IGCSE Chemistry Flashcards
Step 6 of extracting iron from bauxite (2)
molten slag removed - used for cement + roads
pure iron obtained
Step 5 of extracting iron from bauxite (4)
Limestone added to remove impurities
impurities react with limestone to produce molten slag
CaCO3 –> CaO + CO2
CaO + SiO2 –> CaSiO3 (slag)
Step 4 of extracting iron from haematite (2)
carbon reduces iron ore in hottest part of furnace
Fe2O3 (s) + 3C(s) –> 2FE(l) + 3CO (g)
Step 3 of extracting iron from bauxite (2)
carbon monoxide reduces iron oxide to iron by combining with oxygen in iron oxide
Fe2O3 + 3CO –> 2Fe + 3CO2
Step 2 of Extracting iron from haematite (2)
carbon monoxide produced in reduction reaction between carbon + carbon dioxide due to high temp.
CO2 + C –> 2CO
Step 1 of extracting Iron from haematite (3)
carbon combines with oxygen to from carbon dioxide in exothermic reaction
causes high temperature in furnace
C + O2 –> CO2
Main iron ore
Haematite
Extracting metals with heat and carbon (2)
slightly more reactive metals
ore dropped into fire –> heat + carbon caused metal to displace from compound –> carbon joins with oxygen
Extracting metals by heat
least reactive metals can be extracted using just heat
Define ore
naturally occuring metal compounds (usually with oxygen)
Reactivity Series (13)
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold
Copper reaction with water
no reaction
Magnesium reaction with water
reacts slowly with cold water
Calcium reaction with water
bubbles of gas immediately form
Alkali metal word equation with water
Alkali metal + water –> alkali metal hydroxide + hydrogen
Reaction of Potassium with water (2)
lilac flame produced
hydrogen gas produced
Reaction of Sodium with water (2)
fizzes around water
gives off hydrogen gas
Structure of Alloys (2)
alloys have different sized atoms
prevents layers sliding over each other –> stronger + less flexible
Reaction of Lithium with water
bubbles of hydrogen gas given off
Solder Alloy (2)
Tin + Lead
Lower melting point
Stainless Steel (2)
Iron + Carbon + Chromium + Nickel
resistant to corrosion
Cupronickel (2)
Copper + Nickel
cheaper than silver –> used for coins
Bronze Alloy (2)
Copper + Tin
Hard
Brass Alloy (2)
Copper + Zinc
Easier to shape
Hard Steel/High Carbon Steel Alloy (2)
Iron + 2.5% of carbon
hard
Mild Steel Alloy (2)
Iron + 0.25% of Carbon
can be easily shaped
Why are metals malleable and ductile (3)
metallic bonds not as strong
so layers of ions able to slide over each other
ions can move into different positions when hammered
Define metallic bonding (3)
metal atoms will give up their electrons to form cations
free electrons form “sea” + surround cations –> positive + negative attract holding bond together
strong attraction between closely packed cations and a “sea” of delocalised electrons
Properties of transition metals (6)
most have high density
high melting points
not very reactive
forms coloured compounds
used as catalysts
more than 1 valence electron
Properties of noble gases (2)
inert/unreactive
monoatomic
Define displacement
more reactive element takes less reactive element’s place
Halogen properties (4)
diatomic
colour becomes darker as you go down group
density increases as you go down group
melting point increases as you go down group
Colour of iodine solution (reaction with water)
yellow/brown
Colour of bromine solution (reaction with water)
orange
Colour of chlorine solution (reaction with water)
pale yellow
Halogen colours (4)
fluorine - pale-yellow gas
chlorine - pale-green gas
bromine - red-brown liquid
iodine - black, shiny solid
How alkali metals react with water (4)
react vigorously
produce effervescence
float on surface, moving rapidly
make water alkaline
Alkali metal reaction with halogen
metal + halogen –> metal halogen(ide)
Alkali metal reaction with water
alkali metal + water –> metal hydroxide + hydrogen
Alkali metal reaction with air
metal + oxygen –> metal oxide
colour of potassium flame
lilac
colour of sodium flame
orange/yellow
Colour of lithium flame
red
Density trend of alkali metals
density increases as you go down
Melting point trend of alkali metals
decreases as you go down
Properties of group 1 metals (5)
soft to cut
shiny but react with air quickly
relatively low melting/boiling points
relatively low density
reactive
Volume which a mole of gas occupies in room temperature/pressure
24dm^3
Formula for volume of gas under room pressure/temperature
moles x 24dm^3
Formula for number of moles (2)
mass(g)/Mr (relative atomic mass)
concentration(mol/dm^3) x volume (dm^3)
Avogadro’s constant
6.02 x 10^23 particles
Define a mole (2)
amount of substance
6.02 x 10^23 particles
Why non-metals less reactive as they go down a group (4)
