To begin with...
A recap on subshells
Electron subshell recap
• Question: Write out the full electronic
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Electron subshell recap
• Question: Write out the full electronic
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Electron subshell recap
• Question: Write out the full electronic
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Electron subshell recap
• Question: Write out the full electronic
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si
Electron subshell recap
1s2
• Question: Write out the full electronic
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si 1s2
Electron subshell recap
1s2
2
• Question:
Write out the full electronic
2s
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si 1s2 2s2
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si 1s2 2s2 2p6
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
2
for the element: Si
3ssubshell
• 1s2 2s2 2p6 3s2 3p2
222s222p663s22
SiSi 1s
1s 2s 2p 3s
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
2
for the element: Si
3p2
3ssubshell
• 1s2 2s2 2p6 3s2 3p2
Si 1s2 2s2 2p6 3s2 3p2
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si 1s2 2s2 2p6
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si 1s2 2s2 2p6
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Si [Ne] 3s2 3p2
What about Cl-
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
for the element: Si
2
3ssubshell
3p5
• 1s2 2s2 2p6 3s2 3p2
Cl 1s2 2s2 2p63s23p5
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
for the element: Si
2
3ssubshell
• 1s2 2s2 2p6 3s2 3p2
Cl 1s2 2s2 2p63s23p5
• Its Cl-1
• Which means it has an extra electron!
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
for the element: Si
2
3ssubshell
• 1s2 2s2 2p6 3s2 3p2
Cl 1s2 2s2 2p63s23p5+1=6
Electron subshell recap
1s2
2
• Question:
Write out the full electronic2p6
2s
for the element: Si
2
3ssubshell
• 1s2 2s2 2p6 3s2 3p2
Cl 1s2 2s2 2p63s23p6
• Have a go at potassium
• And then K+1 (hint it has lost 1 electron).
Now attempt the worksheet...
Ions and metallic bonding
To be able to work out the charge on
different ions
To know the properties of metallic
bonding
Ions
• Ions are atoms or molecules that have lost or
gained electron(s).
• Positively charged ions are known as cations
– Just think, cats are great, really positive
• Negatively charged ions are called anions
– No one likes onions...
• Metals lose electrons to become positive
(cations)
• Non-metals gain electrons to become negative
(anions).
• If you see a Roman numeral after an element
it usually means how many electrons it has
lost.
• Transition metals can promote electrons
within sub shells to lose varying numbers of
electrons.
What charge will form?
• The easiest way to predict how many electrons
will be lost or gained is to use the periodic table.
• Group 1  lose 1 electron
• Group 2  lose 2 electrons
• Group 6  gain 2 electrons
• Group 7  gain 1 electron
• This is because atoms are looking to fill/empty
outer shells.
Quick task
• Can you predict how many electrons will be
lost or gained by the following elements?
–O
– Cl
– Al
– Br
– Na
– Ca
–H
– Fe?
• Have a go at the worksheet...
Electron subshell recap
• Question: Write out the full electronic
subshell for the element: Si
• 1s2 2s2 2p6 3s2 3p2
Metallic bonding
• Metals tend to have high melting points and boiling
points suggesting strong bonds between the atoms.
Even a metal like sodium (melting point 97.8°C) melts
at a considerably higher temperature than the element
(neon) which precedes it in the Periodic Table.
• The simplest description of the bonding in metals
consists of a lattice of metal cations in a sea of
delocalised electrons.
• A metal atom releases its outer electrons into the sea,
but its core electrons remain localised around its
nucleus. This extensive delocalisation of valence
electrons is responsible for most of the properties of
metals.
• There is an attraction between the positive
cations and the negative electrons.
• The more negative electrons in the outer shell
available to become delocalised, the stronger
the bonding.
• There the higher boiling point.
• Which metal has a higher boiling point,
sodium or magnesium?
• What happens as you go down the group?
• More shielding from inner shells, therefore
less of a positive charge to attract to the
delocalised electrons.
• Therefore weaker intermolecular bonding
• Therefore lower melting points.
Diagram...
Key definitions
• Metallic bonding: The electrostatic attraction
between positive metal ions and delocalised
electrons.