Bonding Types and PropertiesBonding 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 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

BondingBonding

• 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 BondingIonic 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 BondingIonic 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

Valence electrons and Lewis Dots

• Review Activity• http://www.sciencegeek.net/Chemistry/taters/

Unit3ValenceElectrons.htm

Ionic BondingIonic 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 BondingIonic 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 BondingCovalent 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 BondingCovalent 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

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• http://www.mp-docker.demon.co.uk/as_a2/topics/

ionic_and_covalent_bonding/quiz_1.html

Polar Covalent BondsPolar 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 BondsPolar 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 SolidsNetwork 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 SolidsCovalent Network Solids

Bonding in MetalsBonding 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 MetalsBonding in Metals

• Sea of electrons theory

Review of BondingReview of Bonding

• http://www.wwnorton.com/college/chemistry/gilbert/tutorials/interface.asp?chapter=chapter_06&folder=bonding

• http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/bom1s2_11.swf