2.1 Bonding, Structure and Properties Flashcards
Properties of metals (5)
- malleable and ductile
- conduct electricity
- conduct heat
- high melting and boiling points
- react with oxygen to form basic oxides (reactivity varies)
Structure of metallic bonding
Electrons from outer shells of atoms are delocalised- free to move throughout the structure
Why are there strong metallic bonds in metals and what makes them so strong
Positive ions share delocalised electrons
The bond is strong because of strong electrostatic forces between positive metal ions + and negative electrons -
Explain the electrical conductivity of metals
Delocalised electrons carry electrical charge throughout the structure
Explain the thermal conductivity of metals
Delocalised electrons and closely packed ions transfer energy throughout the structure by conduction
Free electrons move faster and conduct heat, also vibration of particles
Why are metals malleable and ductile
Layers of metal ions can slide past each other when hammered/stretched
Why do metals have high melting and boiling points
Large amounts of energy are needed to break the strong metallic bonds
What happens to the melting and boiling points of metals as you move across a period and why
Increase
There are more delocalised electrons, increasing the (electrostatic forces &) attraction between the + ions and - free electrons (stronger bonds)
What is an ion
A charged particle
Giant ionic structure definition
Positive and negative ions held together by strong electrostatic forces in a regular 3D lattice
Each + ion attracts all the - ions around it
Why do giant ionic structures have high melting and boiling points
Due to strength of electrostatic forces between the ions
When do giant ionic structures only conduct electricity and why
Only when dissolved or molten
Only them are the ions free to move to carry the charge
Why are giant ionic compounds brittle
Ion layers are shifted and jump over each other
Ions of the same charge are brought side by side and repel each other
Properties of giant ionic structures
High melting and boiling points
Conduct electricity when dissolved or molten
What are simple molecular/covalent structures and examples
A few atoms held together by covalent bonds
H, H20, CO2
Properties of simple covalent/molecular structures
Low melting and boiling points
Do not conduct electricity
Explain why simple covalent structures have low melting and boiling points
Due to weak inter molecular forces (forces between molecules)
Explain why simple molecular/covalent structures don’t conduct electricity
No free electrons to carry electric current