Covalent and Metallic Bonds

Covalent and Metallic Bonds

How are these two items different?

Covalent bonds Metallic bonds

Covalent Bonds

Most things are held together with covalent bonds.

Characteristics• Usually low melting points• Brittle in solid state

Ex: Oxygen• low boiling point

• Gas at room temperature.

Ex: Wood: Brittle

Covalent BondAtoms share one or more electronsNonmetals need energy to transfer electrons, so 2 nonmetals

will not transfer electrons but share them to fill the valence shells.

Covalent Bonds and Molecules Substances made form covalent bonds consist of individual particles

called molecules. A molecule consists of two or more atoms joined in a definite ratio. Most molecules are composed two or more elements- like water.

Electron Dot One way to represent atom and molecule bonding is with an

electron-dot diagram The diagram only shows the valence electrons of an atom.

• Can help you predict how an atom may bond

Covalent Compounds and Molecules An atom is to an element

AsA molecule is to a compound

Simplest Molecules

The simplest molecules contain 2 bonded atoms Diatomic

The elements Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, and Bromine are always found as diatomic molecules:

More complex Molecules

Soap, plastic,& proteins are all complex molecules. Carbon is the base for a lot of these because it has a valence shell

of 4.

Metallic Bonds Metals can be shaped because of metallic bonds.

A metallic bond is formed by the attraction between positive charged metal ions and the electrons in the metal.

The positive ions form as the metals lose electrons.

Movement of Electrons throughout a Metal

Bonding in metals happens because the atoms are so close the outer energy shells overlap. This allows the valence electrons to “travel”

throughout the metal

Properties of metals

Explain what each of the following are: Conductivity

Ductility Malleability

Why can metals be bent without breaking?