Structure and Physical Properties of Materials Flashcards
How does magnesium and oxygen chemically combine to make Magnesium Oxide?
Describe ionic bonds.
- Each magnesium atom loses 2 electrons and transfers it to the oxygen atom.
- Each oxygen atom gains 2 electrons from the magnesium atom.
- There are strong electrostatic forces of attraction between the magnesium cation and the oxygen anion.
How does carbon and oxygen chemically combine to form carbon dioxide?
Describe covalent bonds.
- Each Carbon atom shares 4 electrons oxygen. (to obtain a stable noble gas structure of neon)
- Each oxygen atom shares 2 electrons with carbon. (to obtain a stable noble gas structure of neon)
- There are strong covalent bonds formed between carbon atoms and oxygen atoms in the carbon dioxide covalent compound
Describe the bonding and structure of an ionic compound.
- Has a giant ionic crystal lattice
- three-dimensional network of cations and anions
- held by strong electrostatic forces of attraction between cations and anions
Describe the bonding and structure of a simple covalent compound.
- Has a simple molecular structure
- Exist as small discrete molecules(individual molecules)
- held by weak intermolecular forces of attraction between molecules
Describe the bonding and structure of a metal.
- Has a giant metallic structure
- With a lattice of cations surrounded by ‘sea’ of delocalised electrons
- strong electrostatic attraction between positive ions (cations)and delocalised electrons
Why can’t an ionic compound conduct electricity in its solid state?
- Ions are held in fixed positions by strong ionic bonds.
- No free moving ions to conduct electricity.
Why can an ionic compound conduct electricity in molten or aqueous state?
- Giant crystal lattice structure breaks down.
- Ions are able to move freely to conduct electricity
Why does a simple covalent compound not conduct electricity in all states?
- Covalent compounds exists as molecules. → No free moving ions to conduct electricity.
- All valence electrons used up for bonding. → No free moving electrons to conduct electricity.
No mobile charge carriers.
Why can a metal conduct electricity?
- Presence of delocalised electrons which can move freely throughout the metallic structure (when a potential difference is applied)
Describe the structure and bonding of a polymer.
- Made of large molecules / macromolecules held together by intermolecular forces of attraction
- Polymer has a bigger molecular mass than an individual molecule (Simple Covalent Substance)
Why does a polymer have a higher m.p and b.p than an simple covalent compound?
- Polymer has a larger molecular mass than a simple covalent compound.
- Hence the intermolecular forces of attraction are stronger than those between molecules in simple covalent compounds
Describe structure and bonding of silicon dioxide.
- Giant molecular structure consisting of a giant network of silicon and oxygen atoms in a 3D tetrahedral structures
- **Held by strong covalent bonds **between silicon and oxygen atoms
Describe structure and bonding of diamond
- Giant molecular structure consisting of a giant network of carbon atoms in a 3D tetrahedral structures
- Held by numerous strong covalent bonds between carbon atoms
Describe structure and bonding of Graphite
- Giant molecular structure consisting of a **huge network of atoms with layers of carbon atoms **
- Held by weak intermolecular forces of attraction between the layers
Why can graphite be used as a lubricant?
- Layers of carbon atoms are held by weak intermolecular forces of attraction
- Layers can slide over one another easily
