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QUESTIONS:
2013; 1c
The Periodic Table
N 7 14 Nitrogen • 
The periodic table contains all of the known elements
arranged in a specific way, according to their atomic
structures
• 
Each element is represented by a letter/letters
corresponding to their name
• 
Be aware that some letters do not correspond to the
English name for that element (For example Pb is
lead)
• 
Each element will have two numbers written beside
it. The smaller one corresponds to the atomic
number whilst the larger one is the mass number.
• 
Elements are arranged horizontally in ‘periods’. Each
element in a specific period has the same number of
electron shells
• 
Elements are arranged vertically in ‘groups’. Each
element in a specific group has the same number of
electrons in its outer/valence shell
© StudyTime 2015
Practice Question
Use the position of Magnesium on the periodic table to justify how many electrons it
has. Use this to explain the electron configuration of a Magnesium atom
12 24 d
Mg
v t
Magnesium Magnesium is located three rows down and two columns across in the periodic table. This means that it is located in the third period and the second group. From this informa>on, we can tell that Magnesium has three electron shells, the last of which contains 2 electrons. We can assume that the first two electron shells are full with 2 electrons and 8 electrons. Adding these together, we get a total number of ( 2 + 8 + 2 = 12 electrons) and an electron configura>on of 2, 8, 2. This claim can be backed up by the atomic number of Magnesium, which is 12. © StudyTime 2015
QUESTIONS:
2014; 1b
2013; 1a
• 
Atomic Structure
All atoms consist of three types of subatomic
particles. The relative numbers of these defines
which element the atom is as well as its physical and
chemical characteristics
• 
Protons and Neutrons both exist in the dense central
nucleus of the atom. Protons are positively charged
whilst neutrons have no charge
• 
Electrons circulate the outside of the nucleus and are
negatively charged. They exist in shells/orbits which
are constantly moving.
• 
The outer electron shell of an atom defines most of
its chemical properties. This shell is known as the
‘valence shell’
• 
The mass number of an atom tells us how many
particles exist in the nucleus of an atom. It is
therefore a sum of the number of protons and
neutrons
• 
The atomic number of an atom tells us how many
protons there are in an atom
• 
Atoms are neutrally charged and have equal
numbers of protons and electrons
© StudyTime 2015
Practice Question
Describe the number of subatomic particles present in an atom of Carbon
d
6 12 C v t
Carbon Carbon has a mass number of 12. This means that there are 12 subatomic par>cles in the carbon nucleus. Carbon also has an atomic number of 6. This means it has 6 protons. Because the mass number is the sum of protons and neutrons, we know that Carbon has ( 12 – 6 = 6 neutrons). Because we are referring to an atom, we know that there is no overall charge. This means that there must be an equal number of protons and electrons present. Because of this, Carbon has 6 protons, 6 neutrons and 6 electrons. © StudyTime 2015
QUESTIONS:
2014; 1b
2013; 1a
Electron Shells
• 
Electrons are arranged in shells around the central
nucleus. Each shell holds a maximum number of
electrons
• 
The outer electron shell of an atom defines most of
its chemical properties. This shell is known as the
‘valence shell’
• 
The first shell is held very close to the central
nucleus and can only hold two electrons
• 
• 
The next two shells are much bigger and can hold 8
electrons each
Electrons evenly arrange themselves in pairs across
the shell. Repelling each other as they are all
negatively charged.
• 
The electron ‘arrangement’ or ‘configuration’ of an
atom describes how many electrons it has in each
shell. An example is Magnesium, which has the
arrangement: 2, 8, 2.
