Ionic Compounds and Metals

Ionic Compounds and Metals
Chapter 7 - Ionic Compounds & Metals Ionic Compounds and Metals \ Chapter 7

Chapter 7 - Ionic Compounds & Metals
Vocabulary Ch. 7.2 Ionic bond Ionic compound Binary compound Crystal lattice Electrolyte Lattice energy Ch. 7.1 Chemical bond Cation Anion

Objectives Define a chemical bond Describe how ions form Identify ionic bonding and the characteristics of ionic compounds Name and write formulas for binary compounds Polyatomic ion containing compounds Compound with metals that have multiple oxidation states Hydrates

Forming Compounds The Octet Rule: Atoms become stable by having 8 electrons in their outer energy level (2 for smaller atoms) Similar arrangement of valence electrons for element in the same group. (Ex: ns1 for alkali metals) Electron arrangements determines chemical properties Presents a model of chemical stability When they have gotten 8 electrons they have achieved NOBLE GAS CONFIGURATION

Forming Compounds atoms collide with enough energy outer electrons move to achieve a stable octet of valence electrons (noble gas configuration). atoms formed a new compound Total # of e- must remain the same. Electrons are particles of matter.

Forming Compounds Transfer of Electrons Na· + ·Cl:  [Na]+ + [:Cl:]- ˙˙ ˙˙

Lattice Energy Ionic compounds consist of a crystal lattice of positive and negative ions, which is a repeating pattern of ions. = Na+ = Cl-

Lattice Energy The lattice energy is the energy required to separate the ions from their crystalline solid state. Increases with decreasing ionic size. Increases with increasing ionic charge.

Lattice energy decreases as anion gets bigger!! Lattice energy is large due to +2 and -2 Charges; decreases as ions get larger.

Lattice Energy Physical Properties of ionic compounds: The melting point increases as lattice energy increases. Solutions are electrolytes, which conduct an electric current. Force applied to crystals causes them to shatter.

Vocabulary Ch. 7.3 Formula Unit Monoatomic ion Oxidation Number Polyatomic ion

Names and Formulas Rules for naming binary compounds Name the cation first. This is usually a metal. Use element name. Then name the anion using the 1st syllable of the of the element name and then end in –ide. Example: Potassium Chloride (KCl) Magnesium Oxide (MgO)

Binary Compound Naming Practice
Chapter 7 - Ionic Compounds & Metals Binary Compound Naming Practice Formula NaF Al2S3 CaO Mg3N2 CaH2 Name

Predicting Charge on Ions
Chapter 7 - Ionic Compounds & Metals Predicting Charge on Ions Can you predict the charge on an ion depending on where it is in the periodic table? Yes, of course. Group numbers can help predict many charges. For groups 1 & 2 – they lose electrons and become positive Group 13 – loses 3 electrons and are generally positive Groups 15 – 17 gain electrons and become negative in ions.

Predicting Charge on Ions
Chapter 7 - Ionic Compounds & Metals Predicting Charge on Ions The charge on a monoatomic ion is the Oxidation number Again, oxidation number for many elements in the main group (Groups 1 & 2, 13-18) can be predicted by looking at the group number.

Rules For Writing Ionic Compound Formulas
Chapter 7 - Ionic Compounds & Metals Rules For Writing Ionic Compound Formulas Write cation symbol first. (Same as we did in naming them.) Write anion symbol second. Add subscripts such that the sum of the charges is zero. Write the simplest ratio of ions. This is the formula unit. Write cation and anion in symbol form.

Writing Ionic Formula Example: What is the formula for Aluminum Oxide? What is charge on aluminum when it is an ion? What is charge on oxygen when it is an ion (oxide)? How do we get the charges to balance?

Method of “Cross-Multiplying”
Chapter 7 - Ionic Compounds & Metals Method of “Cross-Multiplying” What would be the subscripts to make the Sum = 0? Drop the signs and make the numbers subscripts Use it backward—knowing compound Figure out charges

Examples of Writing Formulas (Binary Compounds)
Chapter 7 - Ionic Compounds & Metals Examples of Writing Formulas (Binary Compounds) Name of Compound Formula of Compound Lithium oxide Lithium ions and oxide ions Li O2- Calcium chloride Calcium ions and chloride ions Ca Cl- Magnesium nitride magnesium ions and nitride ions Mg N3-

Practice Writing Binary Compound Formulas
Chapter 7 - Ionic Compounds & Metals Practice Writing Binary Compound Formulas Name of Compound Formula of Compound Lithium iodide Beryllium chloride Calcium oxide Sodium oxide Strontium sulfide Calcium phosphide

Compounds of Metals with Multiple Oxidation States (Multivalent Metals) Includes metals in Groups 3 through 12 of the periodic table And the representative metals in Groups 13 & 14 (Commonly Sn & Pb, but also Ga, In, and Tl) They have more than one Oxidation State So they can form more than one type of positive ion.

