Ch. 12 Chemical Bonding pp. 309-323

Structure of Atom Nucleus  Proton –Positive Charge Neutron-No Charge Electron Cloud  Electron (Negative Charge)

Each Element has a different Atomic Structure consisting of a specific number of Protons, Neutrons, and Electrons The number and arrangement of Electrons in the Electron Cloud determines the Physical and Chemical Properties of the Element

A Chemical Change is the result of a Chemical Bond Chemical Bond – joining of Atoms to form new substances H + H + O = Water H20

By Losing Electrons By Gaining Electrons By Sharing Electrons 4 Ways To Form Bonds By Losing Electrons By Gaining Electrons By Sharing Electrons By Pooling Electrons

How Do You Find Number Electrons Number of Electrons in an Atom can be determined from the Atomic Number If Atom has No Charge, then the Atomic Number will be equal to number of Electrons

Electron Organization Electrons in an Atom are organized in Energy Levels within Electron Cloud Each Energy Level represents a different amount of energy Each Energy Level can hold a specific number of Electrons

The farther an Energy Level is from the Nucleus, the more electrons it can hold Electrons in the First Energy Level have the lowest amount of Energy Electrons in the Fourth Energy Level have the highest amount of Energy

Energy Level 1 = 2 Electrons

Valence Electrons Used to form Chemical Bonds Electrons in the outermost Energy Level Used to form Chemical Bonds Within a Group, the Atoms have the same number of Valence Electrons

To Bond or Not To Bond Not all Atoms bond the same way Group 18 (Noble Gases) will not form bonds

-- Exceptions are Hydrogen and Helium (only need 2 Valence Electrons) Goal  Have a full outermost energy level (valence) -- 8 Valence Electrons -- Exceptions are Hydrogen and Helium (only need 2 Valence Electrons)

Noble Gases (Group 18) -- already have 8 Valence Electrons Halogens (Group 17) -- have 7 Valence Electrons and needs 1 more to stable Alkali Metals (Group 1) -- have 1 Valence Electron but needs 7 more to be stable -- it is easier to lose 1 than gain 7

Ionic Bonds Bond that forms when Electrons are transferred from one Atom to another, which results in a positive ion and a negative ion (opposite charged ions that attract each other)

Ion Formed by Losing, Gaining, Sharing, or Pooling Electrons Atom that is no longer neutral because it has gained or lost an Electron Formed by Losing, Gaining, Sharing, or Pooling Electrons

Forming Positive Ions More Protons than Electrons Metal Atoms tend loss Electrons Takes small amount of energy to remove Electrons from atoms in elements from the Alkali Metals (Groups 1) and Alkaline Earth Metals (Groups 2)

Forming Negative Ions More Electrons than Protons Nonmetal Atoms tend gain Electrons The more easily an Atom gains Electrons, the more energy the Atom releases

*CATION-when an atom gives up an electron to another atom and has a positive charge. *ANION-when an atom gains an electron and has a negative charge.

Ionic Compound Ionic Bonds form when the number of electrons lost by the Metal Atoms equals the number gained by the non-metal atoms The Ions that Bond are charged, but the compound is Neutral (They Cancel Each Other Out)

Ionic Compound When Ions Bond, they form repeating 3-D patterns called a Crystal Lattice Strong attraction between Ions gives the following properties: brittleness, high melting points, & high boiling points

Electron Dot Diagram Chemical symbol for an Element, surrounded by as many dots as there are Electrons in its outer energy level Dots are written on the four sides of the symbol and each dot represents a single Electron

Electron Dot Diagram Start by writing one dot on the right of the Element symbol, then add dots to the left, top, and bottom

Covalent Bond Forms when Atoms share one or more pairs of Electrons Low Melting Points, Low Solubility, low boiling points, brittle in solid state Most of the things you see everyday (Water, Sugar, Oxygen, Wood)

* Single Covalent Bond- when two valence electrons are shared by two atoms. * Double Covalent Bond- when four valence electrons are shared by two atoms.

When 2 Atoms of Non-Metals Bond, a large amount of Energy is needed to either Atom to lose an Electron (so they will share Electrons) Substances containing Covalent Bonds consist of individual particles called Molecules

Simplest Molecules Diatomic Molecules – Molecules made up of 2 Atoms Diatomic Elements – Elements found in Nature as Diatomic Molecules (Oxygen, Nitrogen, Fluorine, Chlorine, Bromine, Iodine)

Metallic Bonds What gives Metals their properties Bond formed by the attraction between positively charged Metal Ions and the Electrons around them What gives Metals their properties (Malleable, Ductile, Conduct Electricity) --because the outermost energy level overlaps, they can bond in different directions