CHEM H90 Lecture Notes - Lecture 10: Ionic Bonding, Octet Rule, Nonmetal

Chemistry 162 Lab Activity



Introduction Water has an amazing ability to adhere (stick) toitself and to other substances. Hydrogen bonds form when hydrogenatoms covalently bonded to nitrogen (N), oxygen (O), or fluorine(F) in the form of covalent compounds such as ammonia (NH3), water(H2O) and hydrogen fluoride gas (HF). In these molecules, thehydrogen atoms do not pull as strongly on the shared electrons asthe N, O, or F atoms. Therefore, the molecules are polar; thehydrogen atoms become positively charged and are able to formhydrogen bonds to negative ions or negatively charged parts ofother molecules (such as the N, O, and F atoms that becomenegatively charged in these compounds). Hydrogen bonds are not truebonds like covalent bonds or ionic bonds. Hydrogen bonds areattractions of electrostatic force caused by the difference incharge between slightly positive hydrogen ions and other, slightlynegative ions. These attractions are much weaker than true ionic orcovalent bonds, but they are strong enough to result in someinteresting properties.

In the case of water, hydrogen bonds form between neighboringhydrogen and oxygen atoms of adjacent water molecules. Theattraction between individual water molecules creates a bond knownas a hydrogen bond (Fig. 1).
Fig. 1: Hydrogen bonds shown as the dotted lines between watermolecules.
Cohesion Molecules of pure substances are attracted to themselves.This sticking together of like substances is called cohesion.Depending on how attracted molecules of the same substance are toone another, the substance will be more or less cohesive. Hydrogenbonds cause water to be exceptionally attracted to each other.Therefore, water is very cohesive.
Adhesion Adhesion is similar to cohesion, but it involves unlike(i.e. different) substances sticking together. Water is veryadhesive; it sticks well to a variety of different substances.Water sticks to other things for the same reason it sticks toitself – because it is polar so it is attracted to substances thathave charges. In this lab activity, you will be asked to use thematerials and procedures provided to explore the properties ofwater that involve both cohesion and adhesion. Be sure to writedown your observations and results as you progress. sults as youprogress.

Fig. 1

:

Hydrogen bonds shown as the dotted

lines between water molecules.

Part 1:

Exploring Water

Procedure

A.

How many drops of water can you fit on the surface of a pennywithout the water spilling over?

1.

Predict how many drops of water will fit on a penny. Record yourprediction.

2.

Use the plastic pipette to drop water on the surface of a penny.Drop car

efully and slowly to fit as

many drops as possible on the penny. Count each drop until thewater spills over the side of the

penny and record your results.

3.

Compare your results to those of your classmates. Record therange and calculate the average

number

of drops that fit on a penny.

4.

Add more drops to the penny, without letting the water spillover. Carefully observe and draw the

water on the penny.

5.

Record

a hypothesis for the behavior of water that you observed, usingthe language of cohesion

and adhesion

in relation to the water and the penny.

A.

Record your results and

thinking in your notebook.

B.

Can you

disturb

the water on the penny without spilling it?

1.

A

dd drops of water to the penny, until the water is almost readyto spill over.

2.

Predict what will

happen when you insert a toothpick into the surface of the waterpiled on the

penny. Record your prediction.

3.

Insert the

toothpick

and carefully observe the surface of the water.

4.

Try inserting the

toothpick

in various ways. Observe the surface of the water.

Pay special attention to

the water surface where the skewer enters the water.

5.

Record your observations and draw what you see.

6.

Repeat

these

procedures using a paper clip and the metal clip part of abinder clip. Try to indent the

pile of water as much as p

ossible without spilling it.

7.

Record your observations and dra

w what you see, paying careful

attention to the surface of the

water.

8.

Record

a hypothesis for the behavior of water that you observed usingthe language of cohesion

and adhesion in relation to the

toothpick

, the paperclip, the binder clip, and the water.

B.

Record your results and

thinking in your notebook.would you please answer the questionfor me . Thanks

Nomenclature lab : will rate answer

Nomenclature lab: will choose best answr

Type I Binary Ionic Compounds

Type I binary ionic compounds contain a metal and a nonmetal AND the metal that is present only forms one type of cation. Metals with only one cation(shaded below with charges). Both the metal and the nonmetal form ions, which is why it is called an ionic compound.

From the following list, cross out those compounds that do NOT belong in the category for Type I binary ionic compounds.

NaCl FeCl2 CaCl2 TiO2 MgO AlBr3 KCl K2S BeF2 Cu2O3 AgCl Zn3N2

Formula and name examples for Type I binary ionic compounds:

KI = potassium iodide BaO = barium oxide ZnF2 = zinc fluoride Na2S = sodium sulfide

Ag3N = silver nitride BeCl2 = beryllium chloride

What type of element is always listed first (metal or nonmetal)? ____________ second? ___________

Is the name of the first element in the compound different from the element? (yes/no)

What is the common ending for all the names? ______________

In zinc fluoride, there are 2 fluoride atoms, are they indicated in the name? (yes/no)

What is the charge on the zinc ion? _______

What is the charge on the fluoride ion? _______

Why do you need one zinc ion and two fluoride ions for the formula for zinc fluoride?

