are extremely electronegative, the larger atoms attract electrons
less than smaller ones
3) This is because their outer electrons are further from the nucleus and more shielded
because they have more inner electrons
F2, pale yellow, gas - Formula, colour, physical state of Fluorine
Cl2, green, gas - Formula, colour, physical state of Chlorine
Br2, red-brown, liquid - Formula, colour, physical state of Bromine
I2, grey, solid - Formula, colour, physical state of Iodine
Group 7 halogens and displacement reactions - Group 7 halogens and displacement
reactions goes as follows:
1) When the halogens react, they gain an electron - This means that they are oxidising
agents