• 
The atom makes sure each electron shell is filled to
its maximum before the next shell begins to be filled
© StudyTime 2015
Practice Question
For the following atoms, give the correct electron configuration
Atom Atomic Number Electron Configura4on t
Helium 2 2 Boron 5 2, 3 Oxygen 8 2, 6 Silicon 14 2, 8, 4 Phosphorus 15 2, 8, 5 © StudyTime 2015
Isotopes
7 14 N 7 15 Nitrogen • 
Isotopes are atoms of the same element with
identical atomic numbers, but differing mass
numbers
• 
This means they have the same number of protons
and electrons, but different numbers or neutrons
N Nitrogen • 
Because neutrons have no charge and do not
contribute to the chemical properties of an atom,
different isotopes will behave the same in chemical
reactions
• 
Because neutrons contribute a small amount of
mass to an atom, different isotopes of the same atom
may have different physical properties (i.e boiling
temperature)
© StudyTime 2015
Practice Question
Two isotopes of Carbon can be found in nature. Describe the similarities and
differences between the two atoms.
d
6 12 C v t
Carbon 6 13 C Carbon Both atoms have the same atomic number. Because different elements are defined by their atomic number, we can say that both isotopes are the element Carbon. This means they have the same number of protons and electrons as each other and will hence behave the same in chemical reac>ons. However, Carbon-­‐13 has one more neutron than Carbon-­‐12. This means that Carbon-­‐13 will have a slightly heavier atomic mass. Because of this, Carbon-­‐13 may behave slightly differently in physical reac>ons such as mel>ng and boiling. © StudyTime 2015
QUESTIONS:
2013; 1b
Ions
Na
+ • 
While atoms on the periodic table have no charge,
most of them are not stable
• 
In order for an atom to be stable, it must have a full
valence electron shell. In the case of atoms, this only
covers the noble gases (last group of the periodic
table)
• 
Atoms can become ‘stable’ by losing or gaining
electrons in order to have a full outer electron shell
• 
Because they are losing/gaining negative electrons
while maintaining the same amount of positive
protons, they gain a positive or negative charge and
are no longer neutral. An atom that is no longer
neutral is called an ion.
• 
Metals typically lose electrons to form positive ions,
whilst non-metals tend to gain electrons to form
negative ions
© StudyTime 2015
Practice Question
Describe the new electron configuration and charges on the following atoms
Atom Atomic Number Atomic Electron Configura4on Ionic charge Ionic Electron Configura4on Helium 2 2 0 2 Boron 5 2, 3 3+ 2 Oxygen 8 2, 6 2-­‐ 2, 8 Phosphorus 15 2, 8, 5 3-­‐ 2, 8, 8 t
© StudyTime 2015
Ionic Bonding
Na + Cl
+ • 
-­‐ In order for an atom to lose or gain electrons to form
an ion, it must have a place to leave/gain the
electrons from
• 
Ionic bonds are a very strong form of bond as they
involve the donation and acceptance of electrons
• 
These places are found in other atoms through an
ionic bond
• 
• 
An ionic bond is a bond between a metal and a nonmetal, where the metal donates electrons and the
non-metal picks them up
Ionic compounds therefore have high melting and
boiling points, and are unlikely to dissociate easily in
water
© StudyTime 2015
Practice Question
Neither oxygen nor magnesium are stable atoms. However, they each form ions with
different charges. Explain how this difference means they can form an ionic bond.
8 d
O
v t
Oxygen 12 Mg
Magnesium Neither Oxygen nor Magnesium have full valence electron shells. Because of this, they must each lose or gain electrons in order to become stable. Oxygen has 8 electrons and hence an electron arrangement of 2, 6. This means it has 6 electrons in its valence shell. It must hence gain 2 electrons to have an outer shell of 8 electrons. Magnesium has 12 electrons and an electron arrangement of 2, 8, 2. It must hence lose 2 electrons to have a full valence shell of 8 electrons. During an ionic bond, Magnesium donates these two electrons to Oxygen, sa>sfying both atoms and forming a strong bond. © StudyTime 2015
QUESTIONS:
2014; 1a, c
Using an ion table
+1
• 
• 
• 
Ion tables give the ionic charge formed on the ions of
all of the atoms you will come across in your exam
They are arranged in columns depending on the
charges they form. All of the ions in each column
originate as atoms from the same group of the
periodic table.
