Sec 6.3 Naming Compounds and Writing Formulas Key Concepts: What information do the name and formula of an ionic compound provide? What information do the name and formula of a molecular compound provide? Vocabulary: Polyatomic Ion

Describing Ionic Compounds Page 170 – Thomas Drummond and lime The name of an ionic compound must distinguish the compound from other ionic compounds containing the same elements. The formula of an ionic compound describes the ratio of ions in the compound.

Binary Ionic Compounds A compound made from only two elements is a binary compound. Name of cation followed by the name of the anion Remember: cations do not change their names – name of the original metal atom Anions use part of the name of the nonmetal atom but change the suffix to –ide. (see Common Anions, Figure 16 on page 171)

Metals with multiple ions The alkali metals, alkaline earth metals, and aluminum for ions with a positive charges equal to the group number. The transition metals form more than one type of ion – resulting in metals with multiple ions When a metal forms more than one charge, a Roman numeral is used to indicate the charge (See Some Metal Cations, figure 17, page 172)

Writing Formulas for Ionic Compounds If you know the name, you can easily write the formulas. Place the symbol of the cation first, followed by the symbol of the anion. Use subscripts to show the ratio of the ions in the compound. Because all compounds are neutral, the total charges on the cations and anions must add up to zero.

Describing Molecular Compounds The name and formula of a molecular compound describe the type and number of atoms in a molecule of the compound.

Naming Molecular Compounds The general rule is that the most metallic element appears first in the name. These elements are farther to the left in the periodic table. If two elements are in the same group, the elements that is closer to the bottom of the group is more metallic. The name of the second element is changed to end in the suffix –ide.

Naming Molecular Compounds When naming molecular compounds, their names reflect the number of each atom present through the use of Greek prefixes (see Prefixes for Naming Compounds, figure 20, page 175)

Writing Molecular Formulas Writing the formulas for a molecular compound is easy! Write the symbols for the elements in order the elements appear in the name. The prefixes indicate the number of atoms of each element in the molecule. These should appear as subscripts in the formula If there is no prefix for an element in the name (specifically the first element), there is only one atom of that element in the molecule.

Sec 6.4 The Structure of Metals Key Concepts What are the forces that give a metal its structure as a solid? How do metallic bonds produce some of the typical properties of metals? How are the properties of alloys controlled? Vocabulary: Metallic bond Alloy

Metallic Bonds Metal atoms achieve stable electron configurations by losing electrons. But what happens if there are no nonmetal atoms available to accept the electrons? In a metal, valence electrons are free to move among the atoms. In effect, the metal atoms become cations surrounded by a pool of shared electrons. A metallic bond is the attraction between a metal cation and the shared electrons that surround it.

Metallic bonds The cations in a metal form a lattice that is held in place by strong metallic bonds between the cations and the surrounding valence electrons. Although the electrons are moving, the total number of electrons does not change – the metal remains neutral.

Metallic Bonds The metallic bonds in some metals are stronger than in other metals. The more valence electrons an atom can contribute to the shared pool, the stronger the metallic bonds will be. The bonds in an alkali metal are relatively weak because they only contribute 1 valence electron. Metals that contribute more electrons are harder and have higher melting points (sodium vs tungsten)

Explaining Properties of Metals The mobility of electrons within a metal lattice explains some of the properties of metals. The ability to conduct an electric current and malleability are two important properties of metals. A metal has a built-in supply of charged particles that can flow from one location to another – pool of shared electrons An electric current can be carried through the metal by the free flow of the shared electrons.

Explaining Properties of Metals The lattice in a metal is flexible compared to the rigid lattice in an ionic compound. The metal ions can shift their positions and the shape of the metal can change Malleability/ductility can be explained by the bonding between the cations and the pool of electrons in a metal.

Alloys An alloy is a mixture of two or more elements, at least one of which is a metal. Alloys have the characteristic properties of metals A few types of alloys include: Gold Alloys Copper Alloys Steel Alloys

Gold Alloys When gold is 100% pure is 24 karat 18 karat gold is 75% gold 12 karat gold is 50% gold When silver, copper, nickel, or zinc is mixed with gold, the gold is harder and more resistant to wear.

Copper Alloys The first important alloy was bronze, whose name is associated with an important era in history – the Bronze Age Metalworkers in Thailand may have been the first to make bronze. Sometimes the properties of bronze was not always the same – the difference could be traced to the presence of tin.

Copper Alloys In its simplest form, bronze contains only copper and tin – which are relatively soft metals. Mixed together in bronze, the metals are much harder and stronger than either metal alone. Scientists can design alloys with specific properties by varying the types and amounts of elements in an alloy.

Copper Alloys Brass is another alloy of copper that has been known for centuries. In its simplest form, brass contains only copper and zinc. Brass and bronze have completely different properties (page180)

Steel Alloys Steel is an alloy of iron that contains small amounts of carbon – ranging from 0.2% to about 3% by mass. The smaller carbon atoms fit in the spaces between the larger iron atoms in the lattice. Carbon forms bonds with the neighboring iron atoms that make the lattice harder and stronger than iron alone.

Steel Alloys The properties of any particular type of steel depend on which elements other than iron and carbon are used and hoe much of those elements are included Stainless steel – contains chromium, but almost no carbon – durable and prevents rusting Strong steel (used in bridge cables) – containts C, S, Mn, P, Si, and 0.81%C – makes them strong and resists forces that can cause the wire to stretch or break.

Other Alloys Aluminum alloys – if a small amount of Cu or Mn is added to Al, the result is a stronger material that is still lighter than steel. Al and Mg alloys – keeps advantages of Mg (less dense that most metals used to build structures) but loses all of the disadvantages (soft enough to cut with a knife and burns in air)