Flashcards
Chemistry Unit 3
Cards in this deck (81)
- 1In the early version of the periodic table (by Newlands and then Mendeleev), how were the elements arranged?In the early version of the
periodic table (by Newlands
and then Mendeleev), the
elements were arranged by
atomic weight. - 2What can we say about the elements in the same group of the periodic table?Elements in the same group of
the periodic table have similar
chemical and physical
properties. - 3Why is the periodic table called the “periodic” table?The periodic table is called the
“periodic” table because
elements with similar
properties occur at regular
intervals. - 4What was the problem with the early periodic table, where elements were arranged in order of atomic weight?In the early periodic table, where
elements were arranged in order
of atomic weight, some elements
were clearly in the wrong group
(based on their properties). - 5When Mendeleev proposed his early periodic table, what problem did he highlight?When Mendeleev proposed
his early periodic table, he
realised that some elements
had not been discovered. - 6How did Mendeleev adjust his periodic table to take into account the problems he identified?Mendeleev sometimes switched the
order of the elements if they were
clearly in the wrong group. He also
left gaps for elements which he
realised had not been discovered. - 7How are the elements arranged in the modern periodic table?In the modern periodic table,
elements are arranged in order
of atomic (proton) number.
Now, all the elements were in
the appropriate groups. - 8Which group was not featured on the early periodic table?Group 0 was not featured on
the early periodic table as the
group 0 (noble gases) had not
been discovered - 9What can we say about the electronic structure of elements in the same group of the periodic table?Elements in the same group of
the periodic table have the same
number of electrons in their outer
energy level (apart from group 0,
where helium has 2 and the rest
have 8). - 10What do we call the elements in group 1 of the periodic table?Elements in group 1 of the
periodic table are called the
alkali metals. - 11What can we say about the density of the elements in group 1 (the alkali metals)?All of the elements in group 1
(alkali metals) are metals with
low density (Li, Na, K are less
dense than water). - 12How do group 1 (alkali metals) react with non-metals?Group 1 (alkali metals) react with nonmetals
to form ionic compounds. The
alkali metal ion has a charge of +1.
The compounds produced are white
solids that dissolve in water, forming
colourless solutions. - 13How do group 1 (alkali) metals react with water?Group 1 (alkali) metals react with
water releasing hydrogen. They
form hydroxides which dissolve in
water, forming an alkaline solution. - 14What happens as we move down group 1, in terms of: • reactivity of the elements • melting and boiling pointsAs we move down group 1,
• The elements get more reactive
• The melting and boiling points
decrease - 15What can we say about transition metals compared to the metals in group 1.Compared to group 1 metals, transition metals:
• Are denser
• Have higher melting points (apart from
mercury)
• Are stronger and harder
• Are much less reactive
• Do not react as vigorously with water and oxygen - 16State three facts about transition metals.Many transition metals
• Can have ions with different charges
• Form coloured compounds
• Are useful as catalysts - 17What do we call the elements in group 7?Elements in group 7 are called
the halogens. - 18How do the halogens react with metals?Halogens react with metals to
form ionic compounds. The
halogen ion (now called a halide)
has a charge of -1. - 19What happens as we move down group 7, in terms of: • reactivity of the elements • melting and boiling pointsAs we move down group 7,
• the elements get less reactive
• the melting and boiling points
increase - 20Complete this sentence: A more reactive halogen can …………….. a less reactive halogen from an aqueous solution of its saltA more reactive halogen can
displace a less reactive halogen
from an aqueous solution of its salt - 21What happens in the following reaction? chlorine + lithium bromide ->chlorine + lithium bromide
-> bromine + lithium chloride
Chlorine is more reactive than bromine so
it displaced the bromine from the lithium
bromide. - 22What happens in the following reaction? chlorine + lithium fluoride ->chlorine + lithium fluoride
-> chlorine + lithium fluoride
Chlorine is less reactive than fluorine so it
cannot displace the fluorine from the
lithium fluoride. - 23Explain why group 1 (alkali) metals become more reactive as we move down the group.Group 1 (alkali) metals get more reactive
as we move down the group because the
outer electron is more easily lost.
• The outer electron is further from the
nucleus.
• Internal energy levels shield the outer
electron from the nucleus. - 24Explain why group 7 elements (halogens) become less reactive as we move down the group.Group 7 elements (halogens) get less reactive as we move down the group because an electron is less easily gained into the outer energy level.
• The outer electron is further from the
nucleus.
• Internal energy levels shield the outer
electron from the nucleus. - 25How can we determine the hardness of a sample of water?Hard water forms a scum (rather than
a lather) with soap so if a sample of
water is very hard, it will need more
soap to form a lather. The amount of
soap needed to form a lather indicates
the hardness of the water. - 26How do soapless detergents react with hard water?Soapless detergents do not
form a scum with hard water.
