Bonding Flashcards
What is ionic bonding?
Electrostatic attraction between oppositely charged ions formed by the transfer of electrons from a metal to a non-metal.
Forms giant ionic lattices (e.g. NaCl) and has high melting and boiling points due to strong ionic bonds.
What are the key points of ionic bonding?
- Forms giant ionic lattices (e.g. NaCl)
- High melting and boiling points due to strong ionic bonds
- Conduct electricity only when molten or in solution
- Brittle due to layers of ions sliding and same charges repelling
What is covalent bonding?
A bond formed when two atoms share a pair of electrons.
Each atom contributes one electron.
What are examples of molecules with covalent bonds?
- H₂
- O₂
- CO₂
- CH₄
What are the two types of covalent structures?
- Simple molecular: Low melting/boiling points
- Macromolecular: Strong covalent bonds throughout the structure
What is dative (coordinate) bonding?
A covalent bond in which both electrons come from the same atom.
Example: NH₄⁺ — nitrogen donates a lone pair to H⁺.
What is metallic bonding?
Electrostatic attraction between positive metal ions and a sea of delocalised electrons.
More delocalised electrons result in stronger bonds.
What are the key points of metallic bonding?
- High melting/boiling points
- Conduct electricity and heat
- Malleable and ductile due to non-directional bonding
What is electronegativity?
The ability of an atom to attract a bonding pair of electrons in a covalent bond.
What is the trend of electronegativity across a period?
Increases across a period (more protons, same shielding).
What is the trend of electronegativity down a group?
Decreases down a group (more shielding, larger atomic radius).
Which atom is the most electronegative?
Fluorine (F).
What determines bond polarity?
If atoms have different electronegativities, electrons are pulled unequally, resulting in a polar bond.
What is van der Waals force?
Temporary dipoles induce dipoles in neighbouring molecules.
Present in all molecules; strength increases with molecular mass or surface area.
What is a permanent dipole-dipole interaction?
Attraction between the permanent dipoles of polar molecules.
What is hydrogen bonding?
Strongest IMF; occurs when H is bonded to N, O, or F, and interacts with a lone pair on another molecule.
What are the key points of hydrogen bonding?
- High boiling points (e.g., H₂O, NH₃)
- Responsible for ice’s lower density than water
- Shown as a dotted line from lone pair to H
What is the VSEPR theory?
Electron pairs repel each other and arrange to minimise repulsion.
What is the bond angle and shape for a linear molecule?
Bond Angle: 180°; Shape: Linear
Example: CO₂.
What is the bond angle and shape for a tetrahedral molecule?
Bond Angle: 109.5°; Shape: Tetrahedral
Example: CH₄.
What is a giant ionic lattice?
- Strong electrostatic forces
- High melting points
- Conductive when molten/aqueous
What are the properties of a giant covalent structure?
- Diamond: tetrahedral, hard, non-conductive
- Graphite: layered, conductive, lubricating
What are the properties of a metallic structure?
- Layers of cations in delocalised electron sea
- High melting points
- Conductive
- Malleable
True or False: Atoms have charges in covalent bonding.
False. Use ‘partial charges’ or dipoles if polar.
What must be shown in diagrams for hydrogen bonding?
- Lone pairs
- δ+ and δ–
- Hydrogen bond line
What is a common pitfall in molecular polarity?
Mixing up ‘molecular polarity’ with ‘bond polarity’.
What should be included in an exam response for shapes of molecules?
- Number of bonding/lone pairs
- Shape
- Angle
- Repulsion rule