atom bigger as go down
electrons farther from nucleus
weaker electrostatic force of attraction
harder for atom to accept electrons
What do elements in the same period have the same of
same number of electron shells
Properties of non-metals (5)
smaller atomic radius
no conduction
low melting/boiling point
brittle
dull
Properties of metals (6)
large atomic radius
conduct heat/electricity
shiny
malleable
shiny
high melting/boiling point
Define metalloids
elements with characteristics of metals and non-metals
Why metals become more reactive going down a group (4)
atom bigger as go down
electrons farther from nucleus
electrostatic force of attraction weaker
easier for valence electron to be removed
Define groups in a periodic table
vertical columns
Periods in a periodic table
horizontal row
Define periodicity
trends in periodic table
Why do giant covalent bonds have high melting and boiling points (2)
every strong covalent bond must be broken
hence require lots of energy
Structure of giant covalent structures (2)
have strong covalent bonds - no weak
Melting and boiling points of giant covalent structures
high melting and boiling points
Are covalent substances insoluble or soluble in water
insoluble
Do covalent substances conduct electricity why? (3)
do not conduct electricity as no free electrons to carry charge
do not have ions
exceptions - some covalent substances will form ions when dissolved in water
What are covalent bonds said to be
volatile since they have low melting and boiling points
Define volatility
how easily substances vaporise
Why do covalent bonds have low melting and boiling points (2)
covalent bonds (intramolecular forces) not broken when substance melted or boiled
much weaker forces of attraction (intermolecular forces) broken
Melting and boiling point of covalent bonds
low melting and boiling points
Number of covalent bonds for silicon (IV) oxide
4
Examples of macromolecules (3)
silicon (IV) oxide
diamond
graphite
Why is graphite able to conduct electricity (2)
has delocalised electrons (electron left from not having 4th bond)
electron is free to move and allows conduction
Can graphite conduct electricity
yes
Can diamond conduct electricity
no
Properties of graphite (4)
strong bonds between atoms
weak intermolecular forces between layers - layers can slide over each other
flaky and can be used as lubricant
conducts electricity
Properties of diamond (3)
strong covalent bonds
high melting point - lots of energy needed to break strong bonds between atoms
hard substance
Graphite structure (3)
carbon atoms in hexagonal shape in layers
each carbon atom bonds to 3 other carbon atoms
layers held together by weak intermolecular forces of attraction
Diamond structure (3)
carbon atoms arranged in tetrahedral structure
carbon bonded to 4 other carbon atoms
held together by strong covalent bonds
2 giant covalent structures of carbon
diamond
graphite
Define allotropes
different forms of same element
Define macromolecules
molecules that contain large number of atoms
How is a covalent bond held together (3)
positively charged protons in the nucleus
negatively charged electrons in shared area
electrons and protons attracted as opposites attract
Group 8 valency
0
Group 7 valency
1
Group 6 valency
2
Group 5 valency
3
Group 4 valency
4
Group 3 valency
3
Group 2 valency
2
Group 1 valency
1
Define valency
number of bonds an element needs to form
Example of triatomic molecule
H2O
Define triatomic molecule
molecule made up of 3 atoms bonded together
Define a diatomic molecule
molecule made up of 2 atoms bonded together
Define a covalent bond
pair of electrons shared by two atoms
When will a covalent bond form with
non-metals
What determines strength of ionic bond
greater charge greater strength
Features of ionic substances (5)
hard crystals - strong attraction between positive and negative ions
high melting points - lot of energy needed to overcome forces of attraction between ions
dissolves in water - water forms electrostatic attractions with ions and “pluck” them off lattice
does not conduct when solid - electrons held tightly in lattice and cannot move
conducts when molten/solution - lattice breaks and ions free to move
Can non-metals and covalent substances (except graphite) conduct electricity
no
At which states do metals conduct (2)
solid
liquid
Define an electrolyte
molten substance or solution that conducts
In metals and graphite which part of the atom moves and carries an electric current
outer electrons of atoms (delocalised electrons) which can move and carry current
Define electricity
flow of charged particles (ions or electrons)
Define reduction
when an atom/ion gains electrons
Define oxidation