They form a lather. - 27What makes hard water hard?Hard water is hard because it
contains dissolved compounds
of calcium or magnesium. - 28How is hard water formed?When water flows over rocks
containing calcium or
magnesium compounds, these
can dissolve in the water,
making it hard. - 29What is meant by temporary hard water?Temporary hard water contains
hydrogencarbonate ions (HCO3-). If we boil this water, these form carbonate ions. The carbonate ions react with the calcium ions / magnesium ions, forming a precipitate. This removes the calcium ions / magnesium ions from solution which makes the water soft. - 30How can we tell the difference between permanent hard water and temporary hard water?If we boil temporary hard
water, it becomes soft.
However, boiling permanent
hard water has no effect on the
hardness. - 31How can hard water cost us money?Hard water requires more soap to
develop a lather. Also when temporary
hard water is heated it forms scale
(precipitate of calcium carbonate or
magnesium carbonate). Scale reduces
the efficiency of heating systems and
kettles. - 32What are the benefits of hard water?Hard water can contain calcium
ions. These help us to develop
strong bones and teeth. Calcium
ions can also decrease the risk
of heart disease. - 33How can we soften hard water using sodium carbonate?If we add sodium carbonate to hard
water, the carbonate ions react with
the calcium ions /magnesium ions.
This forms a precipitate, removing
these ions from solution. This
makes the water soft. - 34How can we soften water using a water softener?Water softeners carry out “ion-exchange”.
They contain either hydrogen ions or
sodium ions. When hard water passes
through, the calcium ions / magnesium
ions in the water are switched for the
hydrogen ions / sodium ions, making the
water soft. - 35State the three stages of preparing drinking water.• Select a source of water e.g.
an unpolluted river.
• Filter out any solids.
• Add chlorine to sterilise the
water (kill microbes). - 36Water filters contain carbon, silver and ion exchange resins. Describe the functions of these.• Carbon removes impurities
such as chlorine.
• Silver kills microbes.
• Ion exchange resins make
hard water soft. - 37Why is fluoride added to drinking water and why do some people object to this?Adding fluoride to drinking water
improves dental health. However,
some people object as it prevents
people from choosing whether they
want to drink water with fluoride. - 38How can completely pure water be produced?Completely pure water can be
produced by distillation.
However, this requires a great
deal of energy and is therefore
extremely expensive. - 39Which equation can we use to determine the amount of heat energy released / taken in during a reaction.Q = m c ΔT
Q = energy (J)
m = mass (g)
c = specific heat capacity (J/g/C)
ΔT = temperature change (C) - 40We can measure the energy released from burning a fuel by using a calorimeter. State two issues with this.1. A great deal of heat energy is
simply passed into the air, rather
than the water in the calorimeter.
2. We should use a metal calorimeter
rather than a glass beaker as
metal is a better conductor of heat
than glass. - 41When we measure the energy change of a chemical reaction, why should we use a polystyrene cup rather than a glass beaker?Polystyrene is a better insulator
than glass. If we used a glass
beaker then heat energy could
pass in or out of the solution,
giving us an incorrect reading. - 42Draw an energy level diagram for an exothermic reaction. Label the activation energyx
- 43Draw an energy level diagram for an endothermic reaction. Label the activation energy.
- 44Describe the bond energy changes that take place during a chemical reaction.Breaking bonds requires
energy (endothermic).
Making bonds releases energy
(exothermic). - 45What can we say about the bond energy changes taking place in an endothermic reaction?In an endothermic reaction,
the energy needed to break
existing bonds is greater than
the energy released from
forming new bonds. - 46What can we say about the bond energy changes taking place in an exothermic reaction?In an exothermic reaction, the
energy released by forming
new bonds is greater than the
energy needed to break
existing bonds. - 47How do catalysts speed up chemical reactions?Catalysts provide a different
pathway for a chemical
reaction with a lower activation
energy. - 48Draw an energy level diagram showing the effect of a catalyst on a chemical reaction.
- 49State the equation for the combustion of hydrogen in engines.hydrogen + oxygen -> water (+energy)
- 50What happens when hydrogen is used in a fuel cell.In a fuel cell, hydrogen reacts
with oxygen to make water.
This also produces electricity.
The electricity can be used to
power a vehicle. - 51State the advantages and disadvantages of using hydrogen in a fuel cell compared to combusting hydrogen in an engine.Hydrogen fuel cells are more efficient
than combusting hydrogen. The water
produced from a hydrogen fuel cell
can be used for drinking water (eg in a
space station). Hydrogen fuel cells
require expensive catalysts. - 52State the flame test results for the following metal ions: • lithium • sodium • potassium • calcium • barium• lithium = crimson
• sodium = yellow
• potassium = lilac
• calcium = red
• barium = green - 53How can we test for calcium and magnesium ions by using sodium hydroxide solution?Both calcium and magnesium
ions will produce a white
precipitate when reacted with
sodium hydroxide solution. - 54How can we test for aluminium ions by using sodium hydroxide solution?Aluminium ions will produce a white
precipitate when reacted with
sodium hydroxide solution. If we
add excess sodium hydroxide
solution, the white precipitate will
redissolve. - 55State the colours of the precipitates formed when the following ions react with sodium hydroxide solution: • copper (II) • iron (II) • iron (III)• copper (II): blue precipitate
• iron (II): green precipitate
• iron (III): brown precipitate - 56How can we test for a metal carbonate (eg sodium carbonate)?First we add any dilute acid.
