CfE Higher Supported Study Week 1 Bonding in first 20 elements

Key Areas Bonding and Structure in first 20 elements Metallic Covalent Molecular Covalent Network Monatomic

Metallic Metallic structure – consists of giant lattice of positively charged ions and delocalised outer electrons

Covalent Non – metals Sharing Electrons Attraction between positive nuclei and negative shared electrons. Recap of Nat 5 material.

Covalent molecular consists of discrete molecules held together by weak London dispersion forces

Phosphorus – P4 Need to know Phosphorus is a solid and be able to draw one of structures on right, chose one, commit to memory.

Sulphur – S8 Sulphur is an S8 ring, a solid at room temperature. Drawn as 8 sulphurs in a ring. Higher Bp/Mp than Phosphorus as more atoms, more electrons so stronger LDF’s

LDF’s Temporary Dipoles caused by uneven distribution of electrons Reminder about definition of LDF’s and how they arise (Dipole definition is a separation of charge, positive at one end, negative at another)

Covalent molecular What other element has a covalent molecular form??

Fullerene C60 Lots of different sizes Discrete Molecules Carbon – fullerenes can have many different number of carbons, 60, 120, 240 etc. They contain a specific number of carbons compared to network which is extensive number of carbons. Common question – difference in structure between fullerenes and graphite/network. Fullerenes are covalent molecular structure Diamond/graphite are network structures.

Covalent network structure Boron, Carbon (diamond and graphite), silicon are network structures. Extra notes about graphite structure in slides. Carbons only form 3 bonds, contains delocalised electrons, hence why graphite conducts electricity.

Monatomic structure Monatomic – one atom / single atoms Noble gases Only LDFs overcome on melting and boiling

Answer – D