| resources for science ...€¦ · Topic Simple chemical formulae for molecules Level GCSE (orany course forstudents aged 11-16) Outcomes Understand that molecules can be represented

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Topic Simplechemicalformulaeformolecules

Level GCSE(or anycoursefor studentsaged11-16)

Outcomes Understandthatmoleculescanberepresentedindifferentways(molecularformula,displayedformula,dotandcrossdiagram)andthatdifferentrepresentationshavedifferentuses

Identifythenumberofeachatomofeachelementpresentinamoleculeusingthemolecularformula

Informationforteachers

Thisresourceasksstudentstothinkaboutwhatamolecularformulatellsusaboutachemicalsubstance.Youwillneedtoadaptthisactivityifyouhaven'tcoveredcovalentbondingyet(slide3and4).Itishelpfultohavesomegeneraldiscussionaroundmethanebeforemovingintotheabstractworldofrepresentations.

Pedagogyfocus Usingdifferentrepresentationsinchemistry.

Otherresources

Otherresourcesonequationsandformulaearehere:https://thescienceteacher.co.uk/moles/

Whatonearth?!

Source:https://www.dailyrecord.co.uk/news/weird-news/cow-fart-crackdown-california-creates-9361672

CH4

CompletetheVenndiagramtodescribesimilaritiesanddifferencesbetween therepresentationsofmethane.

Shows 4 electron pairs involved in bonding

CH4

CompletetheVenndiagramtodescribesimilaritiesanddifferencesbetween therepresentationsofmethane.

Made from the elements carbon and hydrogen

1 C and 4 H atoms

Shows 4 C-H bonds

Shows methane is covalent

Shows 4 electron pairs involved in bonding

Shows positions of bonds (not 3D)

Can be typed

A bond is represented as a dot and cross

A bond is represented as a line

No bonds shown

Use same symbols

Uses a subscript

Whichrepresentationismostusefulfor…

a) writingachemicalequation?b) workingoutwhatelementsarepresent?c) workingouthowmanybondsarepresent?d) workingoutifthesubstanceisionicorcovalent?

CH4

displayedformula molecularformuladotand cross diagram

Formula NameYouhaveseenthissubstance

before…

Elementnames Numberofatoms

1 CH4 methane Gasstovesforcooking

Carbonandhydrogen

1xC4xH

2 H2S hydrogensulfide

Rotteneggsmell– flatulence

3 O2

4 Fireextinguishers 1xC2xO

5 CH3COOH Puttingonchips

6 C12H22O11 sucrose Tablesugar

7 Usedtobleachhair

2xH2xO

8 C8H10N4O2 caffeine

9 C8H9NO2 paracetamol

10 copper