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What is reduction?
gain of electrons
What is oxidation?
loss of electrons
What is an oxidation number?
the number of electrons an atom uses to bond with any other atom
What is the oxidation number of an uncombined element (e.g. O₂)?
0
What is the oxidation number if combined oxygen (e.g. H₂O)?
-2
What are the exceptions to the oxidation number of oxygen?
-1 (peroxides, H₂O₂ / compounds with fluorine)
What is the oxidation number of hydrogen (e.g. H₂O)?
+1
What is the oxidation number of hydrogen in metal hydrides (e.g. LiH)?
1-
What is the oxidation number of a monoatomic ion?
equal to the ionic charge
How do oxidation numbers work in polyatomic ions?
the sum of the individual oxidation numbers add up to the charge on the ion
What is the oxidation number of fluorine?
-1
What is disproportionation?
reaction in which both oxidation and reduction take place
What is the oxidation number of a metal?
0 (uncombined element)
What is periodicity?
repeating trends in chemical and physical properties
What is first ionisation energy?
energy required to remove one mole of electrons from one mole of gaseous atoms to forms one mole of gaseous 1+ ions
What is the equation for the first ionisation energy of magnesium?
Mg₍₉₎ → Mg⁺₍₉₎ + e⁻
What are the factors that affect ionisation energy?
atomic radius
nuclear charge
electron shielding
How does ionisation energy change across a period?
general increase
Why does ionisation energy change across a period?
increase in nuclear charge
decrease in atomic radius
more energy needed to remove one electron
What are the exceptions in ionisation energy change in period 3?
aluminium, sulphur
Why doesn’t aluminium follow the typical patterns in ionisation energy across period three(3)?
outer electron in 3p orbital is higher than the 3s electron
Why doesn’t sulphur follow the typical patterns in ionisation energy across period three(3)?
repulsion between the two electrons in the last 3p orbital
Why does first ionisation energy decrease between group two(2) and group three(3)?
in group 3, the outermost electrons are in p orbitals, which are easier to remove than in s orbitals
Does first ionisation energy increase or decrease between the end of one period and the start of another?
decrease
Why does first ionisation energy decrease between the end of one period and the start of another?
increased atomic radius
increased shielding
Why does first ionisation energy decrease from group 5 to group 6?
group 5 electrons are single, group 6 are paired. due to repulsion group 6 electrons are easier to remove
Does first ionisation energy increase or decrease down group 2?
decrease
Why does first ionisation energy decrease down group 2?
increased atomic radius
increased shielding
What are the properties of giant metallic lattices?
high melting/boiling points
good electrical conductors
malleable
ductile
What is the structure of lithium and beryllium?
giant metallic
Describe the forces in lithium and beryllium.
strong attraction between ions and delocalised electrons
What is the type of bonding in lithium and beryllium?
metallic bonding
What is the structure of boron and carbon?
giant covalent
What is the structure of nitrogen, oxgyen, fluorine and neon?
simple molecular
Describe the forces in boron and carbon.
strong bonds between atoms
What are the forces in nitrogen, oxygen, fluorine, and neon?
weak intermolecular forces
What is the type of bonding in boron and carbon?
covalent
What is the type of bonding in nitrogen, oxygen, fluorine, and neon?
covalent
What is the structure of sodium, magnesium, and aluminium?
giant metallic
What is the stucture of silicon?
giant covalent
What is the structure of phosphorus, sulphur, chlorine, and argon?
simple molecular
What is a common name given to group 2 metals?
alkaline earth metals
What are the properties of group 2 metals?
high melting/boiling points
low density metals
white solid compounds
The highest energy electrons of group 2 metals are in which subshell?
s subshell
Does reactivity increase or decrease down group 2?
increase
Why does reactivity increase down group 2?
increased atomic radius
increased shielding
What happens to first ionisation energy as you go down group 2?
decreases
Why does ionisation enegy decrease down group 2?
more electron shells = more shielding
increase in atomic radius = weaker force between outermost electron and nucleus
How do calcium and oxygen react?
2Ca₍ₛ₎ + O₂₍₉₎ → 2CaO₍ₛ₎
group 2 metal + water → ?
metal hydroxide + hydrogen gas
Which group 2 metal does not react with water?
beryllium
Why doesn’t beryllium react with water?
high ionisation energy
small size
Which group 2 metal reacts slowly with water?
magnesium
What is the equation for Barium reacting with water?
Ba₍ₛ₎ + 2H₂O₍ₗ₎ → Ba(OH)₂₍ₐq₎ + H₂₍₉₎
group 2 metal + dilute acid → ?
metal salt + hydrogen gas
What is the equation for the reaction of calcium and HCl?
Ca₍ₛ₎ + 2HCl₍ₐq₎ → CaCl₂₍ₛ₎ + H₂₍₉₎
What is the equation when a group two(2) oxide reacts with water?
MO₍ₛ₎ + H₂O₍ₗ₎ → M(OH)₂₍ₐq₎
Which group 2 metal is insoluble in water?
beryllium oxide (high hydration energy)
What is the trend in hydroxide solubility down group 2?
increases down the group
What is calcium hydroxide (Ca(OH)₂) used for?
neutralising soil
What is magnesium hydroxide (Mg(OH)₂) used for?
treat indigestion and heartburn
What is calcium carbonate (CaCO₃) used for?
present in chalk, limestone and marble / used in building construction
What is the drawback of using calcium carbonate (CaCO₃) in construction?
reacts with acid
What is the trend in boiling point down group 7?
increases
Why does boiling point increase down group 7?
more electrons = stronger london forces = more energy required to overcome
What is the trend in reactivity down group 7?
decreases
Why does reactivity decrease down group 7?
increased atomic radius
increased shielding
decreased ability to gain an electron
What is the trend in oxidising ability down group 7?
decreases
Why does oxidising ability decrease down group 7?
increase in shielding means it is harder to gain an electron and be reduced
What is the trend in reducing ability of halides down group 7?
increases
Why does the reducing ability of the halides increase down group 7?
I⁻ has the most occupied electron shell so the weakest force of attraction to outer electrons and so it is easiest to be oxidised and lose electrons
What colour is Cl⁻ in water?
pale green
What colour is Br⁻ in water?
orange
What colour is I⁻ in water?
brown
What colour is Cl⁻ in cyclohexane?
pale green
What colour is Br⁻ in cyclohexane?
orange
What colour is I⁻ in cyclohexane?
violet, purple, pink
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