Metals with Variable Charge

Transcription

1 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 Pearson Education, Inc. Chapter 5, Section 1 1

2 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.

3 Naming Ionic Compounds with Variable Charge Metals

4 Naming FeCl 2 Step 1 Determine the charge of the cation from the anion. Analyze the Problem.

5 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

6 Examples of Names of Compounds with Variable Charge Metals 2013 Pearson Education, Inc. Chapter 5, Section 1 6

7 Writing Formulas for Ionic Compounds

8 Writing the Formula for Iron(III) Oxide Metal Nonmetal Ion Iron(III) oxide Group Transition 6A (16) Symbol Fe 3+ O 2

9 Learning Check Write the correct name for CuO. Write the correct formula for copper(i) nitride.

10 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

11 Names and Formulas of Common Polyatomic Ions 2013 Pearson Education, Inc. Chapter 5, Section 1 11

12 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

13 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

14 Learning Check Name each of the following compounds. 1. Cu(ClO 3 ) 2 2. PbCO 3 3. Ba 3 (PO 3 ) 2

15 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 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

16 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

17 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

18 Break Time!!

19 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.

20 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 Pearson Education, Inc. Chapter 5, Section 1 20

21 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

22 Electron-Dot Formulas for Some Covalent Compounds 2013 Pearson Education, Inc. Chapter 5, Section 1 22

23 Guide to Drawing Electron-Dot Formulas 2013 Pearson Education, Inc. Chapter 5, Section 1 23

24 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

25 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

26 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

27 Learning Check Draw the electron-dot formula for CCl Pearson Education, Inc. Chapter 5, Section 1 27

28 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

29 Solution Step 2 Determine the total number of valence electrons. Total valence electrons for

30 Solution Step 3 Attach each bonded atom to the central atom with a pair of electrons. Cl Cl C Cl Cl

31 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

32 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.

33 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

34 Draw the Electron-Dot Formula for CS 2 Step 2 Determine the total number of valence electrons. Total valence electrons for

35 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

36 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

37 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

38 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 Pearson Education, Inc. Chapter 5, Section 1 38