Why do you need two sodium ions for every sulfide ion in sodium sulfide?

Try not to look in your book and determine the rules for naming type I binary ionic compound when given the formula.

Try not to look in your book and determine the rules for writing the formula for a type I binary compound when given the name.

Name each of the type I binary ionic compounds listed in Question 1 of the Type I section in words.

Type II Binary Ionic Compounds

Type II binary ionic compounds also contain a metal and a nonmetal however the metal that is present here can form more than one type of cation. Metals with multiple possible charges are listed in the periodic table as blank. Type II metals are NOT Type I metals. Again, both the metal and the nonmetal form ions, and it is still called an ionic compound. These metals usually only form two different ions.

From the following list, cross out those compounds that do NOT belong in the category for Type II binary ionic compounds.

AlP FeCl2 Ag2O VBr5 CoS SnF2 K3N SrF2 CuBr AuCl3 ZnO HgS

Formula and name examples for Type II binary ionic compounds:

Fe2O3 = iron(III) oxide or ferric oxide FeO = iron(II) oxide or ferrous oxide

CuS = copper(II) sulfide or cupric sulfide CuCl = copper(I) chloride or cuprous chloride

MnO2 = manganese(IV) oxide or manganic oxide MnCl2 = manganese(II) chloride or manganous chloride

What type of element is always listed first (metal or nonmetal)? ____________ second? ___________

Is the name of the first element in the compound different from the element? (yes/no)

What is the common ending for the nonmetal portion of the names? ______________

In the compound FeO, what is the charge on iron? _______

In the compound Fe2O3, what is the charge on iron? ________

What does the Roman number after the metal name represent?

Try not to look in your book and determine the rules for naming type II binary ionic compound when given the formula.

Try not to look in your book and determine the rules for writing the formula for a type II binary compound when given the name.

Name each of the type II binary ionic compounds listed in Question 1 of the Type II section in words.

Type III (Nonmetallic) Binary Compounds

Binary compounds that do not contain metals, sometimes referred to as binary molecular compounds, have covalent bonds instead of ionic bonds. A covalent bond is formed by sharing one or more pairs of electrons. The pair of electrons is shared by both atoms. For example, in forming H2, each hydrogen atom contributes one electron to the single bond.

From the following list, cross out those compounds that do NOT belong in the category for binary compounds containing only nonmetals or metalloids.

CCl4 AlCl3 CO SeF6 SiO2 SrI2 P4O10 TiO2 SeO3 IrCl ZrO2 N2O5

Formula and name examples for Type III binary molecular compounds:

CO2 = carbon dioxide H2O = dihydrogen monoxide

IF5 = iodine pentafluoride BF3 = boron trifluoride

Which element is listed first in the name?

Is the name of the first element in the compound different from the element? (yes/no)

What is the common ending for all the names? ______________

What do the prefixes (di-, mono-, penta-, tri-) in the names above mean?

Is the prefix mono- used when there is only one atom of the first element? (yes/no)

Is the prefix mono- used when there is one atom of the second element? (yes/no)

Try not to look at your book and determine the rules for naming type III binary ionic compound when given the formula.

Name each of the type III binary compounds in Question 1 of the Type III section in words.

Compounds Containing Polyatomic Ions

Polyatomic ions are ions that as a group have a set charge. Polyatomic ions are usually recognized in a formula by the grouping of more than one nonmetal elements after a metal. Your book has a table listing polyatomic ions. Use your book’s table to fill in the following table with the appropriate names/formulas of the polyatomic ions.

Polyatomic ions containing oxygen (oxyanions or oxoanions) are somewhat special.

carbonate = CO3-2

Match the location of carbon on the periodic table with the two figures on the right.

What number is in the carbon location on the left figure? To what does this number refer?

What number is the carbon location on the right figure? To what does this number refer?

What element must all oxyanions contain?

What is the ending of the name of the ion determined from these tables?

Determine the formula for the following oxyanions using the figures above. Phosphate _________ Silicate ________ Bromate ________ Iodate ________ Sulfate ________ Nitrate ________

Review Table

Use your knowledge of Type I and Type II metals as well as the appropriate polyatomic name/formula to fill in the following table.

Acids

Acids are compounds that when dissolved in water, produce hydrogen ions (H+). Naming acids can be tricky. Use the following figure to determine how to name an acid.

FG02_27

Given that the ion formula is NO2-1, how can one determine the name of the ion, acid formula, and acid name?

Ion name:

What is the formula for nitrate?

Is NO2-1 the nitrate ion or the nitrite ion?

Acid formula:

According to the figure above, what ion must be added to create an acid? What is the charge of that ion?

How many of the hydrogen ions must be added to NO2-1 to make a neutral acid (zero charge)?

What is the chemical formula for the acid created when hydrogen ion(s) are added to NO2-1?

Acid name:

Based on your answer to Question 1 above, does the name for the NO2-1 ion end in –ite or –ate?

Name the acid, HNO2.

Fill in the following acid table: