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Chemical Bonds. Attraction between two or more atoms Interaction between valence electrons Ionic bonds Covalent bonds. Valence Electrons. Electrons in the highest (outer) electron level Have most contact with other atoms Known as valence electrons

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chemical bonds
Chemical Bonds
  • Attraction between two or more atoms
  • Interaction between valence electrons
  • Ionic bonds
  • Covalent bonds

LecturePLUS Timberlake

valence electrons
Valence Electrons
  • Electrons in the highest (outer) electron level
  • Have most contact with other atoms
  • Known as valence electrons
  • Outer shelI of noble gases the outer shell contains 8 valence electrons as s2p6 (except He = 2)

Example: Ne 1s22s2 2p6

Ar 1s2 2s2 2p63s2 3p6

LecturePLUS Timberlake

electron dot structures
Electron Dot Structures

Symbols of atoms with dots to represent the valence-shell electrons

1A 2A 3A 4A 5A 6A 7A 8A

H He:

    

LiBe B  C  N  O : F : Ne :

     

    

Na Mg AlSiPS: Cl  : Ar :

   

LecturePLUS Timberlake

learning check b1
Learning Check B1

A. X would be the electron dot formula for

1) Na 2) K 3) Al

 

B.  X  would be the electron dot formula

1) B 2) N 3) P

LecturePLUS Timberlake

solution b1
Solution B1

A. X would be the electron dot formula for

1) Na 2) K

 

B.  X  would be the electron dot formula

2) N 3) P

LecturePLUS Timberlake

octet rule
Octet Rule
  • An octet in the outer shell makes atoms stable
  • Electrons are lost, gained or sharedto form an octet
  • Unpaired valence electrons strongly influence bonding

LecturePLUS Timberlake

formation of ions from metals
Formation of Ions from Metals
  • Ionic compounds result when metals react with nonmetals
  • Metals loseelectrons to match the number of valence electrons of their nearest noble gas
  • Positive ionsform when the number of electrons are less than the number of protons

Group 1A metals ion 1+

Group 2A metals ion 2+

  • Group 3A metals ion 3+

LecturePLUS Timberlake

formation of sodium ion
Formation of Sodium Ion

Sodium atom Sodium ion

Na  – e Na +

1s22s22p63s1 1s22s22p6 ( = Ne)

11 p+ 11 p+

11 e- 10 e-

01+

LecturePLUS Timberlake

formation of magnesium ions
Formation of Magnesium Ions

Magnesium atom Magnesium ion

Mg  – 2e Mg2+

1s22s22p63s2 1s22s22p6 (Ne)

12 p+ 12 p+

12 e- 10 e-

0 2+

LecturePLUS Timberlake

cations of some representative elements
Cations of Some Representative Elements

Group 1A Group 2A Group 3A

H+ Mg2+ Al3+

Li+ Ca2+

Na+ Sr2+

K+ Ba2+

LecturePLUS Timberlake

learning check b 2
Learning Check B 2

A. Number of valence electrons in aluminum

1) 1 e- 2) 2 e- 3) 3 e-

B. Change in electrons for octet

1) lose 3e- 2) gain 3 e- 3) gain 5 e-

C. Ionic charge of aluminum

1) 3- 2) 5- 3) 3+

LecturePLUS Timberlake

solution b 2
Solution B 2

A. Number of valence electrons in aluminum

3) 3 e-

B. Change in electrons for octet

1) lose 3e-

C. Ionic charge of aluminum

3) 3+

LecturePLUS Timberlake

learning check b 3
Learning Check B 3

Give the ionic charge for each of the following:

A. 12 p+ and 10 e-

1) 0 2) 2+ 3) 2-

B. 50p+ and 46 e-

1) 2+ 2) 4+ 3) 4-

C. 15 p+ and 18e-

2) 3+ 2) 3- 3) 5-

LecturePLUS Timberlake

solution b 3
Solution B 3

Give the ionic charge for each of the following:

