Bonding

Three Types We will study... Ionic Bonding Covalent Bonding Metallic Bonding occurs between a metal and a nonmetal occurs between two nonmetals occurs WITHIN a metal sample

Electron Configuration Remember that electron configuration refers to the arrangement of electrons in the orbital of an atom!

Ionic and Covalent Bonding Video clip zWwwwhttp:// zWwww

Chemical Bonding Compounds are formed from chemically bound atoms or ions. Bonding involves only the valence electrons.

Valence Electrons Electrons are found in specific orbits/clouds spinning around the nucleus Valence electrons are the electrons located in the outermost orbit Elements become stable when: their outer orbit contains 8 electrons or their outer orbit becomes empty Lewis Dot Diagrams show the # of Valence Electrons

Why are the noble gases unreactive? The Octet Rule When the highest energy level of an atom is filled, the atom is stable. Atoms tend to gain, lose, or share electrons until they have eight valence electrons. **Hydrogen and Helium are the only exceptions. Because they are so small, they are satisfied with two valence electrons.

Lewis Symbols / Electron Dot Diagram Lewis symbols show the valence electrons as dots arranged around the atomic symbol. hydrogen: sodium: chlorine: Na  H  Cl  

Dot Diagrams Show the number of valence electron

Ionic Bonds form between a metal and a nonmetal form as a result of a transfer of electrons Na becomes a positive ion Cl becomes a negative ion Cation means “to go down” – also think cast off Anion means “to go up” –Also think accept Na  Cl   cation Anion So, an Ion is a Charged Particle!!!

Ionic Bonds (Metal and Nonmetal) Loss of Electrons is Oxidation Gain of Electrons is Reduction LEO the Lion says GER So, the OXIDATION NUMBER is the charge of the ion.

What is the oxidation number of Na when it combines with Cl? What is the oxidation number of Cl when it combines with Na? What is the oxidation number of O? What is the oxidation number of Mg?

Ionic Bonds What is the formula for the compound that forms between magnesium and chlorine? Cl   Mg  Cl  

Ionic Compounds Ionic compounds consist of a lattice of positive and negative ions.

Ionic Compounds, Characteristic Properties High melting points High boiling points Conduct electric current when melted and when dissolved in solution All of these properties are a result of the strong attraction among ions within the crystal lattice

What are some of the characteristics of Ionic Bonds?

Covalent Bonds (Molecular Bonds) form between two nonmetal atoms form as a result of a sharing of electrons

Polar Molecules There is an uneven distribution of charge…one atom has a stronger attraction for the electrons than the other Polar molecules attractions are stronger than nonpolar molecules

Molecular Compounds, Characteristic Properties Low melting points Low boiling points Usually gases or liquids at room temp. Does not conduct electricity well May or may not dissolve in water (there are several types of molecular compounds) Note the correct name for a compound that contains covalent bonds

Double Bubble – Compare/Contrast Ionic and Covalent Bonding

Molecular Compounds, Lewis Structures Covalent bonding in a molecule can be represented by a Lewis structure containing bars that represent shared pairs of electrons.  Cl  Cl  Cl 2 Cl   Cl   + Cl Cl  Bonding electrons Nonbonding electrons

Double and Triple Bonds Atoms can share four electrons to form a double bond or six electrons to form a triple bond. O2O2 N2N2 = O  N 

Complete Bonding Basics Worksheet

Metallic Bonding Holds atoms of metals together A metallic bond is the attraction between a metal cation and the shared electrons that surround it. Found in pure metals (copper, iron) and alloys (steel, brass, bronze, etc)

Metallic Bonding Metal atoms release their valence electrons to be shared by all metal cations Metal cations in a “sea” of mobile valence electrons

The metallic bonds in some metals are stronger than in other metals. The more valence electrons, the stronger the metallic bonds will be. Do alkali metals have strong bonds? NO!! Only 1 valence electron!! What about Tungsten? YES!!

Metallic Bonding, Characteristic Properties Good conductors of heat and electricity because of mobile electrons High melting points because of strong attraction of positive metal ions and negative electrons –(sodium has a low melting point, Tungsten has a very high melting point…WHY?)

Metallic Bonding, Characteristic Properties Lustrous Malleable and Ductile because metal ions can slide past each other

Structure of Metals Metallic bond- metal cation and shared electrons, very strong, malleable –Free moving electrons Alloy- mixture of 2 or more elements, one of which is a metal Gold (24-karat vs. 12-karat) (100% vs. 50% pure)

Metal Structure, continued Can design alloys with specific properties Copper alloys –Bronze copper and tin –Clear, loud tone –Brass Copper and zinc –Duller tone that dies quickly Steel Alloys- adding carbon to steel to strengthen it, along with other metals Aluminum alloys are light and sturdy

Wanna hear a nitrogen monoxide joke? NO! Wanna hear me tell a Potassium Joke? K!