ionic and metallic bonding and nomenclature Unit Exam Review

FeO

iron (II) oxide

AgNO3

silver nitrate

Na2S

sodium sulfide

aluminum bromide

AlBr3

Describe the difference between the metal alloy sterling silver and carbon steel in terms of the types of alloys involved.

Alloys are mixtures of different types of metals. A substitutional alloy is created when metals of similar size are mixed together: some of the base metal atoms are literally substituted or replaced in the metallic lattice by the other metal atoms. Sterling silver is an example of this - Ag with Cu atoms substituted. An interstitial (between spaces) alloy is created when metals of different sizes are mixed together: none of the base metal atoms are replaced, but some of the other atoms add into the spaces between the base metal atoms in the metallic lattice. Carbon steel is an example of this. Fe atoms with C in the spaces.

Barium hydroxide

Ba(OH)2

cobalt (III) phosphate

CoPO4

Explain how an ionic bond is different from a metallic bond.

In ionic bonds a highly electronegative non-metal strips electrons from a low ionization energy metal creating a metal cation and a nonmetal anion. The bond is the coulombic (electrostatic) attractive force between these two ions. An ionic lattice is made of alternating cations and anions. Metallic bonds form when loosely held valence electrons become delocalized forming a "Sea of Electrons" which are not fixed to a certain atom. These electrons are free to move contributing to the properties of metals such as conductivity and malleability. The bonds is the coulombic (electrostatic) attractive force between metal cations and delocalized valence electrons. A metallic lattice is made of metal cations with a sea of electrons moving among them.

In number 5, which compound contains an element with a +2 charge?

Iron (II) oxide

KCl has a lower melting point than LiCl.

KCl has a lower melting point than LiCl because the lattice energy of KCl is less than the lattice energy of LiCl. Coulomb's law determines how high the lattice energy is. KCl has K+ and Cl- ions, and LiCl has Li+ and Cl- ions. Both have the same magnitude of charge so this is not effective the difference in coulombic attraction. However, since the potassium ion is larger that the Lithium ion, the ions in KCl are a further distance apart than in the ions in LiCl. Therefore, there is LESS coulombic attraction in the KCl lattice making a LOWER lattice energy in KCl than LiCl. Therefore, it takes less energy to melt KCl.

Li and O

Li2O lithium oxide

Considering electronegativity and ionization energy across the periodic table, how do metals and nonmetals complement each other in an ionic bond?

Metals generally have lower ionization energy and electronegativity values, meaning metals have a weak ability to attract electrons and relatively little energy is required to remove an electron from a metal. Nonmetals generally have higher ionization energy and electronegativity values, meaning nonmetals have a strong ability to attract electrons and higher amounts of energy are required to remove electrons from a nonmetal. Therefore, both metals and nonmetals become more stable when the metal gives off its valence electrons and the nonmetal accepts them in an ionic bond.

Mg and ClO-1

Mg(ClO)2 magnesium hypochlorite

Mn+4 and F

MnF4 manganese (IV) fluoride

In Number 5, assume all are soluble in water. Which one would be the strongest electrolyte? Justify your answer.

Na2S would be the strongest electrolyte because it forms 3 ions when dissolved. Both iron (II) oxide and silver nitrate only form 2 ions when dissolved. The more ions formed in solution will cause the solution to conduct electricity better.

Ni+3 and SO3-2

Ni2(CO3)3 nickel (III) carbonate

Sr and O

SrO Strontium oxide

Explain how the conductivity of electricity and the high boiling point of metals is explained by metallic bonding. Include a picture of metallic bonding to better clarify your explanation.

Conductivity - Metals conduct electricity due the delocalized electrons present in the bonding. When an electric current is applied to a metal, the electrons are free to move and conduct the current. High Boiling Point - Metals have high melting and boiling points because they are held together with strong electrostatic (coulombic) attractions between the metal cations and the delocalized valence electrons.

Copper (I) sulfate is commonly used to prevent algae growth in ponds. If 225 g of copper (I) sulfate is added to a pond, answer the following questions. Write the cation for the chemical compound. Write the anion for the chemical compound. White the chemical formula for copper (I) sulfate.

Cu+ SO42- Cu2SO4

CaCl2 has a higher melting point than LiCl.

The CaCl2 ionic compound is composed of a formula unit of 1 Ca+2 ion and 2 Cl- ions. The LiCl ionic compound is composed of a formula unit of 1 Li+ ion and 1 Cl- ion. Melting an ionic compound involves separating the component ions. According to Coulomb's Law, attraction between charges increases as the size of charge increases. The CaCl2 compound includes a larger size charge than the LiCl compound, therefore CaCl2 is more strongly bonded than LiCl. The stronger the bond, the more energy is required to separate the ions, the higher the melting point.

Explain why the term delocalized is appropriate for the electrons involved in metallic bonding.

The valence electrons in a metal are not fixed to a certain metal cation. They are shared equally around all metal cations and free to move. Since they are not fixed to a certain location, they are called "delocalized."

When metals and nonmetals form an ionic bond, which type of ion does each atom form?

When metals give away valence electrons, they become positively-charged cations. When nonmetals take on more valence electrons, they become negatively-charged anions.