when an atom/ion loses electrons
Ionic lattice structure
ion surrounded by ions of opposite charge
Name given to pattern which ionic compounds are organised in
ionic lattice
Define an ionic bond
electrostatic force of attraction between oppositely charged ions
How do ions form (3)
metal atoms give electrons to non-metal atoms
both atoms are stable charged particles
atoms attracted as they are oppositely charged
Which substances will an ionic bond form between (2)
metal
non-metal
Define anions
negative ions
Define cations
positive ions
What is the charge of an atom which has gained electrons
negative charge
Which atoms tend to lose electrons
metals
What is the charge of an atom which has lost electrons
positive charge
Properties of Isotopes
have same chemical properties as they have same number of valence electrons
Define an isotope
atoms of same element with same atomic number but different mass number due to different neutron number
What happens to the number of electrons as we move along a period
number of electrons in outer shell increases
What do elements in the same group have and why (2)
similar chemical properties
due to same number of valence electrons
Name of outer electrons
valence electrons
Features of noble gases (2)
full outer electron shell
are stable as electron shell full
How are electrons arranged (4)
arranged in shells
first shell holds 2 electrons
2nd shell holds 8 electrons
3rd shell holds 8 electrons
What is most of an atom
empty space
What does nucleon/mass number show
number of protons and neutrons an atom has
Define periodicity
trend that can be seen in periodic table
What happens to proton/atomic number when you move from left to right across a period
proton/atomic number increases
What does proton/atomic number show
number of protons an atom has
What does nuclide notation show (3)
element symbol
proton/atomic number
nucleon (mass) number
What is the charge of atoms (2)
atoms have no charge (neutral)
number of protons equal to number of electrons
Features of neutrons (3)
found in nucleus of atom
have no charge and are neutral (0)
have relative mass of 1 amu
Features of electrons (3)
found in electron shells orbiting nucleus
have negative charge (-1)
have relative mass of 1/2000
Features of protons (3)
found in nucleus
have a positive charge (+1)
have relative mass of 1 atomic mass unit (amu)
Name of centre of atom
nucleus
What 3 sub-atomic particles are in an atom (3)
proton
neutron
electron
Define concentration of a solution (2)
amount of solute dissolved in certain volume
can be expressed as number of moles of solute in one decimetre cubed of solution
Define solvent
substance which does the dissolving
Define solute
substance that is dissolved
Define a solution
mixture formed when one substance dissolves fully into another
Examples of alloys (3)
steel
bronze
brass
Define alloys
substances formed when metals mix with other elements
Define metalloids
elements that exhibit characters of both non-metals and metals
Exceptions to metal and non-metal properties (4)
carbon/silicon = high melting points
carbon conducts electricityas graphite
mercury = low melting point
alkali metals = soft, have low melting points, not sonorous
Properties of metals (7)
shiny/lustrous
good conductors (heat and electricity)
high melting and boiling points
high tensile strength
sonorous (rings when struck)
ductile (can be stretched into wire)
malleable (can be beaten into shape)
Define mixture
contains elements and compounds not chemically joined together
Chemical equation of Hydrated cobalt(II) chloride <-> Anhydrous cobalt(II) chloride + Water
CoCl2 6H2O(s) -> CoCl2(s) + 6H2O(l)
Word equation of Hydrated copper(II) sulfate crystals <-> Anhydrous copper(II) sulfate + Water
CuSO4 5H2O(s) -> CuSO4(s) + 5H2O(l)
Define an element
a substance which contains only one type of atom
Colour change from hydrated cobalt chloride crystals to anhydrous cobalt chloride
pink crystals to blue
Colour change from hydrated copper sulfate crystals to anhydrous copper sulfate
blue crystals to white powder
Name reversible reactions (2)
Hydrated copper(II) sulfate crystals <-> Anhydrous copper(II) sulfate + Water
Hydrated cobalt(II) chloride <-> Anhydrous cobalt(II) chloride + Water
Name indicators of chemical reaction (4)
colour change
gas produced
solid formed
temperature change
Define a physical change (3)
involve a change of state
no new substance is made
easily reversible
Define a chemical reaction (2)
reaction which occurs when 2 or more substances react to form a new substance
difficult to reverse/irreversible
Determinants of rate of diffusion (2)
molecular mass - larger molecular mass is slower
vacuum - faster as no other particles to collide with