Bonding

Question 1

what are the types of bonding?

Answer 1

ionic
covalent
metallic

Question 2

what is an ionic bond?

Answer 2

• happen between metals and non-metals
• metal loses electrons=positive ion=cation
• non-metal gains electrons=negative ion=anion

Question 3

properties of ionic compounds

Answer 3

• giant regular ionic structure (ionic lattice)
• strong electrostatic forces in all directions between ions=high m.p/b.p
• only conduct electricity when molten or dissolved

Question 4

what is a covalent bond?

Answer 4

when non-metals share their outershell electrons eg. Cl2(single)
O2(double)
N2(triple)

Question 5

what are the types of covalent structures?

Answer 5

• small molecules
• giant covalent structures
• polymers

Question 6

properties of small molecules

Answer 6

• low m.p/b.p= liquids or gases
• weak intermolecular forces=easily overcome when heated
• don’t conduct electricity= no charge or delocalised electrons to carry current
• volatile

Question 7

properties of giant covalent structures

Answer 7

• high m.p/b.p= solids
• atoms joined by strong covalent bonds
• rigid structures
  eg. diamond, silica

Question 8

properties of polymers

Answer 8

• large molecules
• atoms are linked together by strong covalent bonds
• strong intermolecular forces = solid at room temp

Question 9

what is a metallic bond?

Answer 9

• between 2 metals in a sea of delocalised electrons
• strong electrostatic forces between + ions and - electrons

Question 10

properties of metallic compounds (metals)

Answer 10

• giant structure = high b.p/m.p
• regular arrangement
• ‘soft’

Question 11

what are alloys and why are they used?

Answer 11

a mixture of 2 or more elements, with at least 1 is a metal
- they’re harder then pure metals = different sized atoms distort regular arrangement

Question 12

limitations of gas, liquid, solid model

Answer 12

• no forces
• particles are represented as
  spheres
• spheres are solid.

Question 13

allotropes of carbon

Answer 13

diamond
graphite
graphene
fullerene

Question 14

properties+uses of diamond

Answer 14

• each carbon atom bonds with 4 other carbon atoms in a giant covalent structure
• very hard,
• very high melting point
• doesn’t conduct electricity
  used in industries=cutting tool

Question 15

properties+uses of graphite

Answer 15

• each carbon atom bonds with 3 other carbon atoms=one free, delocalised electron=conducts electricity
• layers of graphene=weak intermolecular forces= slide over eachother= soft+slippery
• high mp/bp= strong covalent bonds
  used in pencils, lubricants, electrodes

Question 16

properties+uses of graphene

Answer 16

-layer of graphite
- conducts electricity= delocalised electrons
- light (in mass)
- strong (due to covalent bonds)
- used in electronics and composites.

Question 17

properties+uses of fullerenes

Answer 17

• Buckminster fullerene (C60) first to be discovered=sphere
• carbon molecules which are hollow
• hexagonal rings (or 5 or 7)
• good catalysts
• deliver drugs
• carbon nanotubes are cylindrical fullerenes
• used in nanotechnology, electronics and materials.

Question 18

types of particles

Answer 18

coarse (1 x 10-5 m and 2.5 x 10-6 m )
fine (1 x 10-7 m and 2.5 x 10-6 m)
nanoparticles (1-100 nm)

Question 19

properties+uses of nanoparticles

Answer 19

• large sa:v ratio
• less of them for the same effect
• silver nanoparticles=antibacterial= used in deodorants+wound dressings
• absorbed easily
• used in cosmetics, sun creams, catalysts, electric circuits
• nanoscience is new=potential long term risks