1. Bell Work
Pass it clockwise to the next group – add or correct

2. Bell Work
Place post sticks on where you have any questions

3. Elements of the sea Big Picture Manufacturing Ions in solution
Ionic Formulae
Halogenoalkanes
Big Picture
Redox
Bonding
Atoms and Ions
Halogens
Dipoles
Elements of the sea

4. Learning Outcomes
Lets use your question post sticks to decide what we want to know

5. Which can you answer already?
What I already know
Which can you answer already?

6. CI3.1 Bonding continuum
Dative covalent – both bonding e- come from one atom – shown as  to demonstrate where e- from.

7. Polar bonds what are they?
A molecule or part of molecule (covalent) with a +ive and –ive end
δ + or – means there is unequal electron distribution
Between the two atoms
The polar bond in H-Cl
We say chlorine has greater electronegativity than hydrogen
Non-polar bonds
New Information 7

8. Electronegativity (Pauling scale)
New Information
Electronegativity (Pauling scale)
Ability to pull electrons in covalent bond 8

9. What causes electronegativity?
New Information
What causes electronegativity?
The attraction that a bonding pair of electrons feels for a particular nucleus depends on:
the number of protons in the nucleus (pull)
the distance from the nucleus
the amount of screening/shielding by inner electrons.
Ensure pupils know the magnetism is just an analogy. 9

10. Electronegativity New Information
Electronegativity is the ability of an atom to attract the bonding electrons In a covalent bond
Permanent dipole
Cl is more electronegative than hydrogen.
The same electronegativity.
Non polar
Polar
Bond polarisation means that the covalent bond has partial ionic character because it has a dipole moment (charge separation) 10

11. Polar bonds what are they?
New Information
Polar bonds what are they?
A polar bond is a bond with charge separation. It occurs in covalent molecules, and when it does we say there is a permanent dipole.
δ + or – means there is unequal electron distribution
Between the two atoms (tug of war)
The polar bond in H-Cl 11

12. Dipoles - permanent New Information
Occur when 2 bonded molecules have a substantial electronegativity difference.
Write & draw these molecule and decide whether they have a permanent dipole, and which the charge moves [18]
HCl CCl LiBr HF CO
Emphasis on only covalent – LiBr is ionic!! No dipole in CCl4 – as equal each other out 12

13. Electronegativity Pauling Scale
New Information
Electronegativity Pauling Scale 13

14. CI5.3 Dipoles - permanent New Information Covalent only!
δ + or – shown!
CH4 is symmetrical
C is 2.55 vs. H 2.20 therefore (:.) slightly polar
~ 0.5 difference needed for permanent dipole
+ Pauling scale is data based no absolutes δ
Emphasis on shape too – O=C=O (CO2) help to draw it out δ δ 14

15. Dipoles - permanent New Information
Charges can balance each other out, thus no overall charge on one side
Range of polarity
Dipoles leads to a “lop sidedness”
Average pictures only – e- moving!
Emphasis on shape too – O=C=O (CO2) help to draw it out 15

16. Temporary / Instantaneous Dipole
New Information
Temporary / Instantaneous Dipole
No dipole as same or very similar electronegativity i.e. Cl2
e-s are MOVING constantly, at one instant all e- around one side, causing an instantaneous/temporary dipole

17. Dipoles - permanent New Information
How does this polarised molecule affect molecules around it?
Around other permanent dipoles…..
Permanent dipole–permanent dipole (state both molecules)
Permanent dipole–dipole forces
between HCl molecules causes
this intermolecular bonding 17

18. Polarised molecule affect
New Information
Polarised molecule affect
Around unpolarised molecules…..
The permanent dipole attracts or repels e-s in charge cloud of unpolarised; INDUCING A dipole on it
Permanent dipole–induced dipole (state both molecules)
Unpolarised molecule
Turns into induced dipole near
permanent dipole 18

19. Polarised molecule affect
New Information
Polarised molecule affect
Inducing a dipole on an unpolarised molecule can also occur with an instantaneous (or temporary) dipole
Instantaneous dipole–induced dipole 19

20. Activity
Chemical Ideas 3.1
Start these .....

21. Where would you place dative covalent? Why?
Demonstrate
Where would you place dative covalent? Why?

22. Key word definition Review Electronegativity Dipole Polar
Dative covalent
Metallic
Induced dipole
Delta positive
Symmetrical

23. Home Learning
Finish CI 3.1