4.4 Metallic bonding and Allotropes

Define the term allotropes

• Atoms with same proton number but different number of neutrons
• Atoms with same proton number but different mass number
• Atoms in different arrangement in structure
• Atoms in different arrangement and different physical form

Graphene is a good conductor because

• free moving electrons
• free delocalization of electrons in its structure
• free delocalized electrons in 2D structure
• free delocalized electrons in 3D

What kind of bonding does atoms in graphene has?

• Covalent bonding
• Each carbon, bonded covalently to 3 other carbon atoms.
• Each carbon, bonded covalently to 4 other carbon atoms.
• Each carbon, bonded covalently to 3 other carbon atom in 2D

Why graphene is a better conductor compared to C₆₀?

• More delocalized electrons in graphene
• Electron move easily in graphene
• Electron move easily due to its planar flat structure
• Electron movement easier due to weak attraction with nuclei

Which of the following is true about C₆₀ ?

• Each carbon bonded covelently to 3 other carbon atoms
• Each carbon bonded covelently to 4 other carbon atoms
• 2 single and 2 double bonds in its structure
• Hexagonal and pentagonal in shape

C₆₀ is a good conductor because

• It has one delocalized electron moving freely
• It has 60 delocalized electrons moving freely
• Free moving electrons
• Free moving delocalized electrons

Define the term metallic bonding

• Attraction between positive nuclei and electrons
• Forces attraction between nuclei and electron
• Forces attraction between nuclei and sea of electrons
• Electrostatic attraction between nuclei and sea of electrons

Tags

NGSS.HS-PS1-3

Why melting point increase across period 3, from Sodium (Na) to Aluminium (AI)?

• Size of atoms get smaller
• Attraction force between nuclei and free electron increase
• More free moving electrons
• Due to increase of sea of electron and size of atomic nuclei

Why melting point decrease down group 1?

• Increase in size of atom down the group
• Increase in number of sea of electrons
• Increase in number of protons in nucleus
• Decrease in attractive force due to rise in proton number

Gp 4, Diamond (C) and Silicon (S) has highest melting point due to

• Strong covalent bonds between carbon atoms
• All carbon atoms are covalently bonded
• Strong covalent bonds in a macromolecular structure
• Carbon atom covalently bonded in a macromolecular structure