Covalent Bonding Flashcards
Define covalent bonding.
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
What does covalent bonding occur between?
Non-metallic elements
Compounds of non-metallic elements
Polyatomic ions
What is the key feature of covalent bonding?
The sharing of a pair of electrons between two atoms.
In what three ways are the atoms in a covalent bond bonded together?
In a small molecule
A giant covalent structure
A charged polyatomic ion
What is a covalent bond the overlap of?
It is the overlap of atomic orbitals.
What is the shared pair of electrons attracted to?
The nucleus of both the bonding atoms.
What type of electron structure do the outer shells of the bonded atoms have?
The bonded atoms often have outer shells with the same electron structure as the nearest noble gas.
What is the attraction like in covalent bonds?
It is localised.
What is meant by a localised bond?
This is an attraction at acts solely between the shared pair of electrons and the nuclei of the two bonded atoms.
What is a result of localised attraction?
A molecule.
What is a molecule?
This is the smallest part of a covalent compound that can exist whilst retaining the chemical properties of the compound.
What is the difference between ionic and covalent bonding?
In covalent bonding electrons are shared.
In ionic bonding electrons are transferred.
What is a displayed formula?
This is a formula that shows the relative position of atoms and the bonds between them.
What do the lines in displayed formulae represent?
Bonds
How are lone pairs presented in displayed formulae?
As dots (..).
What is a lone pair?
These are any pairs of electrons that are not shared.
Which molecule shows that predictions for bonding cannot be based solely on the noble gas electron structure?
BF3
What is expansion of the octet?
This is where the outer shell electron configuration is different to that of the nearest noble gas because more electrons are in the outer shell.
From which shell is expansion of the octet possible?
N=3
When can multiple covalent bonds exist?
When two atoms share more than one pair of electrons.
What is the electrostatic attraction between in a double bond?
It is between two shared pairs of electrons and the nuclei of the bonding atoms.
What is the electrostatic attraction between in a triple covalent bond?
The electrostatic attraction is between the three shared pairs of electrons and the nuclei of the bonding atoms.
What is a dative covalent bond?
This is a bond in which the shared pair of electrons has been supplied by one of the bonding atoms only.
What is another word for a dative covalent bond?
Coordinate bond.
In a dot and cross diagram, what is used to show a dative covalent bond?
An arrow
In which direction does the arrow showing the dative covalent bond point?
It points towards the atom that didn’t share electrons.
What is meant by the term average bond enthalpy?
This is a measurement of covalent bond strength.
What happens as the average bond enthalpy increases?
The covalent bond gets stronger.
