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Year 10 Chemistry
Unit 1 : Groups of the Periodic Table
Homework Booklet 1
Lesson Title
Homework
HW 1a
Writing the formula of ionic compounds
HW 1b
Covalent bonding follow up
HW 2a
The truth about bonding and structure
HW 2b
What type of structure
HW 3a
ONLINE : Google Form quiz
HW 3b
How does boiling point vary with number of electrons
HW 3c
Group 7 displacement reactions (equations)
HW 4a
Potassium – needed by nerves, plants & spaceships
HW 4b
Atom versus ion (Group 1)
HW 4c
Group 1 equations
HW 5a
Explaining reactivity (Group 7)
HW 5b
Group 1 – explaining what happens
Summaries
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Page
3-4
4-6
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8-9
10-11
12-13
14-16
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18-19
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22-24
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HW 1a:
writing the formula of ionic compounds
Common ions
+ ion
names
+ ions
- ions
(formula & charge)
(formula & charge)
H+
Cl-
Ag+
Br-
Li+
OH-
Na+
NO3-
Mg2+
SO42-
Ca2+
CO32-
Zn2+
PO43-
- ion
names
Cu2+
Fe2+
(iron II)
Fe3+
(iron III)
Al3+
Formulae of ionic compounds
Select the correct formulae, by looking at the charges and getting the total + charge to equal the
total - charge, from the four choices for each question
Task 1
a] Lithium nitrate
LiNO3
Li2NO3
Li(NO3)2
Li2(NO3)2
Ag2Br2
AgBr2
Ag2Br
Na2SO4
Na(SO4)2
Na3SO4
b] Silver bromide
AgBr
c] Sodium sulphate
NaSO4
3
d] Calcium hydroxide
CaOH
Ca2OH
Ca(OH)2
Ca(OH)3
Al(SO4)2
Al2SO4
Al2(SO4)3
e] Aluminium sulphate
AlSO4
Task 2:
Revise the name, formula and charge of the common ions in the table, for a short recall QUIZ
Carbonate CO32-
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HW1b: covalent bonding follow up
1. The hydrogen halides (hydrogen fluoride, hydrogen chloride, hydrogen bromide and hydrogen
iodide) are important chemicals.
The diagram below represents a molecule of hydrogen chloride.
(i)
What type of particles are represented by the crosses (X)?
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(1)
(ii)
What type of chemical bond holds the atoms in this molecule together?
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(1)
(iii)
Would you expect hydrogen chloride to be a gas, a liquid or a solid, at room temperature
and pressure? Explain your answer. [3]
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2. Chlorine will combine with the non-metal element, carbon, to form this molecular compound:
(a)
What is the symbol equation for the formation of this molecule
(include state symbols) ? [1]
(b)
Explain how these bonds are formed.
(You may use a diagram). [2]
3. (a)
The diagrams represent the atomic structures of two gases, hydrogen and helium.
Hydrogen gas is made up of diatomic molecules (molecules with two atoms).
Helium gas exists as single atoms.
(i)
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How is a molecule of hydrogen formed from two hydrogen atoms?
(You may use a diagram as part of your answer) [2]
(ii)
Why does helium exist only as single atoms?
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(2)
(b)
Hydrogen combines with carbon to form methane.
Each molecule contains four hydrogen atoms strongly bonded to a carbon atom.
Explain why methane has a low boiling point
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(2)
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HW 2a:
The truth about bonding and structure QUIZ
This quiz challenges your understanding of bonding between atoms and the structures formed, checking for misconceptions
TRUE
As a solid (Qs 1- 4)
Each sodium ion is attracted to one chloride ion.
1
2
The ions exist in pairs containing one sodium ion and one chloride ion.
3
Each sodium ion is bonded ionically to one chloride ion, and then to
others by attractive forces.
The sodium ions and chloride ions are not joined to each other, but
are attracted to each other by electrostatic attraction.
4
Dissolved in water (Qs 6 - 8)
The sodium and chloride ions move around in Na+ Cl– pairs.
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6
The solution conducts electricity because electrons can pass through
the solution.
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Sodium chloride dissolves in water because the ions are attracted to
the water molecules
Covalently bonded substances (Qs 8 - 16)
Methane is a gas at room temperature because it contains 4 hydrogen
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atoms
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Methane (CH4) is a gas at room temperature because it has such a
high boiling point
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Ethane (C2H6) has a higher boiling point than methane (CH4) because
there are more covalent bonds to break.
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Methane has a very low solubility in water because the molecules are
attracted to the water molecules.
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Methane does not conduct electricity because there are no charged
particles to move and carry the electricity
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Diamond has a high melting point because the atoms are all joined by
covalent bonds in a 3d lattice
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Graphite doesn’t conduct electricity because the carbon atoms are
covalently bonded
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Diamond is a very strong material due to the fact that all carbon atoms
are covalently bonded to 4 other carbon atoms
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Graphite is used in pencils because it takes little force to break the
covalent bonds within its layers
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FALSE
MARK
HW 2b: what type of structure ?
