Chemical Bonding Flashcards
What are noble gases?
Noble gases belong to the only group where elements’ atoms already have complete valence shells. We refer to this stable arrangement of electrons as noble gas configuration.
What’s with elements in Group I and III?
Elements in Group I to III tend to lose electrons in order to achieve noble gas configuration, forming positive ions → METALS
What’s with elements in Group V to VII
Elements in Group V to VII tend to gain electrons in order to achieve noble gas configuration, forming negative ions → NON-METALS
Where does the staircase line start?
Above aluminium, goes down
Describe ionic bonding
Ionic bonding is the transfer of electrons from a metallic atom to a non-metallic atom in order to achieve noble gas configuration. Hence, both elements involved achieve a full valence shell.
Describe covalent bonding
Covalent bonding is the sharing of electrons between two or more non-metallic atoms
in order to achieve noble gas configuration.
Describe the structure, bonding and energy of ionic bonding
S: Giant ionic lattice of positive and negative ions
B: Held together by strong electrostatic forces of attraction
E: High m.p. as a large amount of energy is needed to overcome the strong electrostatic forces between the ions
Describe the structure, bonding and energy of covalent bonding
S: Small molecules
B: Loosely held together by weak intermolecular forces of attraction
E: Low m.p. as a small amount of energy is required to overcome the weak intermolecular forces between the molecules.
How is the electrical conductivity of GILS and SMS?
GILS have poor electrical conductivity as solids as there are no mobile ions, but are good electrical conductors in liquid/aqueous states.
Simple molecular structures (SMS) have poor electrical conductivity in ALL STATES as there are no mobile ions
Are GILS and SMS soluble in water? Name exceptions
GILS are generally soluble in water. Exceptions include SILVER CHLORIDE.
SMS are generally insoluble in water. Exceptions include AMMONIA and CHLORINE
How is the strength of electrostatic forces of attraction determined?
Magnitude of charge: The larger the charge (2+ vs. +), the stronger the electrostatic forces.
Physical size of ions: The larger the size, the further apart the ions and the weaker the electrostatic forces.
Name one defining factor of the strength of intermolecular forces of attraction, and how it affects m.p. and b.p.
Size of the molecule: The larger the molecule, the greater the intermolecular forces (assuming all other factors remain constant)
If the strength of the forces of attraction are higher, the melting and boiling points are higher.
Explain what is formed in metallic bonding.
A metallic lattice structure forms which is a lattice of positive ions in a sea of delocalised electrons.
How do we know the number of delocalised valence electrons?
The number of valence electrons delocalised depends on the corresponding group number in the Periodic Table.
→ The more electrons are delocalised, the higher the melting point.
What are the five properties of metals?
- have moderate to high melting points
- good electrical conductivity whether solid or molten
- insoluble in water (but can react)
- malleable and ductile texture
- shiny, grey (except gold and copper) appearance
What is a macromolecule? How is it different from SMS?
Giant molecular structure where every atom is covalently bonded together.
This is unlike simple molecular substances, which have both covalent bonds and intermolecular forces of attraction.
Why do macromolecules have high melting point?
Macromolecules have a high melting point as a lot of energy is needed to break the strong covalent bonds.
What is the key quality of diamond?
Used in saw blades and drill bits as they are VERY HARD.
What are graphite’s properties?
- Graphite has a soft and slippery texture
- Graphite has good electrical conductivity
Describe the structure of graphite.
Graphite’s carbon atoms only form three bonds each, and the last valence electron is delocalised. → Graphite has layers of carbon atoms covalently bonded in a hexagonal arrangement, where there are weak intermolecular forces of attractions between each layer. For each layer, the carbon atoms are bonded together by strong covalent bonds.