Compounds of Multivalent Metals
Chapter 7 - Ionic Compounds & Metals Compounds of Multivalent Metals For Example: Copper can exist as Cu+ and Cu2+ Iron can exist as Fe2+ and Fe3+ Exceptions: Zn and Ag. Zinc only forms a Zn2+ ion Ag only forms a Ag+ ion

Chapter 7 - Ionic Compounds & Metals Compounds of Multivalent Metals How do chemists distinguish the names of compounds formed these metals? We use Roman numerals in parenthesis after the name of the element. Copper Ion Chloride Ion Formula Name Cu+ Cl- CuCl Copper (I) Chloride Cu2+ 2Cl- CuCl2 Copper (II) Chloride

Chapter 7 - Ionic Compounds & Metals Compounds of Multivalent Metals These don’t show all the ions, just the most common ones.

Chapter 7 - Ionic Compounds & Metals Compounds of Multivalent Metals The red dots show the common oxidation states. The white ones are less common.

Formulas of Multivalent Metals
Chapter 7 - Ionic Compounds & Metals Formulas of Multivalent Metals How to write a formula containing one of these metals. First, look at the name. Example: if it is Manganese (III) it means that it’s Mn3+ The roman numeral is the oxidation number of the ion, not how many there are!!!! Then, you can balance charges as before. Example: MnCl3 Manganese is 3+ and chloride is always 1-.

Writing Names of Multivalent Metal Compounds
Chapter 7 - Ionic Compounds & Metals Writing Names of Multivalent Metal Compounds If your given a formula, how do you figure out the name? Determine the charge on the metal ion. Look at the negative ion. Figure out what was needed to make the compound neutral Example: FeCl3

Chapter 7 - Ionic Compounds & Metals Compounds of Multivalent Metals Given name or formula Determine formula or name Iron(II) oxide MnF3 Nickel(II) chloride PbS2

What is the oxidation number of Zinc when it’s an ion?
Chapter 7 - Ionic Compounds & Metals What is the oxidation number of Zinc when it’s an ion? 1+ or 2+ 2+ always 1+ always 1- or 2-

What is the formula for iron(II) oxide?
Chapter 7 - Ionic Compounds & Metals What is the formula for iron(II) oxide? Fe2O FeO2 Fe2O2 FeO

What is the correct name of MnF3?
Chapter 7 - Ionic Compounds & Metals What is the correct name of MnF3? Manganese (I) fluoride Magnesium (I) fluoride Manganese (III) fluoride Magnesium (III) fluoride

What is the correct formula for nickel(II) chloride?
Chapter 7 - Ionic Compounds & Metals What is the correct formula for nickel(II) chloride? Ni2Cl NiC2 NiCl2 Ni2Cl2 C

What is the name of PbS2? Lead (IV) sulfide Lead (I) sulfide Lead (II) sulfide Lead (III) sulfide

Polyatomic Ions Ions can contain more than one element. An ion with two or more different elements is a Polyatomic Ion In polyatomic ions, the atoms are covalently bonded and the atoms share electrons. Individual atoms have no charge, but the group has an overall charge. Example: SO42- (Sulfate)

Common Polyatomic Ions
Chapter 7 - Ionic Compounds & Metals Common Polyatomic Ions Name of Ion Formula Charge Ammonium NH4+ 1+ Hydrogen carbonate (bicarbonate) HCO3- 1- Hydrogen sulfate HSO4- Acetate C2H3O2- Nitrite NO2- Nitrate NO3- Cyanide CN- Hydroxide OH-

Common Polyatomic Ions
Chapter 7 - Ionic Compounds & Metals Common Polyatomic Ions Name of Ion Formula Charge Dihydrogen phosphate H2PO4- 1- Permanganate MnO4- Carbonate CO32- 2- Sulfate SO42- Sulfite SO32- Oxalate C2O42- Monohydrogen phosphate HPO42- Dichromate Cr2O72- Phosphate PO43- 3-

Compounds Containing Polyatomic Ions
Chapter 7 - Ionic Compounds & Metals Compounds Containing Polyatomic Ions When there is more than one polyatomic ion, treat it as if it were a single ion by keeping it together as a unit using parenthesis. Write a subscript outside the parenthesis to show how many units there are of polyatomic ion. Remember that the sum of the charges must equal zero.

