Chapter 4 Part 1 - Ionic Compounds

Electron Review l Valence electrons - electrons in the outer energy level. l Core electrons -those in the energy levels below.

Electron Review Which type of electron is responsible for bonding? Why?

Electron/Periodic Table Review l Atoms in the same column: –Have the same outer electron configuration. –Have the same valence electrons. –Easily found by looking up the group number on the periodic table.

Electron/Periodic Table Review Group 2A How many Valence Electrons? Group 8A How many Valence Electrons?

Noble Gas Configuration Q: What’s so special about 8 electrons? A: STABILITY!

Noble Gas Configuration All atoms seek to achieve the same stability of a noble gas by gaining, losing, or sharing electrons with another atom. HOW?

Noble Gas Configuration THROUGH BONDING! Ionic bonding Covalent bonding

Review Question Group 1A and 2A are what type of element? (metal, nonmetal, metalloid)

Metals l Metals lose electrons to attain noble gas configuration. l They make positive ions called cations.

Electron Dots For Cations Metals will have few valence electrons Ca

Electron Dots For Cations l Metals will have few valence electrons l These will come off Ca

Electron Dots For Cations l Metals will have few valence electrons l These will lose electrons l Form positive ions Ca 2+

Review Question Group 5A elements are mostly what type of element? (metal, nonmetal, metalloid)

Nonmetals l Nonmetals gain electrons to attain noble gas configuration. l They make negative ions called anions

Electron Dots For Anions l Nonmetals will have many valence electrons. l They will gain electrons to fill outer shell. P P 3-

Noble Gas Configurations l All atoms react to achieve noble gas configuration. l Noble gases have 8 valence electrons l Also called the octet rule. Ar

Ionic Bonding l Anions and cations are held together by opposite charges. l These are called ionic compounds l Ionic compounds are also called salts.

Ionic Bonding l The bond is formed through the transfer of electrons. l Electrons are transferred to achieve noble gas configuration by both metal and nonmetal.

Ionic Bonding NaCl

Ionic Bonding Na + Cl -

Ionic Bonding l All the electrons must be accounted for! CaP

Ionic Bonding CaP

Ionic Bonding Ca +2 P

Ionic Bonding Ca +2 P Ca

Ionic Bonding Ca +2 P -3 Ca

Ionic Bonding Ca +2 P -3 Ca P

Ionic Bonding Ca +2 P -3 Ca +2 P

Ionic Bonding Ca +2 P -3 Ca +2 P Ca

Ionic Bonding Ca +2 P -3 Ca +2 P Ca

Ionic Bonding Ca +2 P -3 Ca +2 P -3 Ca +2

Ionic Bonding Ca 3 P 2 Ionic Compound

Properties of Ionic Compounds l Crystalline structure. l A regular repeating arrangement of ions in the solid. l Ions are strongly bonded. l Structure is rigid. l High melting points- because of strong forces between ions.

Crystalline structure

Do they Conduct? l Conducting electricity is allowing charges to move. l In a solid, the ions are locked in place. l Ionic solids are insulators. l When melted, the ions can move around. l Melted ionic compounds conduct. l Have to get them to 800ºC. l Dissolved in water they conduct – electrons are free to move.

Ionic solids are brittle

l Strong Repulsion breaks crystal apart.

Metallic Bonds l How atoms are held together in a metal solid. l Metals hold onto there valence electrons very weakly. l Think of them as positive ions floating in a sea of electrons. l Electrons are free to move from atom to atom. l Electrons moving = electricity!!!

Sea of Electrons l Electrons are free to move through the solid. l Metals conduct electricity.

Metals are: l Malleable - Hammered into shape (bend). l Ductile - drawn into wires.

Malleable

l Electrons allow atoms to slide by.