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Chemical Bonds. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons. Gain 4 electrons. C would like to N would like to O would like to. Gain 3 electrons. Gain 2 electrons. Electron Dot Structures.

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Presentation Transcript
slide2

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

Gain 4 electrons

  • C would like to
  • N would like to
  • O would like to

Gain 3 electrons

Gain 2 electrons

electron dot structures
Electron Dot Structures

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

1 2 13 14 15 16 17 18

H He:

    

LiBe B  C  N  O : F :Ne :

     

    

Na Mg AlSiPS:Cl  :Ar :

   

chemical bond
Chemical bond
  • A chemical bond forms when outer-shell electrons of different atoms come close enough to each other to interact and rearrange themselves into a more stable arrangement.
types of chemical bonds
Types of Chemical Bonds
  • Ionic bonds formed when metal atoms combined with non-metal atoms

• Metallic bonds formed when metal atoms combined with metal atoms.

• Covalent bonds formed when non-metal atoms combined with non-metal atoms.

slide9

1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

slide10

The coordination number of an ionic lattice is written

as a ratio x:y

How many chlorine ions surround

each sodium ion and vice versa?

NaCl coordination number- 6:6

hardness and brittleness
Hardness and Brittleness
  • Figure 6.4 The repulsion between like charges causes this sodium chloride crystal to shatter when it is hit sharply.
electrical conductivity
Electrical Conductivity
  • In the solid form, ions in sodium chloride are held in the crystal lattice and are not free to move so cannot conduct electricity.
  • When the solid melts the ions are free to move.
  • In a similar way, when sodium chloride dissolves in water, the ions separate and are free to move towards the opposite charge.
properties of ionic compounds
Properties of Ionic Compounds
  • Forms crystal composed of 3d array of ions (ionic network lattice)
  • Have high melting and boiling temperatures.
  • Are hard but brittle
  • Do NOT conduct electricity in the solid state
  • They will only conduct electricity if they are melted or dissolved in water.
structure
Structure
  • From the properties we can conclude:
    • The forces between the particles are strong.
    • There are no free-moving electrons present, unlike in metals.
    • There are charged particles present, but in solid state they are not free to move.
    • When an ionic compound melts, however, the particles are free to move and the compound will conduct electricity.
naming binary ionic compounds contain 2 different elements
Naming Binary Ionic CompoundsContain 2 different elements
  • Name the metal first, then the nonmetal as -ide.

Examples:

NaCl sodium chloride

ZnI2 zinc iodide

Al2O3 aluminum oxide

practise
Practise

Complete the names of the following binary compounds:

Na3N ________________

KBr ________________

Al2O3 ________________

MgS _________________________

solution
Solution

Complete the names of the following binary compounds:

Na3N sodium nitride

KBr potassium bromide

Al2O3 aluminum oxide

MgS magnesium sulfide

transition metals
Transition Metals

Many form 2 or more positive 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

write symbols for these
Write symbols for these:
  • Potassium ion
  • Magnesium ion
  • Copper (II) ion
  • Chromium (VI) ion
  • Barium ion
  • Mercury (II) ion
criss cross method
Criss-Cross Method
  • Write the symbols for the ions side by side. Write the cation first.
    • Al3+ O2-
  • Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion.
    • Al2 O3
  • 3. Check the subscripts and divide them by their largest common factor to give the smallest possible whole-number ratio of ions. Then write the formula.
    • Al2O3
      • For Al: 2 x 3+ = 6+ For O: 3 x 2- = 6-
criss cross method1
Criss-Cross Method

Example 1: Calcium and Oxygen

O2-

Ca2+

Ca2+

Calcium

Ca2O2

O2-

Oxide

CaO

criss cross method2
Criss-Cross Method

Example 2: Magnesium and Phosphorus

P3-

Mg2+

Mg2+

Magnesium

P3-

Phosphorus

Mg3P2

  • The sum of the cation charge and the sum of the anion charge must cancel each other so that the compound formed is neutral.
practise1
Practise

1. The formula for the ionic compound of

Na+ and O2- is

1) NaO 2) Na2O 3) NaO2

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

1) Al3Cl 2) AlCl2 3) AlCl3

3. The formula of Fe3+ and O2- is

1) Fe3O2 2) FeO3 3) Fe2O3

solution1
Solution

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

sample problem 7 1
Sample Problem 7-1
  • Write the formulas for the binary ionic compounds formed between the following elements:

A. lithium and fluorine

B. lithium and oxygen

names of variable ions
Names of Variable Ions

Use a roman number after the name of a metal that forms two or more ions

Transition metals and

the metals in groups 4A and 5A

FeCl3(Fe3+) iron (III) chloride

CuCl (Cu+ ) copper (I) chloride

SnF4 (Sn4+) tin (IV) fluoride

PbCl2 (Pb2+) lead (II) chloride

Fe2S3 (Fe3+) iron (III) sulfide

ii stock system roman numerals
II. Stock system (roman numerals)
  • Example:

