3.7/3.8 Periodicity (Spec) Flashcards
Element arrangement in Periodic Table
Increasing atomic number
Groups (columns) w/ elements w/ same # of outer-shell electrons, in the same orbital. Similar properties
Periods (rows) w/ same # of electron shells
Periodicity
Repeating pattern in properties at regular intervals
Nth ionisation energy
Energy required to remove 1 mole of electrons from 1 mole of (n-1) charged particles to form 1 mole of n+ charged particles
Trend of successive ionisation energies
Increase for an element:
Increasing electrostatic attraction on each electron from nucleus
Decreasing electron shielding & atomic radius - electron shells removed
Large increase in ionisation energy indicates new main energy level
Trend down group in first ionisation energy
Decreases overall:
Nuclear charge increases
Increase in electron shielding and atomic radius outweighs
Trend across period in first ionisation energy
Increases overall:
Nuclear charge increases
Similar level of electron shielding, decreasing atomic radius increases effective electrostatic attraction of outer electrons by nucleus
Metallic bonding
Strong electrostatic attraction between positive metal ions and a sea of delocalised electrons
Melting point trend (Period 2&3)
Increases from Group 1-14, there is a sharp decrease between Group 14 & 15, and melting points are comparatively low in Groups 15-18.
Reactions of Group 2 metals with oxygen gas
Group 2 metal + oxygen gas -> Group 2 oxide
Reactions of Group 2 metals with water
Group 2 metal + water -> Group 2 hydroxide + hydrogen gas
Reactions of Group 2 metals with dilute acid
Group 2 metal + dilute acid -> salt + hydrogen
Trend in reactivity down group 2
Reactivity increases because ionisation energies decrease because of decreasing attraction of outer electrons by the nucleus, due to increasing electron shielding and increasing atomic radius
Use of calcium hydroxide
Lower soil acidity
Uses of magnesium hydroxide and calcium carbonate
Regulate stomach acidity - Antacids
Trend in boiling point DOWN Group 7
Increasing due to increasing STRENGTH of London forces, requires increasing quantity of energy to overcome, resulting in a higher boiling point
Trend in state at RTP DOWN Group 7
Darker and more solid
Trend in reactivity DOWN Group 7
Decreasing reactivity, weaker oxidising agents, lower nuclear attraction, more electron shielding due to more inner shells and increasing atomic radius
Disproportionation reaction
Redox reaction where two atoms of the same element are separated so that one is reduced and the other is oxidised
Carbonate test
Dilute nitric acid
Gas bubbled through limewater (aqueous calcium hydroxide)
Negative test - Clear solution
Positive test - Cloudy solution as insoluble calcium carbonate forms
K2CO3 + 2HNO3 -> 2KNO3 + CO2 + H2O
Ca(OH)2 + CO2 -> CaCO3(s) + H2O
Sulfate test
Aqueous barium nitrate
Positive test - White precipitate of barium sulfate
Negative test - Clear solution
Halide test
Aqueous silver nitrate
Positive test: White precipitate of silver chloride
Cream precipitate of silver bromide
Yellow precipitate of silver iodide
Add aqueous ammonia:
Dilute: Silver chloride dissolves
Concentrated: Silver bromide dissolves
Concentrated: Silver iodide does not dissolve
Ammonium test
Aqueous NaOH Heat Moist litmus Positive test - Blue Negative test - Red