Ion tables refer to each ion by its chemical symbol,
not by the name of the ion. This means you must be
familiar with the symbol for each atom, as well as its
name for the exam.
• 
Ionic bonds must have an even number of electrons
being donated an accepted. This means that an ion
donating 2 electrons must interact with two ions
accepting 1 electron.
• 
The process of making sure the same amount of
electrons are donated and accepted is known as
balancing equations
© StudyTime 2015
Practice Question
How many Chloride ions will each of the following ions need to interact with to form an
Ionic bond? (The Chloride ion has a charge of -1)
Atom Atomic Number Atomic Electron Configura4on Ionic charge Number of Chloride ions Magnesium 12 2, 8, 2 2+ 2 Boron 5 2, 3 3+ 3 Beryllium 4 2, 2 2+ 2 Potassium 19 2, 8, 5 1+ 1 t
© StudyTime 2015
QUESTIONS:
2014; 3c
Acids
H2SO4
• 
Acids are characterised by having excess Hydrogen
atoms attached to them. These Hydrogen atoms are
used to donate protons during chemical reactions.
• 
Common acids you may come across include sulfuric
acid, nitric acid and hydrochloric acid.
• 
Acids have a pH of below 7. The lower the pH, the
stronger the acid is.
• 
Acids commonly react with bases to form a salt and
water.
• 
Acids can also react with metals to form a salt and
hydrogen, and carbonates to form carbon dioxide,
water and a salt
© StudyTime 2015
Practice Question
Write the products formed in the following acid reactions
Acid Second Reactant Product(s) t
Sulfuric Acid Zinc Zinc Sulfate, Hydrogen Nitric Acid Sodium Hydroxide Sodium Nitrate, Water Hydrochloric Acid Potassium Carbonate Carbon Dioxide, Water, Potassium Chloride © StudyTime 2015
QUESTIONS:
2014; 3a, b
2012; 3b, c
Indicators
1 • 
There are two main indicators used in level 1 that tell
how acidic a compound is
• 
Litmus paper can tell whether a solution is acidic,
basic or neutral but not how strong an acid or base it
is
• 
An acid will turn blue litmus paper red, whilst a base
will turn red litmus paper blue
7 14 • 
Universal indicator can be used to tell roughly how
acidic or basic a compound is
• 
A few drops of universal indicator will turn a solution
somewhere on the spectrum from red to blue/purple.
The more red a solution is, the more acidic it is. The
more blue a solution is, the more basic.
• 
A solution that appears green when universal
indicator is added is considered neutral
© StudyTime 2015
Practice Question
State whether the following observations correlate to an acidic, basic or neutral
solution
Observa4on Red litmus paper remained red, blue litmus paper turned red Conclusion t
Acidic solu>on Red litmus paper remained red, blue litmus paper remained blue Neutral solu>on Universal indicator turned solu>on pink Weak acid Universal indicator turned solu>on dark purple Strong base © StudyTime 2015
QUESTIONS:
2013; 3b
Collision Theory
• 
Collision Theory describes the process of two or
more molecules colliding together in order to make a
chemical reaction proceed
• 
In order for any chemical reaction to occur, these
collisions must be happening
• 
The more collisions there are happening per second,
the faster the reaction will occur
• 
Not all molecular collisions are successful. In order
for a collision to contribute towards a chemical
reaction, the molecules must hit each other at the
correct orientation and must have the correct
amount of energy
• 
The minimum amount of energy required to make a
successful collision occur is known as the ‘activation
energy’
© StudyTime 2015
Practice Question
Chemical reactions do not tend to continue for infinite periods of time – observations
tend to level off once the reaction reaches a certain point. With reference to collision
theory, explain why this is the case.
