5.3 Covalent bonding Flashcards
What is covalent bonding
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
Where does covalent bonding occur
non-metallic elements, eg. H2 and O2
Compounds of non-metallic elements, for example H2O and CO2
Polyatomic ions for example NH4+
What units can form by covalent bonds
Small molecule - eg. H2
Giant covalent structure - eg. SiO2
Charged polyatomic ion - eg. NH4+
What is a covalent bond
An overlap of atomic orbitals each containing one electron to give a shared pair of electrons
Attraction is LOCALISED
How does a covalent bond , bond
The shared pair of electrons is attracted to the nuclei of both the bonding atoms
The bonding atoms often have outer shells with the same electron structure as the nearest noble gas
What is a molecule
The smallest part of a covalent compound that can exist while retaining the chemical properties of the compound
Difference between ionic and covalent bonding
In covalent bonding, electrons are shared but in ionic bonding, the electrons are transferred
What does the displayed formula show
The relative positioning of atoms and the bonds between them as lines
Ione pairs can also be added - eg. in H2O
What are Ione pairs
Paired electrons that are not shared
How many bonds are formed by carbon
4
How many bonds are formed by nitrogen
3
How many bonds are formed by oxygen
2
How many bonds are formed by hydrogen
1
When can ‘expansion of the octet’ take place
Only from the n=3 shell when a d-sub shell becomes available for the expansion
Example is sulfur hexafluoride
When does a multiple covalent bond exist
When two atoms share more than one pair of electrons