Using the information below decide what type of structure each of the following substances might
have. This activity is about interpreting data and applying what you know to new situations.
Simple molecular (like CO2)
or Giant
Fill in the last column in the table below.
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ionic (like NaCl)
or Giant
covalent (like graphite).
How did you decide the type of structure for each substance ?
What general information (like low boiling point etc…) did you use to make your
decision …..?
Simple Molecular
Examples
Information to help
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Giant covalent
Examples
Giant Ionic
Examples
HW 3b:
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How does boiling point vary with number of electrons ?
Task:
1] Draw an appropriate line graph to show boiling point against number of electrons.
Label the axes appropriately.
2] Describe the trend (shown by your line) in your own words:
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3] Use ideas about electrons, IMF and energy to explain the trend shown by your graph line.
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4a] In 2010, Scientists artificially produced 6 atoms of a new element by bombarding 22 milligrams
of Berkelium-249 were bombarded by atoms of Calcium-48. The element was named Tennessine
(Ts) and was found to have an atomic number of 117. It was placed at the bottom of group 7 in the
periodic table.
Use your graph to predict the boiling point of a diatomic molecule of Tennessine.
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4b] What other information do scientists need in order to know whether Tennessine should be
placed in group 7 with the halogens ?
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HW 3c :
Group 7 displacement reactions
This is a halogen displacement reaction :
I2 (aq) + 2LiAt (aq)  At2 (aq) + 2LiI
(aq)
a) Why is lithium astatide used “in solution” for this reaction, as it would normally be a solid at room
temperature and pressure.
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b) What would you SEE happening at this reaction takes place ?
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c) Suggest why iodine is used in solution for this reaction, as iodine is a gas ?
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d) What is the role (“job”) of lithium ions in this reaction ?
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e) Write an ionic equation for this reaction by removing the “spectator ions”.
f) Which is the more powerful reducing agent in this reaction I atoms or At - ions ? How do you know ?
(a reducing agent reduces the thing that it is reacting with by giving it electrons !)
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Write balanced symbol equations for the following halogen displacement reactions :
g) Bromine and potassium iodide solution ?
____Br2 (aq) + _____ KI (aq)  ____________ (aq) + _____________ (aq)
h) Fluorine and sodium chloride solution ?
i) Bromine and potassium astatide solution ?
Write ionic equations for the three reactions above (g – i_).
j) Bromine and potassium iodide solution ?
k) Fluorine and sodium chloride solution ?
l) Bromine and potassium astatide solution ?
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HW 4a :
Potassium - needed by nerves, plants, and spaceships
Potassium is an essential element for almost all living things and we have around 120 g in our
body, found mainly in red blood cells, muscles, and the brain.
One of its natural isotopes is potassium-40. This is a β-emitter, converting the nucleus to argon-40
explaining why there is 1% of this gas in the Earth's atmosphere.
Potassium in our bodies
Potassium ions have many metabolic functions, the more important of which are regulating
intracellular fluids, solublising proteins, operating nerve impulses, and contracting muscles. The
movement of sodium and potassium across nerve cell membranes allows the transmission of
nerve impulses. This lateral motion of charge passes like a wave along the direction of the fibre,
as if it were an electric current.
Cell membranes have channels through which sodium and potassium ions flow selectively and
against a concentration gradient. There are trillions of these sodium-potassium pumps which can
transfer 200 sodium and potassium ions per second in and out of the cell. Some channels only
permit potassium to pass through.
Toxins and nutrients
The toxin of the black mamba snake kills its victim by blocking the potassium channels. Murders
and executions have been committed by injecting a concentrated solution of potassium chloride
into the blood stream to create an osmotic pressure which prevents the movement of potassium
across the cell membrane. All body functions are affected, but none more dramatically than the
heart muscle, which stops beating.
Potassium is needed in the diet much more than sodium. We require a regular intake because we
have no mechanism for storing this element. Foods rich in potassium include raisins and almonds,
which have 860 mg per 100 g, currants (750), peanuts (680), and bananas (350). There are
important potassium-based food additives such as potassium sodium tartrate (KNaC4H4O6, food
additive E337) which is a component of baking powder and potassium hydrogen sulfite (KHSO 3,
aka E228) which is added to wines to prevent the growth of rogue yeasts.
Potassium salts in the form of potassium nitrate (aka saltpetre,
KNO3), potassium carbonate (aka potash, K2CO3), and potassium
aluminium sulfate (aka alum, KAl(SO4)2) have been known for
centuries. In the 1600s it was known that potash was a way of
improving soil. Today potassium chloride is widely used as a
fertilizer and called by its traditional name of MoP, or muriate of
potash.
