GCSE WJEC Chemistry- bonding

why is diamond very hard

strong covalent bond

hydrogels

cross linked polymer structure influtes with solvent

why graphite has very high MP+BP

strong covalent bonds

ionic compounds MP+BP

high

simple molecular/ giant covalent bond

non-metal X2

nano silver use

anti-bac sprays → sterlising

nano titanium dioxide use

sunscreen (blocks UV) + self-cleaning glass (hydroliphic- water <3)

thermochromic paint use

thermometer

shape memory polymer

can gain original shape when heated

shape memory alloy

pseudo- elasticity, shape retenition memory

ionic bond

metal + non-metal

shape memory alloy example

braces

photochromic paint example

sunglasses

shape memory polymer example

self- repairing car body

photo- chromic paint

paint that changes with light

thermo-chromic paint

paint that changes with heat

2 hydrogel uses

nappies + artificial muscles

why metals conduct electricity

outer electrons free to move + carry a charge

when does ionic compound conduct electricity

when dissolved in water/ molten

metallic bond

metal X2

covalently bonded structure w 60 carbon atoms + football shape

buckminsterfullerene

does diamond or graphite conduct electricity

graphite

why does graphite conduct electricity

4th outer shell electron on carbon atom is free to move + carry charge

why cant diamond conduct electricity

no free electrons to carry a charge

is diamond or graphite soft

graphite

does simple molecular conduct electricity

no

2 properties of carbon nanotube

conducts electricity + very small

why metals have high MP + BP

difficult to separate ions due to strong forces of attraction

why simple molecular have low MP+BP

only weak forces of attraction holding them together

nano- particle size

1-100 nm

use of nano particle problems

dont know long term effects- could cause lung inflammation + cancer

2 examples of giant covalent substances

diamond + graphite

Name this

Carbon nanotube

Name this

Diamond

Name this

Graphite

Name this

Graphine

What bonding exists in CO₂

covalent

Two differences between structures of diamond and graphite

graphite has layers but diamond doesn’t + graphite has free electrons, but diamond doesn’t