Module 3 Flashcards
Periodic Table & Energy (21 cards)
1st Ionisation Energy
The energy required to remove an electron from each atom in a mole of gaseous atoms
Trend in 1st I.E. across periods
Left –> Right
Nuclear charge increases, so atomic radius decreases (outer electrons pulled closer to nucleus)
Stronger nuclear attraction
Increasing 1st I.E.
Trend in 1st I.E. down groups
More electron shells, so outer electrons further from nucleus and stronger shielding effect
Weaker nuclear attraction
Easier to remove outer electron
Decreasing
Metallic Bonding, Structure and Properties
Strong electrostatic attraction between cations and delocalised electrons (high melting point, good electrical conductor) forming a giant metallic lattice
Insoluble
Diamond - Bonding, Structure and Properties
Giant covalent lattice
Strong covalent bonds between carbon atoms (high melting point, hard) no delocalised electrons (poor electrical conductor)
Insoluble
Graphite - Bonding, Structure and Properties
Giant covalent lattice
Strong covalent bonds between carbon atoms (high melting point) 1 delocalised electron per carbon (electrical conductor) weak IDDs between layers (slippery / lubricant)
Insoluble
Graphene - Bonding, Structure and Properties
Single layer of graphite - giant covalent lattice, strong covalent bonds between carbon atoms (high MP) delocalised electrons (conducts electricity)
Insoluble
Silicon - Bonding, Structure and Properties
Network of atoms joined by covalent bonds, no delocalised electrons (poor electrical conductor) giant lattice (high MP)
Insoluble
Ionic Bonding
Strong electrostatic attraction between oppositely charged ions in all directions - giant ionic lattice (high MP, soluble) ions held in place when solid, mobile when molten (only conducts electricity when molten)
Variation in melting points across periods
Increases up to group 3 (metallic with more delocalised electrons) Highest at group 4 (giant covalent lattices of C or Si) then very low for remaining groups (simple covalent molecules)
Gp2 metal + oxygen
2X + O2 –> 2XO
Gp2 metal + water
X + 2H2O –> X(OH)2 + H2
Gp2 metal + acid
X + 2HCl –> XCl2 + H2
Trend in reactivity (group 2)
Increases down group
More shells of electrons - outer electrons further from nucleus + greater shielding effect
Weaker nuclear attraction
Lower ionisation energy - easier to remove outer electrons
Gp2 oxide + H2O
XO + H2O –> X(OH)2
Uses of Gp2 compounds
Calcium hydroxide used in agriculture to neutralise acidic soils
Magnesium hydroxide / calcium carbonate used as antacids to treat indigestion
Trend in reactivity of halogens
Decreasing down group
Outer electron shell further from nucleus and greater electron shielding - weaker nuclear attraction
Harder to accept electrons from other atoms
Disproportionation
Oxidation and reduction of the same element
Examples of disproportionation
Use of chlorine in water treatment
Chlorine + sodium hydroxide to form bleach and sodium chloride
Benefits and risks of chlorine use in water treatment
Kills bacteria
Toxic
Test for halide ions
Add silver nitrate to the sample, produces a white / cream / yellow precipitate
