Chapter 7-8 - Periodicity&Reactivity Trends Flashcards
The repeating…
Define Periodicity
The repeating pattern of trends in physical and chemical properties which occurs across different periods in the periodic table.
nuclear attraction? ionisation energy?
Trends across a period
Nuclear charge - Increases
Shielding - Stays roughly the same
Atomic Radius - Decreases
= Nuclear Attraction - Increases
= Ionisation energy increases
Trends down a group
Nuclear Charge - Increases
Shielding - Increases
Atomic Radius - Increases
= Nuclear Attraction decreases because atomic charge and shielding cancel out
= Ionisation energy decreases
= Reactivity increases
The energy required to…
Define First Ionisation Energy
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
Give an equation to represent the First Ionisation Energy
X(g) ——> X+(g) + e-
State the factors that affect Ionisation Energy
Nuclear Charge
Atomic Radius
Electron Shielding
when an element is…
Define Disproportionation
When an element is simultaneously oxidised and reduced to form 2 different products
Metal + Oxygen
= Metal Oxide
Metal + Water
= Metal Hydroxide + Hydrogen
Metal Oxide + Water
= Metal Hydroxide
Metal + Acid
= Salt + Hydrogen
What compound can be used to neutralise acids soils?
Calcium Hydroxide
Which 2 compounds can be used to treat indigestion?
Magnesium Hydroxide and Calcium Carbonate
2 facts about of Chlorine
Kills Bacteria and is toxic
Colour of fluorine as an element
Pale Yellow Gas
Colour of Chlorine as an element
Pale Green Gas
Colour of Chlorine in water
Pale Green
Colour of Chlorine in hexane (an organic solvent)
Pale Green
Colour of Bromine as an element
Red-Brown Liquid
Colour of Bromine in water
Orange (yellow-orange)
Colour of Bromine in hexane (an organic solvent)
Orange (orange-red)
Colour of Iodine as an element
Grey Crystals (purple vapour)
Colour of Iodine in water
Brown
Colour of Iodine in hexane (an organic solvent)
Violet
Why do the boiling points increase down group 7?
Due to the increased london forces between molecules that require more kinetic energy to overcome
Why does reactivity decrease down group 7?
It becomes harder to gain electrons to form 1- ions.
Cl2 + H2O
= HClO + HCl
Chlorine + cold, dilute, aqueous sodium hydroxide
= NaClO (bleach) + NaCl + Water
State the 3 steps to test for Halide ions
- add dilute nitric acid
- add silver nitrate solution
- add ammonium solution
Chloride positive result
White precipate formed
soluble in all conc. ammonia
Bromide positive result
Cream precipitate formed
soluble only in concentrated ammonia
Iodide positive result
Yellow precipitate formed
Insoluble in ammonia
Test for carbonate ions
- add dilute acid
- bubble through limewater
PR- turns cloudy (CO2 formed)
Test for sulphate ions
- add dilute HCl
- add barium chloride sol.
PR- white precipitate forms (barium sulphate)
Test for Ammonium ions
- add sodium hydroxide
- warm gently
PR- ammonia gas turns red litmus paper blue
Cl2 + NaOH (aq)
chlorine + cold, dilute sodium hydroxide
NaClO + NaCl + H2O
bleach + sodium chloride + water
when asked about boiling points talk about…
- london forces etc..
when asked about reactivity talk about…
- shells/ electrons
Br2 + Cl- ion
no reaction as Chlorine is more reactive than Bromine so solution remains orange in cyclohexane
halogen reactivity
Cl2 > Br2 > I2
displacement reaction to confirm order of halogen reactivity
addition of Br2 (aq) to I- (aq) ions
