1. תרכובות קוולנטיות קשרים קוולנטים
Covalent bonds form when atoms of nonmetals share electrons to complete octets.
Valence electrons are not transferred, but shared to achieve stability.
between nonmetal atoms from Groups 4A(14), 5A(15), 6A(16), and 7A(17).

2. H2 יצירת In the simplest covalent molecule, H2 , the H atoms
increase attraction as they move closer.
share electrons to achieve a stable configuration.
form a covalent bond.

3. H2יצירת
A covalent bond forms as H atoms move close together to share electrons.

4. מבנה לואיס מציג את אלקטרוני הערכיות וזוגות האלקטרונים המשותפים
A hydrogen molecule
is stable with two electrons (like helium).
has a shared pair of electrons.

5. Electron-Dot Formulas of Covalent Molecules
In a fluorine (F2) molecule, the F atoms
share one of their valence electrons.
acquire an octet.
form a covalent bond.

6. יסודות הקיימים כמולקולות דו-אטומיות
These seven elements share electrons to form diatomic, covalent molecules.

7. תרגיל
Learning Check
What is the name of each of the following diatomic molecules?
H2 _______________
N2 _______________
Cl2 _______________
O2 _______________
I2 _______________

8. פתרון
Solution
What is the name of each of the following diatomic molecules?
H2 hydrogen
N2 nitrogen
Cl2 chlorine
O2 oxygen
I2 iodine

9. מספר קשרים קוולנטים היוצרים אטומים
The number of covalent bonds a nonmetal forms is usually equal to the number of electrons it needs to acquire a stable electron configuration.
Typical bonding patterns for some nonmetals are shown in the table below.

10. Carbon forms 4 covalent bonds
CH4 מבנה לואיס של
Carbon forms 4 covalent bonds
In a CH4, methane, molecule
a C atom shares 4 electrons to attain an octet.
each H shares 1 electron to become stable like helium.

11. Writing Electron-Dot Formulas
CH4 רישום מבנה לואיס של
Writing Electron-Dot Formulas
To draw the electron-dot formula for methane, CH4,
we start with the electron-dot symbols for carbon and hydrogen
we need four hydrogen atoms to complete carbon’s octet
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

12. דוגמא- מבני לואיס של תרכובות קוולנטיות

13. Exceptions to the Octet Rule
יוצאי דופן לכלל האוקטט
Exceptions to the Octet Rule
Not all atoms have octets.
Some can have less than an octet, such as
H, which requires only 2 electrons,
B, which requires only 6 electrons, and
Some can have expanded octets, such as
P, which can have 10 electrons,
S, which can have 12 electrons, and
Cl, Br and I, which can have 14 electrons

14. Single and Multiple Bonds
קשרים קוולנטים מרובים
Single and Multiple Bonds
In many covalent compounds, atoms share two or
three pairs of electrons to complete their octets.
In a single bond, one pair of electrons is shared.
In a double bond, two pairs of electrons are shared.
In a triple bond, three pairs of electrons are shared.

15. Double and Triple Covalent Bonds
המשך
Double and Triple Covalent Bonds
A double bond:
occurs when atoms share two pairs of electrons
forms when there are not enough electrons to complete octets
A triple bond:
occurs when atoms share three pairs of electrons
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

16. Material from karentimberlake.com and
מולקולת חמצן בעלת קשר כפול
Double Covalent Bond
2 pairs of electrons are shared between 2 atoms
Example O2
       
 O   O   O::O
double bond
Material from karentimberlake.com and
H. Stephen Stoker

17. Electron-Dot Formulas for Some Covalent Compounds – CO2
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

18. מולקולת חנקן בעלת קשר משולש
In a nitrogen molecule, N2,
each N atom shares 3 electrons,
each N atom attains an octet, and
the sharing of 3 sets of electrons is called a triple bond.

19. Material from karentimberlake.com and
Triple Covalent Bond
3 pairs of electrons are shared between 2 atoms
Example N2
       
 N   N   N:::N
 
triple bond
Material from karentimberlake.com and
H. Stephen Stoker

20. מבני רזוננס Resonance structures are
two or more electron-dot formulas for the same arrangement of atoms.
related by a double-headed arrow ( ).
written by changing the location of a double bond between the central atom and a different attached atom.

21. SO2 דוגמא - מבני רזוננס של
Because the shared lone pair of electrons can come from either O atom, two resonance structures can be drawn.

22. שלבים ברישום מבנה לואיס
נושא זה הוא הרחבה

23. NH3 א. שלבים ברישום מבנה לואיס של
Step 1 Determine the arrangement of atoms.
In NH3, N is the central atom and is bonded to
three H atoms.
Step 2 Determine the total number
of valence electrons.
Total valence electrons for NH3 = 8 e−

24. המשך Step 3 Attach each bonded atom to the central
atom with a pair of electrons.

25. המשך Step 4 Place the remaining electrons using single
or multiple bonds to complete the octets.
8 valence e− − 6 bonding e− = 2 e− remaining
Use the remaining 2 e− to complete the octet
around the N atom.

26. תרגיל
Learning Check
Draw the electron-dot formula for CCl4.

