1. 8.10 – Types of Bonds
Chemical bond: force that holds atoms together to form molecules, the attraction between electrons of one atom to the nucleus of another atom
The nature of the bond (degree of electron sharing) can be predicted using electronegativity

2. F Electronegativity: an atom’s ability to attract electrons e-
I got cookies F e-

4. What happens when two atoms of the same element form a bond?
No need to fight over us! We find you both equally attractive! HA HB e- e-
2.1
2.1

5. Covalent bonds occur between 2 non metals that have an electronegativity difference of ≤ 0.2
Equal sharing of electrons
a pair of electrons is simultaneously attracted to two nuclei  two atoms share the bonding electrons
atoms will try to get full outer shells

6. 1 2.1 – 2.1 = 0 Example: hydrogen gas H2
How many bonds are there? ______(___________)
Difference in electronegativity between the two atoms: _________________
single bond
2.1 – 2.1 = 0

7. Example: oxygen gas O2
3.5
3.5 2
How many bonds are there? _____ (_____________)
Difference in electronegativity= _________________
double bond
3.5 – 3.5 = 0

8. How many electrons will be shared in a triple bond?6

9. H Cl e- What happens when two different atoms form a bond? 2.1 3.0
Sorry H… but Cl is more attractive than you H Cl e-
2.1
3.0

10. Polar covalent bonds occur between 2 non-metals that have an electronegativity difference of 0.3 – 1.6
Unequal sharing of electrons
a pair of electrons is shared, but they are more attracted to one nuclei than the other resulting in a __________________
dipole

11. .. d+ d- H : Cl : .. Example: HCl
Let’s just look at the pair of electrons that are shared between H and Cl
Electrons are more attracted to Cl because Cl has a higher electronegativity
H becomes __________________________
Cl becomes __________________________ ..
d d-
H : Cl : ..
3.0 – 2.1 = 0.9
partially positively charged
partially negatively charged

12. Example: H2O
Again, let’s just look at the pair of electrons that are shared between H and O
H becomes _______________________
O becomes _______________________
3.5 – 2.1 = 1.4 d+ d+
H H O d-
partially positively charged
partially negatively charged

13. What happens when two atoms of very different electronegativities form a bond?

15. Ionic bonds occur between a metal and non-metal that have an electronegativity difference of > 1.6
No electron sharing, involves electron transfer 1+ 2+ 2- 1-
2+, 3+, 4+

16. Ionic bonds occur between a metal and non-metal that have an electronegativity difference of > 1.6
No electron sharing, involves electron transfer
Metal atom (or the atom with lower electronegativity) gains electrons and becomes positively charged  cation
Non-metal atom (or atom with the higher electronegativity) gains electrons and becomes negatively charged  anion
Atoms are held together by ___________________

17. Atoms bonded covalently are held together by the sharing of electrons.
No electron sharing occurs in ionic bonds.
What is holding the two atoms together in an ionic bond?

18. Ionic bonds occur between a metal and non-metal that have an electronegativity difference of > 1.6
No electron sharing, involves electron transfer
Metal atom (or the atom with lower electronegativity) gains electrons and becomes positively charged  cation
Non-metal atom (or atom with the higher electronegativity) gains electrons and becomes negatively charged  anion
Atoms are held together by ___________________
electrostatic charge

19. Example: NaF Difference in electronegativity between two atoms:
4.0 – 0.9 = 3.1