Bonding and structure Flashcards
What is an orbital?
A region of space around the nucleus that can hold up to 2 electrons with opposite spins.
Define average bond enthalpy
The average energy required to break a bond, used as a measurement of the strength of a covalent bond. The average bond enthalpy is measured using a variety of molecules that contain a specific bond.
What is a covalent bond?
A strong bond formed between 2 atoms due to the electrostatic attraction between a shared pair of electrons and the atomic nuclei.
What is a dative covalent bond?
A type of covalent bond in which both of the electrons in the shared pair come from one atom.
Define electronegativity
The ability of an atom to attract bonding electrons in a covalent bond.
What is electron pair repulsion theory?
Pairs of electrons around a nucleus repel each other so
the shape that a molecule adopts has these pairs of electrons positioned as far apart as
possible. Lone pairs offer more repulsion than bonding pairs as they are closer to the nucleus of the central atom.
What is hydrogen bonding?
A type of intermolecular bonding that occurs between molecules
containing N, O or F and a H atom of -NH, -OH or HF. A lone pair on the electronegative
atom (N, O or F) allows the formation of a hydrogen bond.
What is an ionic bond?
(a bond caused by the) electrostatic attraction between positive and negative ions
What is an ionic lattice?
A giant structure in which oppositely charged ions are strongly attracted in all directions.
What are london forces?
Induced dipole-dipole interactions caused when the random movement of electrons creates a temporary dipole in one molecule which then induces a dipole in a neighbouring molecule.
What is a lone pair?
A pair of outer-shell electrons not involved in bonding.
What are macroscopic properties?
Properties of a bulk material rather than the individual atoms/
molecules that make up the material.
What is a permanent dipole?
A permanent uneven distribution of charge.
What is a polar bond?
A covalent bond that has a permanent dipole due to the different
electronegativities of the atoms that make up the bond.
What is a polar molecule?
A molecule that contains polar bonds with dipoles that don’t cancel out due to their direction (must be unsymmetrical).
What is a simple molecular lattice?
A solid structure made up of covalently bonded molecules attracted by intermolecular force (e.g. I2 and ice). These compounds generally have relatively low melting and boiling points and are typically insoluble in water but soluble in organic solvents. Molecular substances don’t conduct electricity.
How many bonding and lone pairs for a linear shape?
2 bonding
How many bonding and lone pairs for a non-linear shape?
2 bonding, 2 lone
How many bonding and lone pairs for a trigonal planar shape?
3 bonding
How many bonding and lone pairs for a trigonal pyramidal shape?
3 bonding, 1 lone
How many bonding and lone pairs for a tetrahedral shape?
4 bonding
How many bonding and lone pairs for an octahedral shape?
6 bonding
How many bonding and lone pairs for a trigonal bipyramidal shape?
5 bonding
