Bonds, Structure & Properties of Matter Flashcards
3 types of bonding
Ionic, Covalent, Metallic
Ionic Bonding
- Non-metal + Metal
- Electrostatic forces attract the oppositely charged ions
Covalent Bonding
- Non-metal + Non-metal
- Atoms share pairs of electrons
- Strong bonds
Metallic Bonding
- Metal + Metal
- Positive metal ions + delocalised electrons produce electrostatic force
Ionic Compounds
- Giant structure
- Held together by strong electrostatic forces of attraction between oppositely charged ions
- Eg. Sodium Chloride
Limitations of Dot and cross diagrams, 3D models for representing IONIC COMPOUNDS
- Does not show how the ions are arranged in space
- Only 2D
- Not to scale
- No information about forces of attraction of ions
Giant covalent structure examples
- Diamond
- Silicon Dioxide
3 states of amtter
Solid, Liquids and Gases
What takes place at melting point?
Melting and freezing
What takes place at boiling
Boiling and condensing
What determines the amount of energy required to change a substances state?
The strength of the forces between the particles of the substance
Type of bonding and structure of substance
The stronger the forces, the higher he melting point
What are the limitations of the simple particle model of matter?
- There are no forces between particles
Properties of ionic compounds
- High melting and boiling points (large forces of attraction between particles)
- When melted or dissolved in water, they can conduct electricity because ions are free to move so charge can flow
Properties of small molecules
- Low melting and boiling points
- Weak forces of attraction, (INTERMOLECULAR FORCES OVERCOME and NOT COVALENT BONDS)
- Cannot conduct electricity, because small molecules have no charge
What is a polymer?
Made of chains of monomers
Atoms in polymer molecules are linked to other atoms by strong covalent bonds
Giant covalent structures
- Solids with very high melting points
- All linked by strong covalent bonds
- ## These bonds must be overcome to boil the substance
Properties of metals and alloys
- High melting and boiling points
- Arranged in layers, so malleable
- Alloys are less malleable and harder
Why are metals good conductors of electricity?
Delocalised electrons in metal carry charge through metal.
Also good conductor of thermal energy because delocalised electrons transfer energy
Diamond
- 4 covalent bonds with each CARBON atom
- Giant covalent structure
- So is very hard
- High melting point
- Does NOT conduct electricity
Graphite
- Each CARBON atom forms 3 covalent bonds with 3 other carbon atoms
- Forms layers of hexagonal rings with no covalent bonds between layers
- High thermal and electrical conductivity, one delocalised electron per carbon atom
- High melting and boiling point
Graphene
Single layer of graphite and has properties making it useful in :
- Electronics
- Composites
What are fullerenes
- Molecules of carbon atoms with hollow shapes
- hexagonal rings of carbon atoms
Uses of fullerenes
Eg. Carbon nanotubes
- Nanotechnology
- Electronics
- Materials
What happens to the surface area and volume ratio when the side of a cube decreases by a factor of 10?
Surface area to volume ratio increases by a factor of 10
Nanoparticle uses
- Medicine
- Electronics
- Cosmetics
Advantages and disadvantages of nanoparticles
Advantages :
- Faster technology
- Life saving medicine treatment
- More efficient power sources
Disadvantages :
- Possible threats to health
- Possible threats to environment
- Possible threat to security, privacy
