QCE Chemistry. Year 2015 Mark 0.00 Pages 20 Published Jan 31, Chemistry: Revision Notes. By Sophie (1 ATAR)

Transcription

1 QCE Chemistry Year 2015 Mark 0.00 Pages 20 Published Jan 31, Chemistry: Revisin Ntes By Sphie (1 ATAR)

2 Pwered by TCPDF ( Yur ntes authr, Sphie. Sphie achieved an ATAR f 1 in 2016 while attending Shalm Cathlic Cllege Currently studying Bachelr f Science at The University f Queensland Achievements: Attended Natinal Yuth Science Frum 2016 Bilgy Subject Prize Chemistry Subject Prize Sphie says: Hi! I am an enthusiastic learner and in Years 11 and 12, I spent a lt f time making revisin ntes t make sure I was prepared fr exams. The way yu revise is cmpletely up t yu, hwever, I hpe yu can get a head start thrugh my ntes. Best wishes fr yur endeavurs ver the next years, Sphie.

3 Chemical symbls and cnventins Mass Number Charge f in Atmic Number (Number f prtns) Number f atms f that element in the mlecule r in Istpes - The number f prtns in the nucleus is what makes the element what it is - i.e. in a particular element, the number f prtns will always be the same - elements can have different numbers f neutrns (therefre the charge isn t effected) - Versins f an element with different numbers f neutrns are called istpes - Number f neutrns affects the atmic mass - 12 E.g. C, 13 C, 14C Relative atmic mass (RAM) - The mass number yu see n the peridic table - It is smewhat an average f the masses f the different istpes f the element - Hw cmmn each istpe is affects this - Calculating the RAM: - E.g. the three istpes f carbn: 12 6C, 13 6 C, 14 6 C - May be present in the wrld in the percentages f: 90% 1% 9% - Therefre: RAM = = The RAM f a mlecule can be fund just by adding the atmic mass f each element in the mlecule accrding t the quantity f it in the mlecule - E.g. CO 2 = 1 carbn, 2 xygen RAM = (atmic mass f carbn) + 2(atmic mass f xygen) = ( ) = 40 (apprx)

4 Slids, liquids and gases - The physical states f matter - Relatively easy t cnvert an element frm ne state t anther (e.g. heat, cl) - This is called a change f state - Slid: Definite vlume - Liquid - Gas Definite shape Difficult t cmpress Definite vlume Takes shape f cntainer Difficult t cmpress Expands t fill available space Takes shape f cntainer Easily cmpressed Particle nature f matter - Slid: Very rderly arrangement f particles Particles vibrate but dn t mve much - Liquid: Less rderly arrangement Translatinal vibratin (mvement) - Gas: Very unrderly arrangement Rapid translatinal mvement - Vibratin increases when heated Mixtures and pure substances, elements and cmpunds - Hmgeneus: unifrm cmpsitin (the same all the way thrugh) - Hetergeneus: nn-unifrm cmpsitin (visibly different parts in the mixture) - Mixtures: Parts can be easily separated Can be hmgeneus r hetergeneus Displays prperties f the pure substances that make it up Variable cmpsitin (ratis f pure substances can change) - Pure substance: Cannt be easily separated Always hmgeneus Prperties cnsistent thrughut Fixed cmpsitin - Element: cannt be in a simpler frm

5 - Cmpund: pure substances that can becme simpler (as they are cnstructed f several elements) Frmatin f Ins - Ins are charged elements can be psitively r negatively charged - Psitive ins are knwn as catins - Negative ins are knwn as anins - Elements becme charged by gaining r lsing an electrn - Inic bnding and the peridic table: Grup 1 want t lse an electrn (and becme +) Grup 2 want t lse tw electrns (and becme 2+) Grup 7 want t gain an electrn (and becme -) Grup 6 want t gain tw electrns (and becme 2-) Cvalent bnds - A bnd between tw nn-metals - Cvalent bnds frm mlecules (e.g. chlrine: Cl 2 ) - The atms share electrns t make bth happy with the electrn number - Occurs when bth elements need t gain electrns t attain Nble Gas cnfiguratins - The number f bnds frmed is the number f electrns required Prperties f inic and cvalent substances Inic: - Slids at rm temperature - High melting pints (due t strng electrstatic attractin between ins) - Hard and brittle - D nt cnduct electricity as slids but can when mlten r aqueus Cvalent: - Can be slid, liquid r gas at rm temperature - Lw melting/biling pints (weak attractin between mlecules)

6 Pwered by TCPDF ( - Sft as slids bnds are strng between atms but weak between mlecules - D nt cnduct electricity unless mlecules react with water t frm ins Cvalent Netwrk slids - Slids in which cvalent bnding extends indefinitely thrughut the whle crystal - Als called cvalent lattice slids r cvalent lattices - Inic slids are als inic lattices - Frmula fr the slid shws the rati f the elements in it - When melted, crystal breaks int many smaller crystals which mve relative t ne anther - Melting lattices requires a lt f heat and energy the frce is strng in them (haha). I.e. the bnds are strng within the slid - D nt cnduct electricity (except graphite) as electrns cannt ram Metallic bnding - Mst metals are slid, hard, have high melting pints, cnduct heat and electricity - Orderly array f psitive ins held tgether by a sea f delcalised electrns (this allws metals t cnduct electricity) - Valence/valency is a number that measures the cmbining pwer f the element when it frms cmpunds (fr ins, their valency is their charge) - Valence electrns break away frm their atms (hence delcalised ) and mve freely thrugh the lattice - Therefre, they prvide the chemical bnding that hlds the crystal tgether - This type f bnding als allws fr metals t be bent (malleable) and stretched int wires (ductile) as the electrns are able t adjust t the new in arrangements and be the glue Prperties f slids summarised Melting/biling pints Cnduct electricity Lattice Mlecular Metallic Inic Cvalent Lw Variable High High N Yes Only when mlten r aqueus Wrkability Sft Wrkable Brittle Brittle Frces hlding Inter-mlecular Delcalised Electr-static particles tgether electrns N Cvalent bnding thrughut