Bonding and Structure Flashcards
What is ionic bonding?
Bonding between metal and non-metal ions.
How does an ionic bond occur?
A transfer of electrons forming positive and negative ions.
What properties to ionically bonded compounds have?
High melting points due to strong electrostatic attractions.
Conduct electricity when dissolved or molten as ions aren’t fixed in a lattice.
Mostly soluble
What is a metallic bond?
Attractions between positive metal ions and delocalised electrons.
The strength depends on the charges and sizes of the metal ions.
What are the properties of metallically bonded compounds?
High melting points due to stong attractions.
Always conduct electricity.
What is covalent bonding?
Localised attraction between two non-metal atoms.
How does a covalent bond occur?
Electrons are shared in pairs between atoms, with a shared pair of electrons being attracted to the nuclei of both bonding atoms.
What properties do covalently bonded molecules have?
Low melting points due to weak intermolecular bonds.
Don’t conduct electricity.
What is a dative covalent bond (co-ordinate bond)?
Same as a covalent bond, but both electrons in the bond came from the same atom.
What is electronegativity affected by?
Nuclear charge - if it has more protons, it’s got a stronger attraction. Increases electronegativity.
Atomic radius - smaller means stronger attractiion from nucleus as smaller distance. Increased electronegativity.
Electron shielding - less shells means smaller distance and stronger attraction from nucleus. Increased electronegativity
What is another name for London forces?
Induced dipole - induced dipole interactions
How are London forces formed?
Caused by constant, random movement of electrons. Forms an instantaneous dipole across a molecule which induces a dipole in close molecules.
What increases the strength of London forces?
Larger number of electrons, and a larger surface area.
What is a permanent dipole - permanent dipole interaction?
An intermolecular bond between the delta+ atom of a molecule and the delta- atom of another molecule.
What is hydrogen bonding?
Hydrogen is covalently bonded to oxygen, nitrogen, or fluorine (lone pair of electrons). The strongest of all the intermolecular bonds.
