1. Chapter 6 Section 1 - 4
Chemical Bonding

2. Chemical Bond…
A mutual __________ attraction between the _________ and __________________ of different atoms that binds the atoms together.
Most atoms are at a __________ energy state when bonded to other atoms rather than as independent particles

3. Types of chemical bonds:
Covalent
Covalent-network
Ionic
Metallic

4. Ionic bonding
Results from the ____________ attraction
between large numbers of _______ (+ ions)
and ___________ (- ions)
Covalent bonding Results from the ____________ of electron pairs between 2 atoms

5. Ionic Bonding Δ electronegativity > ________
_____________ differences in electronegativity values between atoms:
One atom attracts an e- so strongly that it actually PULLS IT AWAY from the other atom…electron is _______________
Δ electronegativity > ________

6. Nonpolar Covalent Bond
Bonding electrons are shared ____________ by the bonded atoms, resulting in a balanced distribution of electrical charge
Δ electronegativity: ____________ (roughly)

7. Polar-covalent bond
Bonding electrons are shared ____________ because one atom pulls, although not very strongly, more on the electron pair than the other atom
Δ electronegativity: ______________
Still relatively small differences, so no atom really “wins” & e- is shared

8. Why would nature favor forming a covalent bond?

9. Attraction: nucleus of one atom to ______________
Repulsion: both _____ repel…as do both _________
As atoms approach, ____________ increases and potential E goes down
Beyond a certain point, ________________increases and E goes up
∴ bottom of valley on E curve is where there is a _______ between attraction & repulsion

10. MOLECULE: neutral group of atoms held together by _________________ bonds
MOLECULAR COMPOUND: a cmpd that is made of molecules
MOLECULAR FORMULA: shows the _____________ & ______________ of atoms making up a molecule i.e. H2O
DIATOMIC MOLECULE: molecule containing only ________ atoms i.e. H2

11. Characteristics of the Covalent Bond
Bond Length: average distance between 2 bonded atoms (min potential E)
In the H2 molecule, the 1s orbitals overlap and result in a increased electron density between the nuclei.

13. Bond energy:
Energy required to ___________ a chemical bond and form neutral isolated atoms
Measured in __________________
________ value
Bond energy and bond length values will vary depending on what atoms an element is bonded to…ave values found on tables P.168)

14. Octet Rule
Chemical cmpds tend to form so that each atom, by gaining, losing or sharing electrons, has an ________________ of electrons in its highest (outermost) energy level
Example of exceptions:
H: only has 2 valence e-s required to reach stability
B: only has 6 valence e-s “ “
Some elements have > 8 (occurs when atom bonds with highly electroneg elements & some “d” e-s are involved in bonding

15. Electron Dot Diagrams
Electron configuration notation in which only the valence electrons of an atom of a particular element are shown, indicated by dots placed around the element’s symbol F:

17. “other” dot diagram format
Mg: [Ne]3s2
“paired” electrons are shown as a pair

18. Lewis Structures Formulas in which….
atomic symbols are represent ___________________________________
Dot-pairs or dashed between 2 atoms represent _____________________________
Dots adjacent to only one atomic symbol represent _____________________________

19. Lewis structure
Structural Formula: indicates the kind, number, arrangement,and bonds .. but NOT the unshared
pairs of the atoms in a molecule

20. Lewis structure
Single bond: covalent bond produced by the sharing on ONE pair of electrons between 2 atoms

21. Draw the Lewis structure for the following molecules:
IBr
CH3Br
F2O
SiCl4
C2HCl (????)

22. Multiple Covalent Bonds
DOUBLE BOND
sharing of ___ pairs of electrons between 2 atoms
TRIPLE BOND
sharing of _____ pairs of electrons between 2 atoms
Bond Energies
triple double single
…..triple bonds are _________ and _______

23. Resonance Structures
bonding in molecules or ions that cannot be correctly represented by a single Lewis structure

24. Covalent-network Bonding
Covalent bonding exists
throughout a large network
of atoms…will be
discussed in chapter 12
i.e. carbon atoms
in a diamond

