2.2 Electrons, Bonding and Structure Flashcards
What is an orbital?
A region of around the nucleus that can hold up to two electrons, with opposite spins.
How many electrons in an s-orbital?
2
How many electrons in p-orbitals?
6
How many electrons in d-orbitals?
10
How many electrons in f-orbitals?
14
What is electronegativity?
The ability of an atom to attract the bonding electrons in a covalent bond.
What is the principal quantum number?
It represents the overall energy of each orbital
What is an ionic bond?
An electrostatic attraction between two oppositely charged ions.
Define covalent bond.
The strong electrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms.
Which covalent compounds are special.
Boron trifluoride and sulphur hexafluoride.
What is average bond elthalpy?
The energy required to break a covalent bond
What is dative covalent bonding?
Where both electrons come from one atom.
Angle of linear molecules.
180
Angle of trigonal planar
120
Angle of tetrahedral
109.5
Angle of trigonal pyramidal
107
And of nonlinear
104.5
Angle of trigonal bipyramidal (five electron pairs)
120 and 90
And of octahedral.
90
What is electronegativity?
An atoms ability to attract an electron pair in a covalent bond
Most electronegative elements in order.
F, O, Cl, N, C, H
What is a dipole?
A difference in charge between two atoms caused by a shift in the electron density of the bond.
What does the Pauling scale measure?
Electronegativity of an atom.
What is a dative covalent bond?
A shared pair of electrons
Where both electrons are donated by one atom
How does the number of election pairs allow us to predict bond shape?
Pairs of electrons surround a central atom repel
Shape is determined by the number of bond pairs
AND
The number of lone pairs
What are the two types of intermolecular force?
hydrogen bonding
Van der Waals forces
What do Van der Waals forces include?
- permanent dipole -induced dipole
- permanent dipole - permanent dipole
- london (dispersion) forces
How do permanent induced dipoles arise?
molecule with permanent dipole causes non polar molecule to become slightly charged and attracts it
What are London (dispersion) forces?
- two non-polar
-instantaneous dipoles formed due to random movement of electrons
induces dipoles in neighbouring molecules
What does the size of London forces depend on?
increases with increasing numbers of electrons
Example of giant covalent lattices
diamond
graphite
SiO2
Are giant covalent lattices soluble?
no
What molecules have hydrogen bonding?
N O F
