4. Covalent bonding Flashcards
Why do elements take part in reactions?
- To achieve a full outer shell
- To achieve a stable electron arrangement
- To achieve a noble gas electron arrangement
How do non-metal atoms achieve a full outer shell when they react with one another?
They share unpaired electrons.
What is a covalent bond?
A shared pair of electrons
What holds the atoms together when they form covalent bonds?
The common (electrostatic) attraction the nuclei have for the shared pair of electrons.
What is a molecule?
2 or more atoms joined by covalent bond(s)
What do we call the attractions between molecules?
Intermolecular attractions
Are intermolecular bonds strong or weak?
Weak
What happens when we melt or boil substances composed of molecules?
We break the weak intermolecular attractions
What is an orbital diagram?
Normally 4 lobes as shown in diagram with ONLY the outer electrons shown. it shows the arrangement of ALL outer electrons in the molecule
The diagram is for a Cl atom
What is meant by valency?
The number of unpaired electrons an atom has in its outer (valence) shell.
In the example shown for Cl , only 1 electron is unpaired so the valency is 1
Why do covalent compounds not conduct electricity:?
Because the molecules or networks do not carry any overall charge.
The total number of protons and electrons are equal
Why do covalent network substances have high melting points?
Because you have to break a lot of strong covalent bonds.
Why do covalent molecular substances have low melting and boiling points?
Because you only have to break weak intermolecular attractions
What type of bonding is shown in the diagram?
Covalent molecular
What type of bonding is shown?
Covalent network
Name the 7 diatomic covalent molecular elements
Iodine
Hydrogen
Nitrogen
Bromine
Oxygen
Chlorine
Fluorine
Which shape do all diatomic molecules have:?
Linear
Which shape does water have?
Angular
Which shape does ammonia (Nitrogen hydride) have?
Trigonal Pyrimidal
Which shape does Methane have?
Tetrahedral
