7.3 - Periodic Trends - Bonding and Structure Flashcards Preview

OCR A Chemistry A Level - Chapter 7 > 7.3 - Periodic Trends - Bonding and Structure > Flashcards

Flashcards in 7.3 - Periodic Trends - Bonding and Structure Deck (9)
Loading flashcards...

What are metalloids?

An element whose properties are intermediate of metals and non-metals.


What are constant properties of almost all metals?

- All conduct electricity
- All metals bar mercury are solid at room temperature


Describe the process of metallic bonding.

Each atom in a solid metal structure donates 1 electron to a pool of delocalised electrons - which are mobile throughout the structure.
- This leaves cations in fixed positions which maintain the structure.

Metallic Bonding: The electrostatic attraction between cations and delocalised electrons

- Metallic structures have no charge as there are as many ionic charges as there are delocalised electrons.


Define giant metallic lattice.

3D structure of +ve ions and deloclised electrons bonded by strong metallic bonds with many atoms


What are the properties of metals?

High electrical conductivity - Solid state metals can conduct electricity due to the delocalised electrons being mobile and being able to carry a charge.

High MP/BP - MP/BP depends on strength of metallic bonds. Strong electrostatic attraction means more energy required to break the bonds.

Metals are Insoluble
Metals have Strong Electrostatic Forces of Attraction


Define giant covalent structure and elements that have it.

3D structure of billions of atoms bonded by strong covalent bonds (has no intermolecular force)
- Carbon and silicon in Group 4


Describe the giant covalent structures of carbon and silicon.

Both carbon (except in graphite and graphene) use their 4 electrons to bond to make giant covalent structures with no delocalised electrons.
- Diamond - tetrahedral bond angle 109.5


What are the properties of giant covalent structures?

High MP/BP - large amounts of energy needed to overcome string covalent bonds (no intermolecular forces)

Giant Covalent Lattices are Insoluble - covalent bonds too strong to be broken by solvent interaction

Giant Covalent Lattices are non-electrical conductors - no delocalised electrons - except for graphite and graphene


What are periodic trend in melting points?

Across Period 2 & 3...
- Increase in MP from G1>G4
- Sharp decrease from G4>G5 - signals change from giant structures of G1>G4 to simple molecular structures with int molecular forces
G5>8 low MP