d
v
In order for chemical reac>ons to occur, molecules must collide with each other at the correct orienta>on and with the minimum amount of necessary energy, known as the ‘ac>va>on energy’. Eventually, every reac>on will reach a point where all of the available molecules have performed collisions with each other. At this point, all of the reactants have been used up and hence no more product can be formed. Once the reac>on has ended, some collisions may occur. However, these collisions will not possess the ac>va>on energy required to help the reac>on proceed any further. © StudyTime 2015
QUESTIONS:
2014; 2a, b
2013; 2a
Rates of Reaction
Fast
• 
• 
While all reactions require successful collisions in
order to occur, there are a number of variables which
dictate how many of these collisions happen. These
variables give the rate of the reaction
The concentration of the reactants effects the rate of
reaction. This is because the higher the
concentration of reactants, the more molecules are
available to collide. This increases the likelihood of
successful collisions occurring
Slow
• 
The temperature the reaction is occurring in effects
the rate of reaction. This is because added heat gives
the molecules more energy. This energy can be used
to overcome the minimum activation energy barrier.
• 
The surface area also has an effect on reaction rate.
This is because the greater the surface area
available, the more molecules are exposed to collide
and the more successful collisions can occur
• 
Catalysts can increase the rate of reaction by
lowering the activation energy needed for collisions
to be successful
© StudyTime 2015
Practice Question
Describe how the following changes to a system effect the colliding molecules, and
use this to state how it effects the rate of reaction
Change Effect on molecules Increase in temperature Molecules gain energy Occurs faster Decrease in concentra>on of one of the reactants Less molecules available to collide Occurs slower Catalyst added Molecules not directly effected. Ac>va>on energy required becomes less Occurs faster t
Large chips of one reactant Increase in surface area broken into smaller pieces leaves more molecules exposed to collide Effect on reac4on rate Occurs faster © StudyTime 2015
QUESTIONS:
2014; 2c
2013; 4c
2012; 2c, 3a
Balancing Equations
2NaCl + MgCO3 Na2CO3 + MgCl2 Coefficient
Subscript
• 
In order to gain full marks for any equation, you must
make sure it is correctly balanced
• 
Coefficients multiply the number of every atom in
that compound by that value.
• 
This includes making sure there are an even number
of each atom on each side of the arrow
• 
It is easiest to begin by balancing the Hydrogen and
Oxygen atoms on each side of the arrow first
• 
When balancing an equation, you are not allowed to
change any of the subscript/small numbers written
beside each individual atom. Instead, you must add
coefficients to each compound
• 
If you think an equation is correctly balanced, make
sure to go back and double check each individual
atom. Don’t be afraid to make a list of the atoms and
keep a written track of how many appear on each
side.
© StudyTime 2015
Practice Question
Balance the following equations:
FeBr3 + H2SO4 d C4H6O3 + H2O Fe2(SO4)3 + HBr C2H4O2 Fe + Cl2 v FeCl3 2FeBr3 + 3H2SO4 Fe2(SO4)3 + 6HBr C4H6O3 + H2O 2C2H4O2 Fe +3 Cl2 2FeCl3 © StudyTime 2015
QUESTIONS:
2012; 2b
Bases
NaOH
• 
Acids are characterised by having excess Hydroxide
(OH-) groups attached to them. These hydroxide
groups can be used to accept protons and form water
(H2O)
• 
Common bases you may come across often end with
the word ‘hydroxide’, ‘oxide’ or ‘carbonate’
• 
Bases have a pH of above 7. The higher the pH, the
stronger the base is.
• 
Bases are able to ‘neutralise’ acids. This takes away
their chemical properties and can make them a lot
safer
• 
Bases commonly react with acids to form a salt and
water.
• 
Bases that do not dissolve when placed in water are
known as ‘Alkalis’. Most bases you will come across
are akalis.