A. 12 p+ and 10 e-

2) 2+

B. 50p+ and 46 e-

2) 4+

C. 15 p+ and 18e-

2) 3-

LecturePLUS Timberlake

learning check b 4
Learning Check B 4

A. Why does Ca form a Ca2+ ion?

B. Why does O form O2- ion?

LecturePLUS Timberlake

solution b 4
Solution B 4

A. Why does Ca form a Ca2+ ion?

Loses 2 electrons to give octet

1s2 2s2 2p6 3s2 3p6 4s2

1s2 2s2 2p6 3s2 3p6 (like Ar)

B. Why does O form O2- ion?

Gains 2 electrons to give octet

1s2 2s2 2p4 + 2e-

1s2 2s2 2p6 2-8 (like Ne)

LecturePLUS Timberlake

transition metals
Transition Metals
  • Loses electrons from the highest occupied energy level.
  • May also lose one or more d electrons.
  • Most form 2 or more positive ions

LecturePLUS Timberlake

fe 2 and fe 3
Fe2+ and Fe3+

Fe atom: 1s2 2s2 2p6 3s2 3p64s2 3d6

Loss of 4s2 electrons (outermost shell)

Fe2+ ion: 1s2 2s2 2p6 3s2 3p6 4s03d6

Loss of 3d1 electron

Fe3+ ion: 1s2 2s2 2p6 3s2 3p6 4s03d5

A 3d5 (half-filled) subshell is stable

LecturePLUS Timberlake

some transition metal ions
Some Transition Metal Ions

1+ 2+ 1+ or 2+ 2+ or 3+

Ag+ Cd2+ Cu+,Cu2+ Fe2+, Fe3+

silver cadmium copper(I) ion iron(II) ion

ion ion copper (II) ion iron(III) ion

Zn2+

zinc ion

LecturePLUS Timberlake

ions from nonmetal ions
Ions from Nonmetal Ions
  • In ionic compounds, nonmetals in 5A, 6A, and 7A gain electrons from metals
  • Nonmetal add electrons to achieve the octet arrangement
  • Nonmetal ionic charge:

3-, 2-, or 1-

LecturePLUS Timberlake

fluoride ions
Fluoride Ions

unpaired electron octet

1 -

: F  + e : F :



1s22s22p5 1s22s22p6 = Ne

LecturePLUS Timberlake

some nonmetal ions
Some Nonmetal Ions

5A 6A 7A

N3 O2 F

nitride __________ fluoride

P3 S2 Cl

___________ __________ _________

Br 

_________

I

iodide ion

LecturePLUS Timberlake

some nonmetal ions1
Some Nonmetal Ions

5A 6A 7A

N3 O2 F

nitride oxide fluoride

P3 S2 Cl

phosphidesulfidechloride

Br 

bromide

LecturePLUS Timberlake

ionic compounds
Ionic Compounds
  • Attraction between + ions and - ions
  • Electrons go from metals to nonmetals

electron transfer

metal nonmetal ion+ ion-–

Electrons lost = Electrons gain

LecturePLUS Timberlake

formulas of ionic compounds
Formulas of Ionic Compounds

Formulas of ionic compounds are determined from the charges on the ions

atoms ions

 –

Na  +  F :  Na+ : F :  NaF



sodium fluorine sodium fluoride formula

Charge balance: 1+1- = 0

LecturePLUS Timberlake

writing a formula
Writing a Formula

Write the formula for the ionic compound that will form between Ba2+ and Cl.

Solution:

1. Balance charge with + and – ions

2. Write the positive ion of metal first, and the

negative ion Ba2+ ClCl

3. Write the number of ions needed as

subscriptsBaCl2

LecturePLUS Timberlake

learning check b 5
Learning Check B 5

A. The formula for the ionic compound of

Na+ and O2- is

1) NaO 2) Na2O 3) NaO2

B. The formula of a compound of aluminum and chlorine is

1) Al3Cl 2) AlCl2 3) AlCl3

C. The formula of Fe3+ and O2- is

1) Fe3O2 2) FeO3 3) Fe2O3

LecturePLUS Timberlake

solution b 5
Solution B 5

A. The formula for the ionic compound of

Na+ and O2- is

2) Na2O

B. The formula of a compound of aluminum and chlorine is

3) AlCl3

C. The formula of Fe3+ and O2- is

3) Fe2O3

LecturePLUS Timberlake