metallic bonding

Question 1

define metallic bonding

Answer 1

the electrostatic forces of attraction between a sea of delocalized (does not belong to one particular atom) valence electrons and metal cations

Question 2

explain how metallic bonding works

Answer 2

Metallic substances achieve stable noble gas configurations as metals hv low first ionisation energies - loose electrons easily - therefore in a solid and liquid states metal atoms release outer shell/valence electrons so they are free to move among positive ions produced in this ionisation process - delocalised electrons + positive

Question 3

describe the bonds in metallic bonding

Answer 3

metallic bonds are non-directional as delocalised electrons are not attracted to a particular ion and are free to move between cations, and bond randomly in any direction

Question 4

what is the structure of a metal/how is it arranged?

Answer 4

in solid state ions occupy fixed positions in a 3D lattice
- in liquid state they are arranged randomly

Question 5

draw a diagram of metallic bonding

Question 6

what does the strength of a metallic bond rely on?

Answer 6

1. charge of positive ions → e.g. Potassium only donates 1 valence electron to delocalized cloud whereas Mg donates 2 valence e’s thus potassium has weaker metallic bonding than Mg
2. size of positive ions - greater the size, greater the strength of the metallic bond
3. way in which positive ions are organized in lattice

Question 7

explain in metallic bonding the physical property of: melting point/boiling point

Answer 7

1. strong electrostatic force of attraction between metal cations and sea of delocalised valence electrons
2. large amounts of energy required to overcome strong intramolecular bonding between metallic bonds in lattice between cations and valence electrons to turn metal from solid → liquid /liquid → gas
3. therefore high melting point and boiling point

Question 8

explain in metallic bonding the physical property of: electrical conductivity

Answer 8

in order to conduct electricity substance needs charge + mobility:

• delocalized electrons are mobile charge carries as they can move freely through structure (non-directional bonds)
• metal cations are positively charged

Question 9

explain in metallic bonding the physical property of: malleability

Answer 9

• when metals are bent/streched positive ions are forced to move relative to each other however no matter where cations are shifted, delocalised electrons are free to move between cations keeping structure together by ensuring electrostatic attraction remains and metallic bonds are maximised this is due to the non-directional bonding of valence electrons to cations

Question 10

explain in metallic bonding the physical property of: ductility

Answer 10

metals shape can be deformed without affecting metallic bonds due to non-directional bonding in metals

Question 11

explain in metallic bonding the physical property of: high lustre (shiny)

Answer 11

interaction between photons of light from external light source and mobile sea of delocalised electrons on surface of metal lattice creates typical metallic reflection/shininess

Question 12

explain in metallic bonding the physical property of: thermal conductivity

Answer 12

• delocalised electrons are mobile so can carry heat energy (as kinetic energy) throughout metal lattice
• vibration of metallic ions also contributes to flow of heat through metal lattice