UNIT 4: Bonding CHEMICAL BONDS A. Definition: B. Bonds form from the attraction between 1., or 2.. C. REVIEW 1. What part of the atom is involved in bonding? 2. Atoms bond to. What makes an atom stable?! Practice: 3. The rule guides atoms in bonding. This rule states that. Label the parts of the Lewis dot structure below.! Practice: Draw Lewis dot diagrams for the atoms shown below. 1A 2A 3A 4A 5A 6A 7A 8A H He Li Be...... B C N O F Ne Na Mg...... Al Si P S Cl Ar Bonding (Chapters 8, 9) Page 1
TYPES OF BONDS A. Covalent Bonds 1. Definition: 2. Covalent bonding forms compounds known as. Multiple covalent bonds may form between the. a. One pair of shared electrons forms a. b. Two pairs of electrons shared between two atoms form a. c. Three pairs of electrons shared between two nonmetal atoms form a. 3. The shared electrons complete the ; both atoms become stable by. 4. are formed when two atoms of the same element share electrons to form a covalently bonded molecule. exist in nature as, not as individual atoms. 2 2 2 2 2 2 2 B. Ionic Bonds 1. Definition: 2. Ionic bonds form because of the, resulting from the of electrons from to. a. Two monatomic ions a metallic cation and a nonmetallic anion combine to form a. b. are formed when a is involved as either the cation or, more often, as the anion. Formula unit: Bonding (Chapters 8, 9) Page 2
FORMATION OF IONS! Practice: A. Metals electrons to become. B. Nonmetals electrons to become. C. Ions may be or. 1. 2. ; the unit acts as an individual ion and the. The most commonly used polyatomic ions are listed on the back side of your copies of the Periodic Table. D. equals the number of electrons transferred from an atom to form its ion and is ; oxidation number is predicted by the. E. Transition elements and metals under the stairs have. These elements usually form ions with. Where are oxidation numbers found on the periodic table? Fill in the table below with the appropriate oxidation numbers. Group 1A 2A 3A 4A 5A 6A 7A Oxidation Number Explain why metals have positive oxidation numbers while oxidation numbers for nonmetals are negative. Bonding (Chapters 8, 9) Page 3
Explain why noble gases are assigned an oxidation number of 0. FORMATION OF IONIC COMPOUNDS A. Lewis dot structures can be used to show the formation of ions and ionic compounds. 1. Sodium loses one electron to become a cation while chlorine gains one electron to become an anion. Na Na + e Cl + e Cl 2. The electron lost by sodium may be transferred to chlorine. 3. The attraction between the opposite charges of the sodium ion and the chloride ion result in the ionic compound sodium chloride. B. Ionic Compounds (AKA ) 1. The overall charge on one unit of an ionic compound is. The number of electrons must equal the number of electrons. are used to help determine the necessary to form a. 2. Binary Ionic Compounds a. Determine the of the ions involved from their. For example, K O Bonding (Chapters 8, 9) Page 4
b. Combine ions so that. All compounds are neutral! For example, charges ( ) are needed to balance charge ( ). c. are always written first. Use to write the formula showing the ; however, are not written. No appear in the formula! For example, d. Criss-Cross Method The charge of the cation becomes the,, and the charge of the anion becomes the,. 3. Ternary Ionic Compounds a. Determine the. For example, b. Combine ions so that. All compounds are! For example, charges ( ) are needed to balance charge ( ). c. Write the first, and use to write the formula showing the. Parentheses are used when ; parentheses are placed around the with the subscript the closing parenthesis. For example, Bonding (Chapters 8, 9) Page 5
NAMING IONIC COMPOUNDS A. Binary Ionic Compounds 1. Name the using its. 2. Name the with the ending. 3. Name the following binary ionic compounds. NaBr KI MgCl 2 AlBr 3 B. Ternary Ionic Compounds 1. Name the. a. Monatomic cations: use the. b. Polyatomic cations: use the. 2. Name the. a. Monatomic anions: use the. b. Polyatomic anions: use the. 3. Name the following ternary ionic compounds. NH 4 Cl KClO MgSO 4 AlPO 3 C. Metal ions with 1. Determine the needed to form a. 2. Use a following the metal name to show the. 3. Examples a. CuCl total negative charge is in this compound, copper ion must have a therefore, compound name is b. CuCl 2 total negative charge is in this case, copper ion must have a therefore, compound name is Bonding (Chapters 8, 9) Page 6
c. The Roman numeral is the, not the involved. d. Roman numerals most often used: e. Exceptions: 1 2 3 4 5 f. Name the following compounds using the Stock System. SnCl 2 PbSO 4 SnCl 4 Pb(SO 4 ) 2! Practice: For each of the following pairs of elements: 1. Draw the Lewis dot diagram for each element in the pair. 2. Diagram the transfer of electron(s) from metal to nonmetal as ions are formed. 3. Write the correct formula for the resulting neutral ionic compound. EXAMPLE: magnesium and oxygen 1. lithium and chlorine 2. aluminum and phosphorus Bonding (Chapters 8, 9) Page 7
