What is ionic bonding?
Ionic bonding involves an attraction between oppositely charged ions.
Where are ionic bonds found?
Found in compounds made from metal and non-metals.
What is covalent bonding?
Covalent bonding involves 2 atoms sharing one or more pairs of electrons.
Where are covalent bonds found?
Found in most non-metal elements and in compounds of non-metals.
What is metallic bonding?
Metallic bonding involves an attraction between positively charged ions and negatively charged delocalised electrons.
Where are metallic bonds found?
Found in metals and alloys (mixtures of metals and other substances).
How many types of chemical bond are there and name these:
3: Covalent, metallic and ionic.
Which type of bonding happens in most non-metal elements?
What are ions?
Ion are charged particles. They are created when an atom or molecule gains or loses electrons.
How are ions created?
Gaining electrons creates a negatively charged ion; losing electrons creates a positively charged ion.
How are positive ions created?
Usually created when an atom or molecule loses electrons.
What can positive ions also be called?
The metals in group 1 and 2 can easily lose..
…electrons to become positively charged ions.
How are negative ions created?
When an atom or molecule gains electrons.
What are negative ions also called?
The non-metals in group 7 are most likely to…
…gain electrons to fill up their electrons shell and become negatively charged.
Ions can be:
Single elements (eg F-) A group of element with an overall charge (eg SO42-)
How does the nucleus of an atom change when it gains electrons?
Positive ions are usually made when an atom or molecule…
What happens when atoms form ions?
They try to fill up or empty their outer electron shell.
How do group 1 metals form ions?
Always lose 1 electron to form positive ions with a charge of +1.
How do group 2 metals form ions?
Always lose 2 electrons to form doubly positive ions.
How do non-metals form ions (groups 6 and 7)?
Always gain electrons to form (become) negative ions.
How do noble gases (group 0) form ions?
Already have a full outer shell so are unreactive and don’t normally form ionic bonds with other elements.
Materials with ionic bonds usually…
Only conduct electricity when molten/dissolved.
Have high melting points.
Sodium is in group 1 and oxygen is in group 6. In the dot-and-cross diagram for sodium oxide, how many sodium ions would there be?
Through which diagram can we show the transfer of electrons and ions formed?
Dot and cross diagrams.
What is an ionic compound?
When millions of metal atoms transfer their outer electrons to millions of non-metal atoms at the same time, resulting in oppositely charged ions held together in ionic lattices.
What is an ionic lattice?
Giant structures that are held together by strong electrostatic forces between oppositely charged ions.
What are electrostatic forces?
Called ionic bonds that extend in all directions within the lattice.
What does an empirical formulae help us to do?
Helps us to work out the proportion of each ion in a compound and is the simplest ratio of ions possible of an ionic compound.
What is the empirical formulae of Ca2+ and F- ions?
In order for the charges to balance out and for the overall formula to be neutral, there must be 2 F- ions for each Ca2+ ion.
The empirical formula is CaF2.
Facts about ionic lattices…
Held together by electrostatic forces.
Contain negatively charged non-metal ions.
Contain positively charged metal ions.
Why are Covalent bonds strong?
Because the shared electrons are attracted to the nucleus of both atoms.
Covalently bonded substance can be:
Small molecules (water) Large molecules (such as polyester and silk) Giant covalent structures (diamond)
Describe the structure of an metal:
Giant structures of regularly arranged electrons. A regular lattice of cations in a ‘sea’ of delocalised electrons.
What are delocalised electrons?
Not bound to an atom and are free to move around the lattice.
Why does delocalisation happen?
Metal atoms have a smaller amount of electrons in their outer shells.