Metals with Variable Charge Most transition metals (3-12) and Group 4A (14) metals form 2 or more positive ions, except Zn 2+, Ag +, and Cd 2+, which form only one ion. 2013 Pearson Education, Inc. Chapter 5, Section 1 1
Metals with Variable Charge The names of transition metals with two or more positive ions (cations) use a Roman numeral after the name of the metal to identify the ion charge.
Naming Ionic Compounds with Variable Charge Metals
Naming FeCl 2 Step 1 Determine the charge of the cation from the anion. Analyze the Problem.
Naming FeCl 2 Step 2 Name the cation by its element name and use a Roman numeral in parentheses for the charge. Fe 2+ = iron(ii) Step 3 Name the anion by using the first syllable of its element name followed by ide. Cl = chloride Step 4 Write the name for the cation first and the name for the anion second. iron(ii) chloride
Examples of Names of Compounds with Variable Charge Metals 2013 Pearson Education, Inc. Chapter 5, Section 1 6
Writing Formulas for Ionic Compounds
Writing the Formula for Iron(III) Oxide Metal Nonmetal Ion Iron(III) oxide Group Transition 6A (16) Symbol Fe 3+ O 2
Learning Check Write the correct name for CuO. Write the correct formula for copper(i) nitride.
Polyatomic Ions A polyatomic ion is a group of atoms. has an overall ionic charge. Examples: NH + 4 ammonium OH hydroxide SO 2 4 sulfate CO 2 3 carbonate PO 4 3 phosphate
Names and Formulas of Common Polyatomic Ions 2013 Pearson Education, Inc. Chapter 5, Section 1 11
Compounds Containing Polyatomic Ions Polyatomic ions must be associated with an ion of opposite charge. form ionic bonds with ions of opposite charge to achieve charge balance. Example: charge balance: Ca 2+ calcium NO 3 nitrate ion Ca(NO 3 ) 2 calcium nitrate
Name K 2 SO 4 Step 1 Identify the cation and polyatomic ion (anion). Cation: K + Anion: SO 2 4 Step 2 Name the cation, using a Roman numeral if needed. K + = potassium ion Step 3 Name the polyatomic ion. SO 2 4 = sulfate ion Step 4 Write the name or the compound, cation first and the polyatomic ion second. K 2 SO 4 = potassium sulfate
Learning Check Name each of the following compounds. 1. Cu(ClO 3 ) 2 2. PbCO 3 3. Ba 3 (PO 3 ) 2
Solution Step 1 Identify the cation and polyatomic ion (anion). cation polyatomic ion 1. Cu(ClO 3 ) 2 Cu 2+ ClO 3 2. PbCO 3 Pb 2+ CO 2 3 3. Ba 3 (PO 3 ) 2 Ba 2+ PO 3 3 Step 2 Name the cation using a Roman numeral, if necessary. cation name 1. Cu(ClO 3 ) 2 copper(ii) 2. PbCO 3 lead(ii) 3. Ba 3 (PO 3 ) 2 barium
Solution Step 3 Name the polyatomic ion. polyatomic ion 1. Cu(ClO 3 ) 2 chlorate 2. PbCO 3 carbonate 3. Ba 3 (PO 4 ) 2 phosphate Step 4 Write the name or the compound, cation first and the polyatomic ion second. compound name 1. Cu(ClO 3 ) 2 copper(ii) chlorate 2. PbCO 3 lead(ii) carbonate 3. Ba 3 (PO 3 ) 2 barium phosphite
Write the Formula for Aluminium Hydroxide Step 1 Identify the cation and polyatomic ion (anion). Al 3+ and OH Step 2 Balance the charges. Step 3 Write the formula, cation first, using the subscripts from charge balance. Al(OH) 3
Break Time!!
Covalence - Formation of H 2 In the simplest covalent molecule, H 2, the H atoms increase attraction as they move closer. share electrons to achieve a stable configuration. form a covalent bond.
Electron-Dot Formulas of Covalent Molecules In a fluorine (F 2 ) molecule, the F atoms share one of their valence electrons. acquire an octet. form a covalent bond. 2013 Pearson Education, Inc. Chapter 5, Section 1 20
Elements That Exist as Diatomic These seven elements share electrons to form diatomic, covalent molecules. Molecules 2013 Pearson Education, Inc. Chapter 5, Section 1 21
Electron-Dot Formulas for Some Covalent Compounds 2013 Pearson Education, Inc. Chapter 5, Section 1 22
Guide to Drawing Electron-Dot Formulas 2013 Pearson Education, Inc. Chapter 5, Section 1 23
Draw the Electron-Dot Formula for NH 3 Step 1 Determine the arrangement of atoms. In NH 3, N is the central atom and is bonded to three H atoms. Step 2 Determine the total number of valence electrons. H N H H Total valence electrons for NH 3 = 8 e
Draw the Electron-Dot Formula for NH 3 Step 3 Attach each bonded atom to the central atom with a pair of electrons. H N H H
Draw the Electron-Dot Formula for NH 3 Step 4 Place the remaining electrons using single or multiple bonds to complete the octets. 8 valence e 6 bonding e = 2 e remaining Use the remaining 2 e to complete the octet around the N atom. H N H H or H N H H
Learning Check Draw the electron-dot formula for CCl 4. 2013 Pearson Education, Inc. Chapter 5, Section 1 27
Solution Step 1 Determine the arrangement of atoms. In CCl 4, C is the central atom and is bonded to four Cl atoms. Cl Cl C Cl Cl
Solution Step 2 Determine the total number of valence electrons. Total valence electrons for
Solution Step 3 Attach each bonded atom to the central atom with a pair of electrons. Cl Cl C Cl Cl
Solution Step 4 Place the remaining electrons, using single or multiple bonds to complete the octets. 32 valence e 8 bonding e = 24 e remaining Use the remaining 24 e to complete the octets around the Cl atoms. Cl Cl C Cl Cl or Cl Cl C Cl Cl
Single and Multiple Bonds In many covalent compounds, atoms share two or three pairs of electrons to complete their octets. In a single bond, one pair of electrons is shared. In a double bond, two pairs of electrons are shared. In a triple bond, three pairs of electrons are shared.
Draw the Electron-Dot Formula for CS 2 Step 1 Determine the arrangement of atoms. In CS 2, C is the central atom and is bonded to two S atoms. S C S
Draw the Electron-Dot Formula for CS 2 Step 2 Determine the total number of valence electrons. Total valence electrons for
Draw the Electron-Dot Formula for CS 2 Step 3 Attach each bonded atom to the central atom with a pair of electrons. A pair of bonding electrons (single bond) is placed between each S atom and the central C atom. S C S
Draw the Electron-Dot Formula for CS 2 Step 4 Place the remaining electrons using single or multiple bonds to complete the octets. 16 valence e - 4 bonding e = 12 e remaining The remaining 12 electrons are placed as six lone pairs of electrons on both S atoms. However, this does not complete the octet for the C atom. S C S
Draw the Electron-Dot Formula for CS 2 Step 4 Continued: Double and Triple Covalent Bonds: To complete the octet for the C atom, it needs to share an additional lone pair from each of the S atoms, forming a double bond with each S atom. S C S or S C S S C S
A Nitrogen Molecule has a Triple Bond In a nitrogen molecule, N 2, each N atom shares 3 electrons, each N atom attains an octet, and the sharing of 3 sets of electrons is called a triple bond. 2013 Pearson Education, Inc. Chapter 5, Section 1 38