Covalent Bonding Flashcards
Covalent bond
A pair of electrons are shared between two atoms.
Simple molecular substances
Molecules containing a few atoms joined by covalent bonding
Covalent bond outlay
(atom)(atom)
Hydrogen
Hydrogen atoms have 1 electron, so they need 1 more to complete the first shell. Two hydrogen atoms each share the 1 electron they have to give the allusion that they both have 2.
Hydrogen Chloride (HCI)
Both atoms only need 1 more electron to complete their outer shell so they each share one.
Oxygen (O2)
Oxygen needs 2 electrons to complete their outer shell. Each oxygen forms a double covalent bond (a bond made of two shared electron pairs) with another oxygen atom.
Water (H2O)
An oxygen atom shares a pair of electrons with two hydrogen atoms to form a two Single covalent bonf
Properties
Simple molecular structure
Very strong bonds but forces of attraction between these molecules are weak
Low melting/boiling points-only need to break intermolecular forces not covalent bond
Gasses or liquids at room temperature
As molecule gets bigger = intermolecular forces increase =higher melting/boiling point
Don’t conduct electricity- no free electrons or ions
Some are soluble and some aren’t
Polymers
Molecules made up of long chains of covalently bonded carbon atoms
Diamond
A network of carbon atoms that each form four covalent bonds.
Strong covalent bonds =lots of energy to break =high melting point
Strong covalent bonds-holds atoms in a rigid lattice structure =very hard
Doesn’t conduct electricity- on free electrons or ions
Graphite
Each carbon atom only forms tree covalent bonds= sheets of carbon atoms arranged in hexagons
No covalent bonds between layers-held together weakly= layers are free to move over each other
High melting point- covalent bonds in layers needs lots of energy to break
Conducts electricity- each carbon atom has 1 delocalised (free) etectron