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The past and the present
On 6 October 1807, Humphry Davy (1778-1829) placed some moist potash on a platinum disc
connected to the negative pole of his battery. He put a platinum wire, connected to the positive
pole, in contact with the potash and soon observed the formation of metallic globules on the
platinum disc. This was the first time a metal had been isolated using electrolysis. He named the
new metal potassium, and noted that when dropped in water it formed globules which skimmed
about on the surface, burning with a lavender-coloured flame.
World production of potassium ores like sylvite (KCl) and carnallite (KMgCl3.6H2O) totals about 35
million tonnes. The UK extracts about 400 000 tonnes of KCl a year from a mine at Boulby in
Yorkshire. Most ends up as fertilizer, but some is used to make potassium hydroxide (KOH), by
the electrolysis of KCl solution. This is used to make liquid soaps and detergents, or is converted
to potassium carbonate (K2CO3) for glass manufacture. A little ends up in pharmaceuticals,
medical drips, and saline injections.
Of potassium metal itself, about 200 tonnes per year are produced by passing sodium vapour up a
column at 870°C down which molten potassium chloride flows. They react and release potassium
vapour which is condensed at the top. Potassium metal is produced to manufacture potassium
superoxide (KO2) which is formed when it burns in oxygen gas. This is kept in mines,
submarines and space vehicles to regenerate the oxygen in the air when it has become depleted.
This oxide reacts with carbon dioxide to form potassium carbonate (K 2CO3) and in so doing it
releases oxygen gas.
Fact file
Atomic number 19; atomic mass 39.0983; melting point 64°C (an alloy with caesium and sodium
remains liquid down to -78°C), boiling point 774°C, density: 0.86 g cm-3. Potassium is a soft,
silvery, highly reactive alkali metal. Its preferred state is the K + ion. The metal itself dissolves in
liquid ammonia to form a blue solution which is a powerful reducing agent.
Questions:
1] Potassium is a highly reactive metal element and yet 120g of potassium are needed in the
human body. How is this possible ?
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2] What is potassium used for in the human body ?
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3] Why is snake venom so dangerous to the human body ?
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4] What sources of potassium are there in our diet and which is the most significant ?
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5] What other uses are there for potassium ?
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HW 4b : atom versus ion (Group 1)
During the reaction of potassium with water a potassium atom forms a potassium ion.
Compare a potassium atom with a potassium ion in terms of:
● electronic configurations
● an explanation of how a potassium atom forms a potassium ion
● relative “stability” of the atom and the ion (include an explanation).
This is an extended answer “compare” question worth up to 6 marks
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Mark : ______ /6
Feedback:
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Marked by:_______________
HW 4c : Group 1 equations
Elements have 1 electron in outer shell
Always form 1+ ions
Elements always oxidised (OIL) X  X+ + e
Reactions vigorous and more violent as you go down group
1] Group 1 + Oxygen
a) balance this
______Li + _______O2  ________Li2O
b) write a half-equation to show what happened to lithium during this reaction.
c) write a symbol equation for the reaction of rubidium with oxygen .
2] Group 1 + water
a) Explain why group 1 are known as the “alkali metals” ?
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b) Why do group 1 metals react with water ?
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c) Balance this :
______Cs (s) + _______H2O (l)  _____CsOH (aq) + _____ H2 (g)
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d) write a half-equation to show what happened to Caesium in the above equation.
e) write a balanced symbol equation for the reaction of rubidium with water.
f) In Q2c, which ion in the solution causes it to be alkaline ?
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3] Group 1 + Group 7
a) In terms of electrons, how do group 1 and group 7 elements change when they react together ?
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b) What is the formula of the compound Sodium iodide ?
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c) Complete this symbol equation for the reaction of potassium with chlorine (incl. state symbols) & balance
it.
_____ K (s) + ______Cl2 (l)  ______________
(
)
d) Use your work on 3c to write a balanced symbol equation for the reaction of rubidium with astatine.
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HW 5a:
Explaining the decreasing reactivity of the halogens.
When a solution of bromine is added to potassium iodide solution, there is a distinctive colour
change from orangey-yellow to a transparent purple. This indicates that a chemical reaction has
happened.
A solvent called hexane is added to the same tube and shaken. Like oil, hexane does not mix with
water. Two layers form. The bottom water layer is now a very feint purple colour and the top layer
is a dark, vibrant purple colour.
Explain why the chemical reaction happened, using ideas about the nucleus and electrons. You
may wish to include a symbol equation in your answer. Include in your answer a brief explanation
of the second part of the experiment. [6]
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Mark : ______ /6
Feedback:
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Marked by:_______________
HW 5b:
Group 1 explaining what happens
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