Examples of Writing Formulas (w/Polyatomic Ions)
Chapter 7 - Ionic Compounds & Metals Examples of Writing Formulas (w/Polyatomic Ions) Name of Compound Formula of Compound Calcium nitrate Calcium ions and nitrate ions Ca NO31- Sodium carbonate Sodium ions and carbonate ions Na CO32- Lead(II) Phosphate lead 2+ ions and phosphate ions Pb PO43-

Naming Polyatomic Compounds from formulas
Chapter 7 - Ionic Compounds & Metals Naming Polyatomic Compounds from formulas Positive ion (usually a metal) is named first as before. Negative polyatomic ion name as listed in the chart is second. Note: If you see more than one element after the metal the rest is a polyatomic ion. Look for that group in the chart.

Polyatomic Ion Practice
Chapter 7 - Ionic Compounds & Metals Polyatomic Ion Practice Given name or formula: NaHCO3 Lithium Acetate Ca(CN)2 Copper(II) Hydroxide K2Cr2O7 Fe(HCO3)3 Ammonium Chloride Determine formula or name

What is the formula for zinc arsenate?
Chapter 7 - Ionic Compounds & Metals What is the formula for zinc arsenate? Note: You have to type this in. Hit the ‘Shift’ key (lower right) to get capital letters. If you need parenthesis, hit sym 4 for ‘(‘ and sym 5 for ‘)’.

Ch. 7.4 Vocabulary Ch. 10.5 Ch. 7.4 Hydrate (page 351) Electron Sea model Delocalized electron Metallic Bond Alloy Interstitial alloy Substitutional Alloy

Compounds of Hydrates (Ch. 10.5)
Chapter 7 - Ionic Compounds & Metals Compounds of Hydrates (Ch. 10.5) Hydrate – when there is a specific amount of water in the crystal of a compound. The water molecules are part of the crystal structure of the ionic compound. Many compounds become hydrates by absorbing water from the air. The water then becomes part of its structure. Many of them are used as drying agents (desiccants).

Compounds of Hydrates When writing a formula for a hydrated compound use a dot (•) followed by the number of water molecules. Example: CaCl2•2H2O This means that this hydrated chloride compound has 2 molecules of water for each formula unit of calcium chloride.

CaCl2•2H2O Water - Cl- Cl- Ca+2 Cl- - Water

Compounds of Hydrates CaCl2•2H2O This means that this hydrated chloride compound has 2 molecules of water for each formula unit of calcium chloride. You would call the compound Calcium chloride dihydrate. Rule: Follow the regular name of the compound with the word “hydrate.” The prefix before “hydrate” tells you how many water molecules there are.

Prefixes for Hydrates Molecules of Water Prefix 1 Mono- 2 Di- 3 Tri- 4 Tetra- 5 Penta- 6 Hexa- 7 Hepta- 8 Octa- 9 Nona- 10 Deca-

Hydrate Compound Practice
Chapter 7 - Ionic Compounds & Metals Hydrate Compound Practice Given Name or Formula Determine the Formula or Name MgSO3•6H2O Strontium oxalate monohydrate Ni3(PO4)2•7H2O Lead(II) acetate trihydrate

Compounds of Hydrates Hydrates can also lose water molecules, usually by heating. They may even have a different color than the hydrated compound. When they lose their water molecules, they become anhydrous (without water).

Ch. 7.4 - Metal Bonding – Electron Sea Model
Chapter 7 - Ionic Compounds & Metals Ch Metal Bonding – Electron Sea Model There are not enough electrons for the metal atoms to be covalently bonded to each other. We use a delocalized model for electrons in a metal

Delocalized Electrons in a Metal
Chapter 7 - Ionic Compounds & Metals Delocalized Electrons in a Metal The metal nuclei are seen to exist in a sea of electrons. No electrons are localized between any two metal atoms. Therefore, the electrons can flow freely through the metal. Without any definite bonds, the metals are easy to deform (and are malleable and ductile). The more delocalized e-, the harder and stronger the metal.

Delocalized Model for Electrons in a Metal

Melting Point

Malleability Metals, above, compared to ionic compounds, below.

Alloys Alloys are homogeneous mixtures, metal solutions, really. Substitutional alloys: atoms must have similar atomic size, elements must have similar bonding characteristics. Interstitial alloys: one element much smaller than the other in order to fit into the interstitial sites, e.g. a nonmetal. The alloy is much stronger than the pure metal (increased bonding between nonmetal and metal). Example steel (contains up to 3% carbon).

Alloys

Common Alloys Chapter 7 - Ionic Compounds & Metals

Ionic Compounds and Metals

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