25. Ionic Compound
composed of positive and negative ions that are combined so that the number of positive charges are equal to (cancel out) the number of negative charges
Na+1Cl-1
Mg+2Cl (Mg+2Cl-1Cl-1)
Not called “molecules”…but called _____________________________

26. Formation of Ionic Cmpds
Atoms form ions when they ______________ e- in order to attain _________________________
Ions reach a ____________ potential E through the electrical forces of attraction between oppositely charged particles when they combine in an orderly arrangement known as a _____________
Forces of repulsion (like-charged ions, adjacent e- clouds) _____________ the forces of attraction (opp-charged ions, nuclei-electron of adj. ions)

27. Sodium chloride, NaCl
The chemical formula of an ionic cmpd is the simplest formula of the cmpd…it does NOT represent a discrete GROUP of separate atoms like a molecule does
Covalent bonding: simplest unit is a ________________
Ionic bonding: simples unit is a _________________________

28. “belong” to any one neighbor
“Molecules” – discrete gps of atoms covalently bonded
“Formula units” –
simplest collection
of atoms within an
ionic cmpd
i.e. NaCl..Na+1 doesn’t
“belong” to any one neighbor

29. Lattice Energy Term used to describe ___________ in ionic cmpds
Energy ____________________ when one of an ionic crystalline cmpd is formed from gaseous ions
_________ value indicates that E is ________
The __________ the value, the more E released, the more stable the bonding will be (true also for bond E)
i.e. NaCl –787.5 kJ/mol

30. Which ionic cmpd has a higher melting point….MgO or CaO ?

31. Ionic vs. Covalent Properties
strong force that holds _________________
stronger forces of attraction _____________ ions
∴_________ melting & boiling pts; don’t vaporize at room temp
MOLECULAR
strong covalent bond ____________________________________
_______ F of attraction ___________ molecules
∴melt at __________ temps & many vaporize at room temp

32. Other ionic properties…
________________: tough for one layer to slide past
another layer
______________: if ionic layers DO shift, they “snap” when part of their crystal lattice is shifted

33. Ionic vs. Covalent Properties
non-conductors in solid state because _________________
conductors in ______________ state
conductors when _________________
MOLECULAR
non-conductors in ________________

34. Polyatomic Ions A ______________ group of ____________ bonded atoms
Combine with ions of opposite charge to form __________________ cmpds

35. Draw the Lewis structure for the phosphate ion

36. Metallic Bond Model
Metals have _______________ electrons in their highest E level
Metals frequently have many _________________________________
Vacant orbitals of adjacent atoms overlap which allows _________________________________

37. Metallic Bond Model (con’t)
“_________________ electrons” - e-s don’t stay in one locality like…
covalent bonding: stay in the ________________________________
Ionic bonding: e-s are bound to ________________________________
mobile electrons form a “________ of electrons”

38. Metallic Bonding
the chemical bonding that results from the attraction between ___________________________________
______________ sharing of many e-s where each atom contributes its valence e-s which are then free to move about the mostly vacant outer orbitals of all the metal atoms

39. Metallic Properties __________ electrical & thermal conductivity
due to high mobility and delocalization of e-s
_____________ (shine)
metals absorb E and become “excited” very easily because many of their orbitals are separated by extremely small ∆E…shine occurs when photons are emitted when excited e-s return to ground state

40. Metallic Prop. (con’t)
_______________________ (ability to be hammered/beaten into thin sheets) and ____________________ (ability to be drawn, pulled, or extruded to produce wire) because metallic bonding is the same in all directions and a shift in layers of atoms is inconsequential

41. Metallic Bond Strength
Expressed in the _________________ value where the bonded atoms in the metallic solid state are converted into ___________________ metal atoms in the gaseous state (usually↑heat of vap, the ____ the bond strength)
Determined by
___________________________________