Chemical Bonding

Bellringer What types of elements form an ionic bond? What types of elements form a covalent bond? What are some characteristics of ionic compounds? What are some characteristics of covalent compounds?

Three Types of Bonds 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! 2 8 18 32

Ionic and Covalent Bonding Video clip http://www.youtube.com/watch?v=QqjcCvzWwww

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

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. Why are the noble gases unreactive?

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

Dot Diagrams Show the number of valence electrons http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/perlewis.html

Ionic Bonds form between a metal and a nonmetal form as a result of a transfer of electrons Na becomes a positive ion called = Cl becomes a negative ion called = 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 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

Animated Reaction with sodium and chlorine http://www.visionlearning.com/library/module_viewer.php?mid=55 https://www.youtube.com/watch?v=oZdQJi-UwYs

Naming Ionic Compounds 1) Write the name of the metal 2) Shorten the name of the non-metal and add the suffix -ide KCl = potassium chloride 3) **If the Metal is a Transition Metal, after the metal name, give its charge in Roman Numerals CuSO4 = Copper (II) Sulfate

Polyatomic Ions If the compound contains a polyatomic ion, just name the ion as it appears on the list.

Practice Naming Ionics MgBr2 PbO Na3PO4 Na2O CdO KOH Al2O3 NH4NO3 CsC2H3O2 KMNO4

Writing Ionic Formulas You must balance the ions Same amount of (+) as (-) Sodium Sulfide Na (1+) & S (2-) So Na2S See p.173-174 in text Steps: write symbols write charges cross-over charges from top to bottom remove the charge simplify numbers and remove the 1s

Practice Aluminum Oxide Aluminum Bromide Potassium Oxide Sodium Chloride Cesium Sulfide Rubidium Fluoride Magnesium Nitride

What are some of the characteristics of Ionic Bonds? Need at least 7 facts/characteristics 3 Examples of Ionic Bonds

Bell ringer What is a positive ion called? How are positive ions formed? What are some of the characteristics of ionic compounds?

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

Covalent Bonding animation

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

Polar covalent bonding in a water molecule animation

Molecular Compounds, Characteristic & Properties Note the correct name for a compound that contains covalent bonds 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)

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 · · Bonding electrons Cl2 Cl Cl · · Nonbonding electrons

Double and Triple Bonds Atoms can share four electrons to form a double bond or six electrons to form a triple bond. = O O · · O2 · · N N  N2

Naming Molecular Compounds To name molecular compounds you need to use prefixes to indicate the number of atoms of each element present. You CANNOT use prefixes to name ionic compounds only molecular

Naming Molecular Compounds Prefix to indicate the number of atoms of each element in a compound's formula Exception: "mono" is not used in front of first element's name. Change ending of last element to "ide". Mono- Hexa- Di- Hepta- Tri- Octa- Tetra- Nona- Penta- Deca-

Practice N2O5 SO3 CO P4O10 As2O

Practice Writing Molecular Formulas Silicon Dioxide Carbon Monoxide Trioxide Pentachloride Diarsenic Hexanitride Boron Trifloride

Double Bubble – Compare/Contrast Ionic and Covalent Bonding Need at least 15 fact/characteristics Need at least 3 examples of each

Bell Ringer Use the criss cross method to find the formula for Magnesium Chloride. What is the name for SiO2

Work in Textbook!! P. 174 – Math practice #1-4

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 Ex. Gold (24-karat vs. 12-karat) (100% vs. 50% pure)

Sasinschools quick launch 46 What are the rules for deciphering "code names" such as NaCl, CO, and Cu(OH)2?

Bell Ringer What is an ion? What is the electron configuration of a sulfur atom? If an atom gains 2 electrons in a chemical compound, what is its charge? Which element is most likely to gain electrons in a chemical reaction? a) Ca b) Ba c) Kr d) Br