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Ch 8 Ionic Bonds
Transcript of Ch 8 Ionic Bonds
and Metals. Sec 8.1
Forming Chemical Bond Formation and
Nature of Ionic Bonds Sec 8.2 Sec 8.3
Names and Formulas
for Ionic Compounds Sec 8.4
and properties of Metals form by the attraction between the positive nucleus of one atom and the negative electrons of another atom. chemical bond -force that holds two atoms together. Valence Electrons and Chemical Bonds Atom’s try to form the octet—
the stable arrangement of eight valence electrons in the outer energy level
by gaining or losing valence electrons. Valence Electrons and Chemical Bonds (cont.) Section Check SECTION8.1 Oxygen gains two electrons to form what kind of ion?
A. 1– anion
B. 2– anion
C. 1+ cation
D. 2+ cation Metals are reactive because they lose valence electrons easily. Positive Ion Formation (cont.) Section Check SECTION8.1 Elements with a full octet have which configuration?
A. ionic configuration
B. halogen configuration
C. noble gas configuration
D. transition metal configuration Some nonmetals can gain or lose electrons to complete an octet. Nonmetal ions - gain the number of electrons required to fill an octet. Negative Ion Formation (cont.) Form by gaining electrons
EX: Cl An anion - negatively charged ion. Negative Ion Formation Ion Formation lose valence electrons to form
EX: Na A positively charged ion -cation. Positive Ion Formation Other relatively stable electron arrangements are referred to as pseudo-noble gas configurations. Transition metals - form 2+ or 3+ ions, but can form greater than 3+ ions.
Difficult to predict them Positive Ion Formation (cont.) Section Check What is the electrostatic charge holding two ions together?
A. covalent bond
B. pseudo-noble gas bond
C. crystal lattice bond
D. ionic bond During chemical reactions- energy is either absorbed or released
Reactions that absorb energy are endothermic.
Reactions that release energy are exothermic. Energy and the Ionic Bond 3-D arrangement of particles, and is responsible for the structure of many minerals. The strong attractions among the positive and negative ions result in the formation of the crystal lattice. Properties of Ionic Compounds (cont.) EX: calcium flouride
Pg 217 Practice Prob Formation of an Ionic Bond (cont.) Formation of an Ionic Bond (cont.) Ionic Bonds and Ionic Compounds SECTION8.2 Ionic Bonds and Ionic Compounds SECTION8.2 Compounds with ionic bonds -ionic compounds.
Binary ionic compounds contain only two different elements—a metallic cation and a nonmetallic anion. Compounds form when elements react
2 Types – Ionic and Covalent
ionic bond- The electrostatic force that holds oppositely charged particles together Formation of an Ionic Bond The repeating pattern of particle packing in an ionic compound - ionic crystal. Positive and negative ions exist in a ratio determined by the number of electrons transferred from the metal atom to the non-metal atom. Properties of Ionic Compounds Elements want to gain stable configuration – can gain or lose by forming ionic bonds (want octet)
Number of electrons lost must equal the number of electrons gained
become neutral compound
Draw electron dot formation
Use charges Formation of an Ionic Bond (cont.) Melting point, boiling point, and hardness depend on the strength of the attraction. Properties of Ionic Compounds (cont.) Section Check Which subscripts would you most likely use for an ionic compound containing an alkali metal and a halogen? (Remember, 1 = no written subscript)
A. 1 and 2
B. 2 and 1
C. 2 and 3
D. 1 and 1 SECTION8.2 Names for Ions and Ionic Compounds (Cont.) oxyanion - polyatomic ion composed of an element (usually a non-metal), bonded to one or more oxygen atoms. Names for Ions and Ionic Compounds Practice pg 225 Formulas for Ionic Compounds (cont.) EX: Potassium and Oxygen
Aluminum and Sulfer
Practice pg 224 Formulas for Ionic Compounds (cont.) 2) Subscripts represent the number of ions of each element in an ionic compound.
3) The total charge must equal zero in an ionic compound. – use oxidation numbers to help determine ratio Rules for writing formulas:
1) The symbol for the cation is always written 1st, followed by the symbol of the anion. Monatomic ions are one-atom ions.
Oxidation number, or oxidation state, is the charge of a monatomic ion. Formulas for Ionic Compounds (cont.) Names and Formulas for Ionic Compounds SECTION8.3 Chemical formulas and the name of the compound must be understood by all
Use a standardized system for naming Formulas for Ionic Compounds EXAMPLES:
Pg 226 Names for Ions and Ionic Compounds (Cont.) Name the cation followed by the anion.
For monatomic cations use the element name.
For monatomic anions, use the root element name and the suffix –ide.
For different oxidation states of the same element:
oxidation state is written in parentheses after the name of the cation.
When the compound contains a polyatomic ion, just name of the polyatomic ion. Chemical nomenclature rules for naming compounds. exist as a unit, never change subscripts of the atoms within the ion.
If more than one polyatomic ion is needed, use parenthesis . Polyatomic ions - ions made up of more than one atom. Formulas for Ionic Compounds (cont.) A formula unit represents the simplest ratio of the ions involved.
Remember – must form neutral compound Formulas for Ionic Compounds (cont.) Section Check What is the name of the compound Ca(OH)2?
A. calcium oxide
C. calcium hydroxide
D. calcium peroxide Section Check The attraction of a metallic nuclei and delocalized electrons forms what kind of bond?
D. metallic Metallic Bonds and the Properties of Metals (Cont.) The electron sea model proposes that all metal atoms in a metallic solid contribute their valence electrons to form a "sea" of electrons.
The electrons are free to move around and are referred to as delocalized electrons, forming a metallic cation. Within the crowded lattice, the outer energy levels of metal atoms overlap. SECTION8.4 Metals also form lattices in the solid state, where 8 to 12 other atoms closely surround each metal atom. Metals are not ionic but share several properties with ionic compounds. Metallic Bonds and the Properties of Metals Section Check Which property of metals allows them to be easily drawn into wires?
D. durability Metallic Bonds and the Properties of Metals (Cont.) A metallic bond is the attraction of an metallic cation for delocalized electrons. The properties of alloys differ from the elements they contain.
Ex. Steel is iron mixed with at least one other element. Some properties of iron are present, like magnetism, but steel is stronger than iron. An alloy is a mixture of elements that has metallic properties.
Ex. Stainless steel, brass, cast iron Metal Alloys