CHEMICAL BONDING Cocaine To play the movies and simulations included, view the presentation in Slide Show Mode.

Types of Chemical Bonds Ionic Bond: Chemical bonding that results from the bonding between metals and nonmetals. Electrons are transferred from one atom to another, from the metal to the nonmetal.

Atoms that lose valence electrons (METALS) become positively charged and are known as CATIONS. Atoms that gain valence electrons (NONMETALS) become negatively charged and are known as ANIONS.

Properties of Ionic Compounds Are hard, rigid, brittle crystalline solids which may or may not dissolve in water. Have high melting and boiling points. Can be good conductors, it depends.

Do They Conduct Electricity? Conducting electricity is allowing charges to move. In a solid, the ions are locked in place. Ionic solids do not conduct When melted, the ions can move around. Melted ionic compounds do conduct. When dissolved in water, the ions can move around. Solutions in water do conduct.

Metallic Bonds Two metals do not transfer electrons to other metals nor do they share electrons. Their valence electrons are not held to any specific atom in the solid metal and can move freely from one metal atom. Think Hot Potato! (Electron Sea Model).

Properties of Metals Because these delocalized electrons are free to move, metals are excellent conductors of electricity and heat. They have a luster and are malleable, ductile, and usually durable. Melting points are variable but boiling points are all high. +

Metal Alloys Metals do not combine with metals. They form alloys which is a solution of a metal dissolved in another metal. Examples are steel, brass, bronze and pewter.

Covalent bond: Chemical bonding that results from the sharing of electrons between two atoms Covalent bonds equally share (NONPOLAR) or unequally share (POLAR) electrons between the atoms.

Properties of Covalent Compounds Because covalent bonds are generally weaker than ionic bonds, the melting points and boiling points of covalent compounds are generally lower than those of ionic compounds. Many covalent compounds exist as gases at room temperature.

Review of Chemical Bonds There are 3 forms of bonding: _________—complete transfer of 1 or more electrons from one atom to another forming oppositely charged ions that attract one another _________—some valence electrons shared between atoms _________ – holds atoms of a metal together Most bonds are somewhere in between ionic and covalent.