Bonding Types and Properties 1. Identify compounds as ionic or molecular (covalent) based on ionic compounds being the combination of metals with nonmetals or polyatomic ions and molecules being the combination of two or more nonmetals. 2. Review how electrons interact in covalent bonds, polar covalent bonds, ionic bonds, and metallic bonds. 3. Predict physical properties of a chemical such as solubility in polar and nonpolar solvents, crystallinity, melting point and boiling point and based on understanding the general properties of ionic, polar and molecular compounds.

Chemical Bonding Elements combine chemically to increase the stability of their electrons Electrons are most stable in groups of 8 (noble gas configuration) Valence electrons can be transferred to another element or shared between elements

Bonding Within a group or column of the periodic table, the number of valence electrons is the same Similar valence electrons cause the elements in a group to react in similar ways

Ionic Bonding Transferring of electrons occurs in ionic bonding Ions are formed when electrons are gained or lost by an element Metals lose electrons to form cations (+ charge) Non-metals gain electrons to form anions (- charge) Opposite charges attract to form the final compound

Ionic Bonding How many electrons are gained or lost? It depends on how many electrons are in the valence shell If fewer than 4, electrons are lost to get to 8 If more than 4, electrons are gained to get to 8

Valence electrons and Lewis Dots Review Activity nit3ValenceElectrons.htmhttp:// nit3ValenceElectrons.htm

Ionic Bonding Ionic Compounds are usually made of a metal and 1 or more nonmetals Formula Unit is smallest ratio of ions No single particle of an ionic compound exists

Ionic Bonding Properties of ionic compounds High melting points > 300 C High boiling points Crystalline solids at room temperature May dissolve in water but not in non-polar solvents such as oil Conduct electricity when dissolved in water or when melted

Covalent Bonding Sharing valence electrons between atoms Valence electrons are shared to allow each atom to have a share of 8 electrons (2 for H) Occurs between non-metals and hydrogen Single particle called a molecule

Covalent Bonding Properties of covalent (molecular) compounds Low melting points < 300C Low boiling points May be solid, liquid or gas at room temperature Poor electrical conductors May dissolve in non-polar solvents, but not in water

Identifying Compounds as Ionic or Covalent Ionic Compounds Metal with 1 or more non-metals Covalent (Molecular) Compounds Two or more non-metals (including H as a non-metal) Review activity docker.demon.co.uk/as_a2/topics/ionic_and_covalent_b onding/quiz_1.htmlhttp:// docker.demon.co.uk/as_a2/topics/ionic_and_covalent_b onding/quiz_1.html

Polar Covalent Bonds Sometimes electrons are not shared equally between the atoms in a covalent bond Leads to partial charges on the atoms The atom which attracts the electrons the most is slightly negative The atom which attracts the electrons the least is slightly positive Water is an example of a polar covalent bond

Polar Covalent Bonds Partial charges allow greater attraction between molecules of compound Higher than expected boiling and melting points Able to dissolve some ionic compounds and other polar compounds

Network Covalent Solids Network solids are giant arrangements of matter in which atoms are covalently bonded together in a continuous two or three dimensional array. You can think of network solids as giant molecules. Common examples of network solids include diamond and quartz. A network solid has exceptional hardness and a high melting and boiling point.

Covalent Network Solids

Bonding in Metals Metals have high boiling points and melting points-Why? Must be something holding the atoms together Weakly held valence electrons move freely between atoms of metals, holding atoms together

Bonding in Metals Sea of electrons theory

Review of Bonding y/gilbert/tutorials/interface.asp?chapter=cha pter_06&folder=bondinghttp:// y/gilbert/tutorials/interface.asp?chapter=cha pter_06&folder=bonding imations/chang_7e_esp/bom1s2_11.swfhttp:// imations/chang_7e_esp/bom1s2_11.swf