© StudyTime 2015
Practice Question
Hydrochloric acid is a very dangerous acid that can cause burns and corrode
solids. Explain, using the equation below how a base can remove these dangerous
properties.
d
OH-­‐ + vH+ H2O The equa>on above describes the neutralisa>on reac>on between an acid and a base. During this reac>on, an acid such as Hydrochloric Acid dissociates to release a proton in the form of an H+ ion. As this is occurring, an added base such as NaOH is also dissocia>ng to form the OH-­‐ compound ion. The OH-­‐ ion acts as an ‘acceptor’ and is able to bond to the acidic H+ ion in the solu>on. The combina>on of these two ions forms water (H2O). As water is a neutral compound, it possesses no dangerous proper>es such as those present in Hydrochloric Acid. © StudyTime 2015
QUESTIONS:
2014; 2a
Gas Tests
+
H or CO
• 
• 
• 
All chemical reactions result in the formation of
products from reactants. Sometimes, these products
can be hard to identify as they have no distinctive
color or texture
• 
In order to run a test for Hydrogen, collect some of
the unidentified gas in a test tube and trap with a
bung or your finger. Hold a lit match over the test
tube and release the bung. If you hear a ‘pop’ or
‘squeak’ sound, the gas created is Hydrogen
• 
To test for carbon dioxide, bubble the unidentified
gas through lime water. If the lime water turns a
murky/cloudy colour, the gas is carbon dioxide.
An example of this difficulty appears with
distinguishing colorless gases from each other
You may be tested on how to decide whether a gas
produced is Hydrogen or Carbon Dioxide
?
2
© StudyTime 2015
Practice Question
Part of an experiment in class requires you to react calcium carbonate with
Hydrochloric acid. Write a method to determine the gas produced by this reaction,
and explain what you would expect to observe
d
HCl+ CaCO3 ?? 1. 
2. 
3. 
4. 
5. 
Collect a small amount of the gas created by the reac>on in a clean test tube Immediately place a bung over the test tube Light a match over the test tube and quickly remove the bung If you hear a ‘pop’ or ‘squeak’ sound, iden>fy the gas produced as Hydrogen gas If no sound is heard, replace the bung with a tube and place the other end of the tube in a beaker of lime water 6.  If the lime water turns murky/cloudy, iden>fy the gas produced as carbon dioxide As the reac>on involves a carbonate and an acid, I would expect to see carbon dioxide formed. This means that no ‘pop’ sound would be heard, but the limewater would turn cloudy © StudyTime 2015
Measuring
Rates of Reactions
Reaction Progress
QUESTIONS:
2013; 3a, 4d
2012; 4a
Time
• 
• 
The rate of a reaction can be measured by tracking
either the rate of product formation or the rate of
loss of reactant. These measurements are made by
taking readings of the product or reactant at regular
intervals
The rate of reaction can also be roughly measured by
monitoring observations such as color changes. The
faster these observations appear, the quicker the
rate of reaction
• 
The reaction progress is often graphed against time.
The shape of this graph can give information on the
rate of reaction
• 
Reaction graphs tend to have a steep section where
the reaction is occurring the fastest. This levels off
and eventually reaches a plateau once all of the
reactants have been used up
• 
The steeper the initial section of the graph and the
earlier the graph reaches its plateau, the greater the
rate of reaction is
© StudyTime 2015
Practice Question
A reaction between calcium carbonate and hydrochloric acid is performed twice.
Once with crushed calcium carbonate and once with large chunks. Use collision theory
to decide which reaction used the crushed calcium carbonate.
Reaction Progress
d
Reaction 1
Reaction 2
v
Time
Reac>on 1 was performed with the crushed calcium carbonate. This is because collision theory states that the greater the surface area available, the faster the reac>on will occur. This is due to the fact that the more surface area there is exposed, the more molecules are available to react to form products. As crushed calcium carbonate has more surface area, this reac>on will occur faster. In the graph above, reac>on 1 has a steeper gradient. It also reaches a plateau faster than reac>on 2. This indicates that reac>on 1 reaches comple>on first and is hence the faster reac>on. Reac>on 1 therefore involves the crushed calcium carbonate. © StudyTime 2015