Fe2+

Fe3+

  • Iron(II)
  • Iron(III)

CuCl2

CuCl

  • copper(I) chloride
  • copper(II) chloride
sample problem 7 2
Sample Problem 7-2

a. Write the formula and give the name for the compound formed from the ions Cr3+ and F-.

b. Write the name for Cu3N2.

learning check
Learning Check

Complete the names of the following binary compounds with variable metal ions:

FeBr2 iron (_____) bromide

Cu2O copper (_____) oxide

SnCl4 ___(_____ ) ______________

Fe2O3 ________________________

CuS ________________________

solution2
Solution

Complete the names of the following binary compounds with variable metal ions:

FeBr2 iron ( II ) bromide

Cu2O copper ( I ) oxide

SnCl4tin (IV) chloride

Fe2O3iron (III) oxide

CuS copper (II) sulfide

learning check1
Learning Check

Name the following compounds:

A. CaO

1) calcium oxide 2) calcium(I) oxide

3) calcium (II) oxide

B. SnCl4

1) tin tetrachloride 2) tin(II) chloride

3) tin(IV) chloride

C. Co2O3

1) cobalt oxide 2) cobalt (III) oxide

3) cobalt trioxide

solution3
Solution

Name the following compounds:

A. CaO 1) calcium oxide

B. SnCl43) tin(IV) chloride

C. Co2O32) cobalt (III) oxide

learning check2
Learning Check

Write the correct formula for the compounds containing the following ions:

A. Na+, S2-

1) NaS 2) Na2S 3) NaS2

B. Al3+, Cl-

1) AlCl3 2) AlCl 3) Al3Cl

C. Mg2+, N3-

1) MgN 2) Mg2N3 3) Mg3N2

solution4
Solution

A. Na+, S2-

2) Na2S

B. Al3+, Cl-

1) AlCl3

C. Mg2+, N3-

3) Mg3N2

slide39

Practise

Name the following ionic compounds:

Na2O K2S MgBr2 AlN Ba3As2

CaCl2 AgCl AlH3 ZnI2 Li3P

slide40

Nomenclature of binary ionic compounds

Answers:

Na2O = sodium oxide K2S = potassium sulfide

MgBr2 = magnesium bromide AlN = aluminum nitride

Ba3As2 = barium arsenide CaCl2 = calcium chloride

AgCl = silver chloride AlH3 = aluminum hydride

ZnI2 = zinc iodide Li3P = lithium phosphide

iii polyatomic ions
III. Polyatomic Ions
  • A charged group of covalently bonded atoms
    • Combine with ions of opposite charge to form ionic compounds
  • Ex: NH4+, NO3-, SO42-
slide42

Nomenclature of binary ionic compounds

Some polyatomic anions that you must know:

NO3- = nitrate NO2- = nitrite

SO4 2- = sulfate SO32- = sulfite

PO43- = phosphate PO33- = phosphite

CO32- = carbonate

HCO31- = hydrogen carbonate or bicarbonate

OH- = hydroxide CN- = cyanide

C2H3O2- = acetate C2O42- = oxalate

iii polyatomic ions1
III. Polyatomic Ions
  • Most common ion is given the ending –ate.
  • One less oxygen than –ateends in–ite.
  • One less oxygen than –iteis given the prefixhypo.
  • One more oxygen than -ateis given the prefixper.

ClO3-

ClO4-

ClO2-

ClO-

  • perchlorate
  • chlorate
  • chlorite
  • hypochlorite

NO3-

NO2-

  • nitrate
  • nitrite
sample problem 7 3
Sample Problem 7-3

a. Write the formula for potassium sulfate.

b. Write the formula for calcium carbonate.

c. Write the formula for tin(IV) sulfate.

ionic nomenclature practice
Ionic Nomenclature Practice
  • potassium chloride
  • magnesium nitrate
  • copper(II) chloride

 KCl

  • K+ Cl-
  • Mg2+ NO3-

 Mg(NO3)2

 CuCl2

  • Cu2+ Cl-
slide46

Nomenclature of binary ionic compounds

Naming salts composed of the polyatomic ions is the same as with the monatomic anions. Metal name then polyatomic name.

NaOH sodium hydroxide Ba(NO3)2 barium nitrate

H2SO4 hydrogen sulfate CsNO2 cesium nitrite

Sometimes there is a common name:

KHCO3potassium hydrogen carbonate or potassium bicarbonate

  • Note: the polyatomic anions must be memorized.

Name the following ionic compounds:

NaHCO3 K2SO3 MgSO4 KCN H2PO4

Ca(OH)2 NH4NO3 Zn(NO3)2 Li3PO4 HNO3

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