Chapter 7 Ionic and Metallic Bonding
7.1 Ions
7.2 Ionic Bonds and Ionic Compounds
7.3 Bonding in Metals
7.1 Ions
Key Concepts
1. How do you find the number of valence electrons in an
atom of a representative element?
2. Atoms of which elements tend to gain electrons?
3. Atoms of which elements tend to lose electrons?
4. How are cations formed?
5. How are anions formed?
1. Elements within each group of the periodic table behave
similarly because they have the same number of valence
electrons.
2. Valence Electrons – are the electrons in the highest
occupied energy level of an element’s atoms.
3. The number of the valence electrons largely determines
the chemical properties of an element.
4. The valence number of electrons in an atom of a
representative element is simply the group number for
which the element belongs.
5. Valence electrons are usually the only electrons used in
chemical reactions.
6. Electron dot structures are diagrams that show the
number of valence electrons as dots around the atom.
The Octet Rule:
1. Noble gases are unreactive
2. Noble gases are stable
3. In 1916, Gilbert Lewis used this fact to explain why atoms
form certain kinds of ions and molecules.
4. In forming compounds, atoms tend to achieve the electron
configuration of a noble gas.
5. An octet is a set of eight electrons.
6. All noble gases except Helium have an octet of valence
electrons
7. Metallic elements tend to lose their valence electrons,
leaving a complete octet in the next lowest energy level.
8. Nonmetals tend to gain or share electrons with other
nonmetals to achieve a complete octet.
Formation of Cations:
1. A neutral atom has the same number of protons and neutrons.
2. An ion forms when an atom in a group loses or gains a certain
number of electrons.
3. A cation is produced when atoms lose valence electrons.
4. Cations are positively charged atoms
5. The electron configuration of the cation resembles that of the
previous noble gas
6. For transition metals, the charges of cations can vary.
7. An atom of Fe can lose two or even three electrons Fe2+ Fe3+
8. Notice the charge is written as a superscript
9. Some ions formed by transition metals do not have noble-gas
electron configuration.
10.Transition metals tend to borrow an electron from their s orbital
so that the d orbitals are filled giving theses elements a pseudo
noble-gas configuration
11. Examples – Ag, Cu, Au, Cd, and Hg
Formation of Anions:
1. An anion is an atom from a group that has a negative charge.
2. The negative charge on the atoms occurs because the atom gains
electrons.
3. The name of an anion typically ends with an –ide
4. For example Chlorine becomes Chloride
5. By gaining electron the atoms attain noble-gas electron
configuration
6. Halogens – form halide ions and have a 1- charge
7.2 Ionic Bonds and Ionic Compounds
Key Concepts
1. What is the electrical charge of an ionic compound?
2. What are three properties of ionic compounds?
Formation of Ionic Compounds
1. Compounds composed of cations and anions are called ionic
compounds.
2. Ionic compounds usually form from metallic cations and
nonmetal anions.
3. Ionic compounds are electrically neutral.
4. The total positive charge of the actions equal the total
negative charge of the anions
5. The charge is called the atoms oxidation number
6. The oxidation number is written as a superscript
7. Na Cl is an ionic compound –what are there charges?
8. Try these Mg + F , Ca + O , K + N
9. Ionic bonds are held together by electrostatic forces
10.The bond is created when the cation loses its electron(s) to
and anion
11. Each atom in the bond becomes charged and both have stable
octets.
Formula Units
1. Chemical Formula – is a shorthand way to represent the kinds
and numbers of atoms in the compound
2. Formula unit – is the lowest whole-number ratio of ions in an
ionic compound.
3. Superscript – charge or oxidation number
4. Subscript – the amount of the atoms present in the
compound
5. So what is the ratio of a Magnesium Chloride compound?
6. Notice – the cation is first in the name and anion is second
with an –ide at the end of the name.
7. Two atom compounds are called binary compounds.
Properties of Ionic Compounds
1. Most ionic compounds are crystalline solids at room
temperature.
2. The ions in such crystals are arranged in repeating threedimensional patterns.
3. In sucha a way, ionic compounds create strong attractive forces
between the ions resulting in very stable structures.
4. Ionic compounds generally have high melting points
5. Coordination number – is the number of ions of opposite charge
that surround the ion in a crystal.
6. Ionic compounds can conduct an electrical current when melted
or dissolved in water.
7.3 Bonding in Metals
Key Concepts:
1. How can you model the valence electrons of metal atoms?
2. How are metal atoms arranged?
3. Why are alloys important?
Metallic Bonds and Metallic Properties
1. Metals are made of closely packed cations rather than
neutral atoms.
2. The valence electrons of metal atoms can be modeled as a
sea of electrons.
3. The valence electrons are mobile and can drift freely in
the metal
4. Metallic bonds – Consist of the attraction of the freefloating valence electrons for the positively charged metal
ions.
5. The sea-of-electrons explain many physical properties of
metals
a. good conductors
b. ductile
c. malleable
Crystalline Structure of Metals
1. Metal atoms are arranged in very compact and orderly patterns.
2. Metals of one atom have the simplest form of crystalline solids.
3. Arrangements of crystals include;
a. Body centered cubic – Na, K, Fe, Cr, W – every atom has eight
neighbors except those on the surface.
b. Face-centered cubic – Cu, Ag, Au, Al, Pb – every atom has
twelve neighbors.
c. Hexagonal close packed – Mg, Cd, Zn – every atom has 12
neighbors but the pattern of arrangement is different .
Alloys
1. Very few objects are pure metals
2. Most metals are alloys
3. Alloys – are mixtures of two or more elements with at least
one element being a metal.
4. Brass – is an alloy of copper and zinc
5. Alloys are important because their properties are often
superior to those of their componetn elements.
6. Sterling silver – 92.5% silver and 7.5% copper
7. Bronze – 7 parts copper 1 part tin
8. Nonferrous alloys – commonly used to make coins – bronze,
copper nickel, aluminum
9. Steel – is one of the most important alloys
10.Principle elements in steel are – Fe, C, B, Cr, Mn, Mo, Ni, W, V
11. Substantial alloys – alloys that form their component atoms in
different ways because the atoms are about the same size
and have the ability of replacing each other.
12.Interstitial alloy – atoms squeeze in between atoms