Lecture 7.3- Metallic Bonds

Bellwork- Determine Formula

What is the formula of the compound formed between the following ions.

1. Calcium ion and bromide ion

2. Potassium ion and sulfide ion

3. Aluminum ion and selenide ion

Lecture 7.3 – Metallic Bonds

Ionic bonds are formed between a metal cation and a non-metal anion.

Metallic bonds are formed between two or more metal cations.

•The attraction of these free electrons to the metal cations is called a metallic bond.

Sea of Valence Electrons Model• Metal atoms release their valence

electrons into a sea of valence electrons shared by all of the metal atoms.

Atomic View of Metallic Bonding

A Group 2 metal

Each atom releases its two valence electrons into a pool of electrons to be shared by all of the metal atoms. 

Metals are ductile—they can be drawn into wires.

A force can change the shape of a metal. A force can shatter an ionic crystal.

See how metallic bonding explains some physical properties of metals.

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Metals are good electrical conductors because the valence electrons are free to travel.

Atomic View of Metallic Bonding

• Bonding in metals is not rigid.

• The same ability to reorganize explains why metals can be pulled into long, thin wires.

• As a metal is struck by a hammer, the atoms slide through the electron sea tonew positions while continuing to maintain their connections to each other.

Metal atoms are arranged in very compact and orderly patterns.

These tomatoes have a closed-packed arrangement. Similar arrangements can be found in the crystalline structure of metals.

Alloys are mixtures composed of two or more elements, at least one of which is a metal.

Alloys are important because their properties are often superior to those of their component elements.

Bicycle frames are often made of titanium alloys that contain aluminum and vanadium.

The most important alloys today are steels.

Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness.

1. The valence electrons of metals can be modeled as

a. a body-centered cube.

b. octets of electrons.

c. a rigid array of electrons.

d. a sea of electrons.

7.3 Section Quiz.

2. In most metals, the atoms are

a. free to move from one part of the metal to another.

b. arranged in a compact and orderly pattern.

c. placed at irregular locations.

d. randomly distributed.

7.3 Section Quiz.

3. Alloys are important because they

a. are pure substances.

b. are the ores from which metals can be refined.

c. can have properties superior to those of their components.

d. are produced by the combustion of metals.

7.3 Section Quiz.