chapter 7 - ionic and metallic...

Chemistry Regents of 6Mr. Markic

Chapter 7 - Ionic and Metallic Bonding

IonsHow does an atom become an ion and what charge does it become?

What elements lose an electron and what are they called?

What elements gain electrons and what are they called?

Why do the elements lose electrons?

Why do the elements gain electrons?

What are valence electrons?

Practice ProblemsHow many valence electrons are in each atom?

a) Potassium

b) Carbon

c) Magnesium

d) Oxygen

Electron dot structure of some representative elements

H He

Li Be O F Ne

Na Mg S Cl Ar

The Octet Rule

Chemistry Regents of 6Mr. MarkicIn forming compounds atoms try to achieve the electron configuration of a noble gas

Why?

Metals want to Nonmetals want to

Practice ProblemsHow many electrons will each element gain or lose in forming an ion?a) Calcium

b) Fluorine

c) Aluminum

d) Oxygen

Write the name and symbol of the ion formed whena) A potassium atom loses one electron

b) A zinc atom loses two electrons

c) A fluorine atom gains one electron

Ionic bonds composed of cations and anions called compounds

Cations - Anions –

Have opposite charges (+) and (-)and attract each other – electrostatic force Transfer of electrons Electrically neutral

CationsMetals tend to lose electrons

Na → Mg →

AnionsNonmetals tend to gain electrons

Cl + e- → O + 2e- →

Sample Problems

Na + Cl → Mg + Cl →

Use electron dot structures to predict the formulas of potassium and oxygen


K O

Properties of Ionic Compounds Crystalline _____________ at room temperature Do __________ conduct electricity (__________) ____________ melting points Conduct _________________ (when dissolved in ___________)

Bonding in Metals (Metallic Bonding) A metal structure is of closely packed cations Metals bound to metals Are ductile, malleable, and good conductors of heat and

electricity The cation is surrounded by _____________________________ free floating valence electrons

Alloys Mixtures that contain a metal & one or more ‘other’ elements Superior propertiesExamples:

Brass–

Bronze –

White gold–

Solder-

Ionic FormulasUse the element’s oxidation number


Binary Ionic FormulasCation is first then anion

ExamplesNa+ + Cl- →

Ca2+ + Cl- →

Al3+ + O2- →

Crisscross Method1. Crisscross the charges in the monatomic ions

2. Drop the signs

3. Reduce to the simplest ratio (empirical)

Al 3+ + O2- →

Mg2+ + O2- →

K+ + O2- →

Pb4+ + O2- →

Ca2+ + P3- →

Polyatomic Ions Table E Composed of more than one atom Group of atoms that comprise a charge (ion) Compounds with polyatomic ions Must be neutral Contains at least three elements

Al3+ + PO43- →

Na+ + SO42- →

Ca2+ + OH- →

NH4+ + SO4

2- →

K+ + CrO42- →

Naming IonsCations

Chemistry Regents of 6Mr. Markic Write the name of the element followed by the word ion

Anions Write the root name of the element with an –ide ending followed by the word ion

Practice ProblemsWrite the name of the ion

K+ I-

S2- O2-

Al3+ N3-

Mg2+

Multiple Oxidation States Naming is based on its oxidation number Roman numeral is assigned No roman numeral needed for only one oxidation number

ExampleMn2+

Mn4+

Mn7+

Naming Binary Compounds Name the cation first, followed by the anion name (ends in )

Practice ProblemsName the following ions

CaCl2

Li2S

NaF

KI

Naming cations with multiple oxidation numbers Cation is named first The oxidation number is written in roman numeral after the cation The anion name is writtenPractice exerciseName the following ions


CuCl2

Fe2O3

Au2O

TiCl4

Naming Compounds with Polyatomic Ions 1st write the symbol for the cation 2nd write the formula for the polyatomic ion (found on table E)

Practice ExerciseName the following compounds

NaOH

CuSO4

CaCO3

Fe(NO3)3

Writing formulas from names• Determine the cation element symbol and oxidation state

• If a roman numeral is given-it refers to the cations oxidation number

• If a polyatomic ion is given, use table E to determine its symbol and charge

• Cation is written first, then the anion

• Use the criss-cross method to achieve a neutral compound

• Always reduce subscripts (empirical)

Practice ProblemsWrite formulas for compounds formed from these pairs of ions.

a) Calcium acetate

b) Sodium perchlorate

c) Magnesium hydrogen carbonate

d) Chromium (III) nitrite

chapter 7 - ionic and metallic...

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