27. Solution פתרון Step 1 Determine the arrangement of atoms.
In CCl4, C is the central atom and is bonded to
four Cl atoms.

28. Solution המשך Step 2 Determine the total number of valence electrons.
Total valence electrons for

29. Solution המשך Step 3 Attach each bonded atom to the central
atom with a pair of electrons.

30. Solution המשך Step 4 Place the remaining electrons, using single
or multiple bonds to complete the octets.
32 valence e− − 8 bonding e− = 24 e− remaining
Use the remaining 24 e− to complete the octets
around the Cl atoms.

31. CS2 דוגמא ב: רישום מבנה לואיס של
Step 1 Determine the arrangement of atoms.
In CS2, C is the central atom and is bonded to
two S atoms.

32. המשך Step 2 Determine the total number of valence electrons.
Total valence electrons for

33. המשך Step 3 Attach each bonded atom to the central
atom with a pair of electrons.
A pair of bonding electrons (single bond) is
placed between each S atom and the central C
atom.

34. המשך Step 4 Place the remaining electrons using single
or multiple bonds to complete the octets.
16 valence e− - 4 bonding e− = 12 e− remaining
The remaining 12 electrons are placed as six
lone pairs of electrons on both S atoms.
However, this does not complete the octet for
the C atom.

35. המשך Step 4 Continued: Double and Triple Covalent
Bonds: To complete the octet for the C atom, it needs to share an additional lone pair from each of the S atoms, forming a double bond with each S atom.

36. Electron-Dot Formulas for Some Covalent Compounds – CO2
Step 1 Determine the arrangement of atoms. O C O
Step 2 Determine the total number of valence electrons.
C 2(O) = CO2
4e− + 2(6−) = 16e−
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

37. CO2 המשך דוגמא ג: רישום מבנה לואיס של
Step 3 Attach each bonded atom to the central atom
with a pair of electrons.
Step 4 Place the remaining electrons using single or
multiple bonds to complete octets.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

38. מבני רזוננס Resonance structures are
two or more electron-dot formulas for the same arrangement of atoms.
related by a double-headed arrow ( ).
written by changing the location of a double bond between the central atom and a different attached atom.

39. מבני רזוננס של SO2 רישום מבני רזוננס של
Sulfur dioxide has two resonance structures.
Step 1 Determine the arrangement of atoms. In SO2,
the S atom is the central atom.
O S O
Step 2 Determine the total number of valence
electrons.
Total valence electrons for

40. המשך
Step 3 Attach each bonded atom to the central atom with a pair of electrons. O S o r

41. המשך Step 4 Place the remaining electrons using single
or multiple bonds to complete the octets.
The remaining 14 electrons are drawn as lone
pairs of electrons to complete the octets of the
O atoms, but not the S atom.

42. המשך Step 4 Continued: To complete the octet for S, an
additional lone pair from one of the O atoms
is shared to form a double bond.
Because the shared lone pair of electrons can
come from either O atom, two resonance
structures can be drawn.

43. תרגיל
Learning Check
FNO2, a rocket propellant, has two resonance structures. One is shown below. What is the other resonance structure?

44. פתרון
Solution
FNO2, a rocket propellant, has two resonance structures. One is shown below. What is the other resonance structure?

45. Naming Covalent Compounds
מינוח של תרכובות קוולנטיות
Naming Covalent Compounds
To name covalent compounds
STEP 1: Name the first nonmetal as an element.
STEP 2: Name the second nonmetal with an ide ending.
STEP 3: Use prefixes to indicate the number of atoms (subscript) of each element.
Table4.12

46. דוגמא What is the name of SO3? 1. The first nonmetal is S sulfur.
2. The second nonmetal is O named oxide.
3. The subscript 3 of O is shown as the prefix tri.
SO3  sulfur trioxide
The subscript 1 (for S) or mono is understood.

47. נוסחאות ודוגמאות של תרכובות קוולנטיות
N2O dinitrogen oxide Inhalation anesthetic’ “ laughing gas”

48. נוסחאות ודוגמאות של תרכובות קוולנטיות
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

49. Learning Check Select the correct name for each compound.
A. SiCl4 1) silicon chloride
2) tetrasilicon chloride
3) silicon tetrachloride
B. P2O5 1) phosphorus oxide
2) phosphorus pentoxide
3) diphosphorus pentoxide
C. Cl2O7 1) dichlorine heptoxide
2) dichlorine oxide
3) chlorine heptoxide

50. Name the following compounds
A. Ca3(PO4)2
ionic Ca2+ PO43− calcium phosphate
FeBr3
ionic Fe3+ Br − iron(III) bromide
SCl2
covalent 1S 2 Cl sulfur dichloride
Cl2O
covalent 2 Cl 1 O dichlorine monoxide

51. Write the formulas for the following:
calcium nitrate
Ca2+, NO3− Ca(NO3)2
boron trifluoride
1 B, 3 F BF3
aluminum carbonate
Al3+, CO32− Al2(CO3) 3
dinitrogen tetroxide
2 N, 4 O N2O4

52. Summary to Naming Simple Compounds
סיכום מינוח תרכובות יוניות ותרכובות קוולנטיות
Summary to Naming Simple Compounds
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.