Unit 1.6 Periodic table

Wherever an element is in the periodic table based on them s, d, p blocks, it means their last electron is within that orbital e.g. silicon is in p block and has 14 electrons therefore arrangement: 1s^2, 2s^2, 2p^6, 3s^2, 3p^2

Na(g) -> Na+(g) + e^-

Each element has an additional proton technically N° of protons increases

Electrons added to the same shell

It goes up?

Increase across a period - Nuclear charge increases - Shielding remains constant Decreases down a group - Effective nuclear charge remains constant - Shielding increases

The ability of an atom within a covalent bond to pull the pair of electrons towards itself

Group 1 & 2: - Decreases down the group due to decreased electrostatic attraction - Atomic radii is greater - Electron more weakly held - Metallic bond is weaker -> Less heat energy to overcome bonds -> lower mp

Group 7: - Increases down the group as VDW forces stronger between molecules - More electrons causing movement of electrons - Increased temporary dipoles - Increased VDW forces -> More heat energy to overcome bonds -> Higher mp • States change O_O

• Fluorine = gas • Chlorine = gas • Bromine = liquid • Iodine = solid

Na, Mg, Al (rising): - They all have metallic bonding - Melting points increase due to increasingly positively charged ions - More electrons released as delocalised electrons - Therefore attractive electrostatic forces increase Si (the highest): - Apparently it’s a macromolecular - Has a very strong covalent structure - The covalent bonds need a lot of energy to break - Therefore Si has a very high melting point P, S, Cl, Ar (the lowest’s): - P, S & Cl are simple covalent - They have weak Van Der Waals forces - Intermolecular forces don’t need much energy to overcome - Therefore low melting points - Tho, melting point decreases from S to Ar - Due to decreasing size of the molecules For argon: - It’s a noble gas - Has individual atoms with a full outer shell of electrons - Atom is very stable - Van Der Waals forces between them very weak - Soooo, melting point very low - It’s just a gas at room temperature

Metalloids Properties of both metal & non-metals

Remember GCSE? The use of oil rig: - Reduction is gain of electrons - Oxidation is loss of electrons

• Oxidising agent causes oxidations of another species and are themselves reduced • Reducing agent causes reduction of another species and are themselves oxidised

How to tell if it’s a redox reaction?: - If the oxidation number changes, it’s a redox e.g. CH4 + O2 -> CO2 + H2O Notice the oxygen before and after If an element isn’t combined with anything, it’s oxidation number is 0 But now that it has combined, the oxidation number changed Get it?

Icl, use ur knowledge D: (that’s what he said, I’ll see what I can do)

Disproportionation reaction

• They are called alkaline (earth) metals • Reactivity increases down the group because: Nuclear charge increases Level of shielding increases Distance of 1st electron from nucleus increases Increases reactivity down the group • In addition, they always lose 2+ electrons to form 2+ ions every reaction • To achieve a full outer shell

• Produces a redox reaction • Producing metal hydroxide e.g. Mg + 2H2O -> Mg(OH)2 + H2 OIL occurs on Magnesium, and it’s the same with other group 2 elements • Magnesium reacts very slowly with liquid water • Therefore they use steam, which also provides extra energy • During reaction, magnesium burns with a white flame • Forming hydrogen & magnesium oxide, a white powder

• Reacts with pure oxygen • Producing simple oxides • But they would always have an oxidation number of 2+ • to balance with oxygen (-2) e.g. 2Mg + O2 -> 2MgO • Barium is an exception to this • Forms barium peroxide • Oxygen has -1 oxidation number e.g. Ba + O2 -> BaO2

• Reacts with OH- ions • Forms hydroxides • When writing formula, 2 hydroxide ions must be bracketed e.g. Mg2+ + 2OH- -> Mg(OH)2 • Solubility of group 2 hydroxides increases down the group • Mg(OH)2 = least soluble, Ba(OH)2 = most soluble • ∴, Magnesium hydroxide used in medicine as an antacid • as it’s alkaline and can neutralise acids • Or in agriculture to neutralise acidic soil

• Reacts with SO42- ions • Also forms hydroxides • The difference is solubility decreases down the group • and no brackets • MgSO4 = most soluble, BaSO4 = least soluble e.g. Ba2+ + SO42- = BaSO4 • Barium sulfate used in medicine as barium meals • as a medical tracer, imaging internal tissues or organs • Although the substance is toxic, it’s insoluble • Therefore can’t be absorbed in bloodstream and is safe

Wait…. no need

• Carbonates are formed by: Soluble group 2 salts + A solution containing carbonate ions (CO32-) e.g. Ca(NO3)2 aq + Na2CO3 aq -> CaCO3 s + 2NaNO3 aq tho ionic equation: Ca2+ (aq) + CO32- (aq) -> CaCO3 (s) • However, they undergo thermal decomposition (Splitting up a compound by heating it) • To give the metal oxide & carbon dioxide gas • All carbonates are white solids • Same with the oxides