Bubbles of gas will be produced. If
we pass the gas through limewater
and the limewater turns cloudy, the
gas is carbon dioxide. This tells us
that we had a metal carbonate. - 57How can we test for halide ions? What are the colours of the positive results?We can test for halide ions by adding
silver nitrate solution in the presence
of dilute nitric acid.
• chloride ions = white precipitate
• bromide ions = cream precipitate
• iodide ions = yellow precipitate - 58Describe how we can test for sulfate ions?We can test for sulfate ions by
adding barium chloride solution
in the presence of hydrochloric
acid. Sulfate ions will produce a
white precipitate. - 59Describe how we can use titration to determine the concentration of an acid or alkali.• Fill a burette with the acid
• Use a pipette to measure a known volume of alkali into a conical flask
• Place the conical flask onto a white tile
• Add indicator to the alkali (eg phenolphthalein)
• Gradually add the acid, while swirling the alkali
• Add the acid in drops as you approach the endpoint
• Record the final volume of acid needed - 60State the raw materials for producing ammonia by the Haber process and describe their sources.• Nitrogen is extracted from
the air.
• Hydrogen is extracted from
natural gas (or by
electrolysis of water). - 61State the conditions for producing ammonia by the Haber process.• 200 atmospheres pressure
• 450C
• Iron catalyst
• The ammonia is liquified by cooling
and removed
• Unreacted gases are recycled back
over the catalyst - 62What is meant when a reversible reaction reaches equilibrium?When a reversible reaction
reaches equilibrium, both the
forward and reverse reactions
are taking place at the same
rate. - 63What happens to the yield of an exothermic (reversible) reaction if we increase the temperature?If we increase the temperature
of an exothermic (reversible)
reaction, the yield falls. - 64What happens to the yield of an endothermic (reversible) reaction if we increase the temperature?If we increase the temperature
of an endothermic (reversible)
reaction, the yield increases. - 65What happens to the yield of an exothermic (reversible) reaction if we decrease the temperature?If we decrease the
temperature of an exothermic
(reversible) reaction, the yield
increases. - 66What happens to the yield of an endothermic (reversible) reaction if we decrease the temperature?If we decrease the
temperature of an endothermic
(reversible) reaction, the yield
falls. - 67What happens to a gaseous reversible reaction if we increase the pressure?If we increase the pressure of
a gaseous reversible reaction,
the position of the equilibrium
shifts to the side with the
fewest molecules. - 68Describe how the conditions of the Haber process are a compromise.We can favour the forward reaction by
• Increasing the pressure as there are fewer molecules on the right hand side
• Using a relatively low temperature as the forward reaction is exothermic
• However, a low temperature makes the
reaction rate slow (ie a compromise). Using an iron catalyst increases the rate. - 69State the structural formula of methanol.Methanol has the following
structural formula
CH3OH
- 70State the structural formula of ethanol.Ethanol has the following
structural formula
CH3CH2OH
- 71State the structural formula of propanol.Propanol has the following
structural formula
CH3CH2CH2OH
- 72What is the functional group of the alcohols?The functional group of the
alcohols is OH - 73State three uses of alcohols.Alcohols are used as fuels and
solvents. Ethanol is found in
alcoholic drinks. - 74What happens when alcohols are dissolved in water?When alcohols are dissolved
in water, they form a neutral
solution. - 75What is produced when alcohols are reacted with sodium?When alcohols are reacted
with sodium, hydrogen gas is
produced. - 76Alcohols burn in air. True or false?True: alcohols burn in air.
- 77How can alcohols be oxidised?Alcohols can be oxidised using
chemical oxidising agents or
by bacteria. When alcohols are
oxidised, they form carboxylic
acids. - 78What is vinegar and how is it produced?Vinegar is a dilute solution of
ethanoic acid in water. It is
made by allowing bacteria to
oxidise ethanol. - 79What is the functional group of carboxylic acids?The functional group of
carboxylic acids is
COOH - 80What is the structural formula of methanoic acid?The structural formula of
ethanoic acid is
CH3COOH - 81What is the structural formula of ethanoic acid?The structural formula of
ethanoic acid is
CH3COOH
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- GCSE Chemistry Flashcards on Chemistry Unit 3, created by Rick Wear on 13/04/2017.
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