2. Mocks revision Flashcards
Ligand definition, what do ligands differ in?
a neutral molecule (or anion) that contains a non-bonding pair of electrons that can form coordinate (dative) covalent bonds with metal ions and form complex ions
ligands differ in how many lone pairs they donate (one, two, six)
Types of ligands and examples of different types
monodentate: H2O, F-, CL-, NH3, OH-, SCN-, CN-
bidentate: 1,2 diaminoethane (H2NCH2CH2NH3), ethanedioate (C2O4)2-
polydentate: EDTA (ethylenediaminetetraacetic acid)
What is the coordination number and how does it determine the shape of a complex ion?
the number of lone pair bonded to the metal ion
complex ions with CN 2 have a linear shape, with CN 4 have either square planar or tetrahedral, and with CN 6 have an octahedral shape
Why are some complex ions colorless and if they are not, what determines their color?
if compounds have no d-shell electrons or if they have a complete d shell
if they have incomplete d shell then the color is determined by:
1| The nature of the transition metal
2| The oxidation state of the transition metal
3| The identity of the ligand
4| The stereochemistry of the complex (shape)
Why is it important that a ligand splits the d-orbitals?
because then electrons from lower energy orbitals of the same subshell can absorb E and be promoted to a higher level orbital and reflect the complementary color from that which was absorbed (that’s why we see colors)
Spectrochemical series
how ligands are arranged according to their strength (ability to split orbitals – how far apart can they be split)
I− < Br− < S2− < Cl− < F− < OH− < H2O < SCN- < NH3 < CN− < CO
Intramolecular bonds types
bonds between atoms
1| Ionic bonding
2| Metallic bonding
3| Covalent bonding
Ionic bond
a chemical bond resulting from the transfer of electrons from a cation to an anion in an exothermic reaction – the energy released is called lattice energy – ionic bonding is the sum of all electrostatic reactions between oppositely charged ions
Characteristics of ionically bonded compounds
1| Crystalline at room temp
2| High melting and boiling points
3| Conductors in molten or solution state (not in solid)
4| Polar compounds
Metallic bonding, what does it strength depend on
electrostatic attraction between a lattice of positive metal ions and delocalized electrons
the number of delocalized electrons, and the charge and the ionic radius of metal ions.
Physical properties of metals
1| High melting point (decreases as the size of cations increases)
2| Malleable (can be beaten into shape)
3| Ductilie (can be drawn into a wire)
4| Electrical conductors (delocalized electrons)
Covalent bonding
chemical bonding resulting from the sharing of electrons between two bonding atoms (formed between two nonmetals) – can be single, double, or triple – electrons are not shared equally because of different electronegativities of different atoms
How does the difference in electronegativity determine the bond type
if the difference is more than 1.8, the bond is ionic, if it’s less than 1.8 but more than 0, it’s polar covalent, and if it is equal to 0 then it is non-polar (even distribution of charge)
Physical properties of covalent bonds
1| Definite and predictable shapes
2| Lower melting and boiling points
3| Generally insoluble in water
4| Nonconductors
Coordinate (dative) bonding
the electrons in a shared electron pair came from the same atom, e.g. (ligands) CO, NH4+, H3O+, SO2, SO3.
