Chapter 7 - Ionic and Metallic...
Transcript of Chapter 7 - Ionic and Metallic...
Chemistry Regents Page 1 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 Page 2 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
Chemistry Regents Page 3 of 6Mr. Markic
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
Chemistry Regents Page 4 of 6Mr. Markic
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 Page 5 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
Chemistry Regents Page 6 of 6Mr. Markic
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