PROPERTIES OF IONIC COMPOUNDS A. Positive and negative ions, forming a three-dimensional arrangement of ions called a. B. A is referred to as a but does not actually exist. C. Ionic bonds are due to the. The strong force of attraction gives these compounds and. D. Ionic compounds are and are described as. E. The formation of ionic bonds is, meaning it. F. Ionic compounds are conductors of electricity when ( ) or (dissolved in ) but not in the. : compound whose aqueous solution conducts electricity HYDROGEN AS A CATION A. Compounds in which hydrogen is the cation (H + ) are formed through the ( ) but are treated like for the purposes of naming and writing formulas. B. The naming of binary compounds containing hydrogen as the cation depends on the. 1. When the physical state is ( ), ( ), or ( ), the compound is named like all other binary ionic compounds. For example, HCl (g) is named. 2. When the hydrogen-containing compound is in, the binary compound is named as a. For example, HCl (aq) is named. C. The naming of (polyatomic ion contains ) does not depend on the physical state. Follow naming rules for tertiary acids. Bonding (Chapters 8, 9) Page 8
D. Flowchart for Naming Acids ACIDS Binary Acids (two elements) Tertiary Acids (three elements) o o FORMATION OF COVALENT MOLECULES A. Covalent molecules are formed by the. The two atoms share an to attain a stable. B. Lewis illustrate the that are available for sharing as well as the that are not. Example: Water consists of two hydrogen atoms and one oxygen atom. Draw Lewis dot structures for these atoms. H O H Hydrogen has valence electron(s) and needs more to become stable, with a configuration like. Oxygen has valence electron(s) and needs more to attain a configuration like. Each atom contributes to the covalent bond, resulting in (circled). In Lewis, replace the shared pairs of electrons and represent. Bonding (Chapters 8, 9) Page 9
For each of the following pairs of elements: 1. Draw the Lewis dot structure for each element in the pair. 2. Circle the lone electrons that can be shared covalent bonds. 3. It may be necessary to add more than one atom of the involved elements in order for both elements to become stable 4. Write the correct formula for the resulting covalent molecule. EXAMPLE: carbon and chlorine 1. nitrogen and hydrogen 2. hydrogen and chlorine 3. oxygen and oxygen Bonding (Chapters 8, 9) Page 10
PROPERTIES OF COVALENT COMPOUNDS A. Individual particles of covalent compounds are referred to as. B. Covalent bonds between atoms in molecules are and result from forces of attraction. C. forces (AKA ) are forces of attraction separate molecules and are than the. Examples: D. The of covalent bonds is related to. The the bond length, the the bond. Type of Bond # e Shared Bond Length Bond Strength Single Double Triple E. Many covalent compounds exist as or that at room temperature. F. Most covalent molecules in the solid state are. These molecular solids have., such as quartz or diamond, are more similar to ionic compounds. G. Molecules in the solid state form a similar to ionic solids, but there is. H. Covalent molecules are, meaning they. Bonding (Chapters 8, 9) Page 11
ELECTRONEGATIVITY! Practice: A. Definition: B. When moving across the period (L to R), electronegativity ; within a group (bottom to top), electronegativity. C. The difference in electronegativity values for two atoms can be used to. 1. EN differences usually indicate. Na (EN = ) and Cl (EN = ); EN difference = 2. EN differences usually form. H (EN = ) and O (EN = ); EN difference = C (EN = ) and O (EN = ); EN difference = 3. EN differences are considered to be. F (EN = ) and F (EN = ); EN difference = N (EN = ) and O (EN = ); EN difference = Predict the bond type based on electronegativity differences. calcium and chlorine: ionic polar covalent nonpolar covalent hydrogen and nitrogen: ionic polar covalent nonpolar covalent lithium and bromine: ionic polar covalent nonpolar covalent iodine and iodine: ionic polar covalent nonpolar covalent POLARITY OF COVALENT BONDS A. Covalent can be described as, based on EN differences. B. Differences in electronegativity can result in in a covalent bond. The electronegative element has a attraction for electrons and leads to a molecule with areas ( ) of, indicated by and. Such molecules are called. Bonding (Chapters 8, 9) Page 12
C. The is characteristic of a covalent bond, which occurs between atoms with. POLARITY OF COVALENT MOLECULES A. Covalent molecules can also be described as. 1. Some nonpolar molecules contain nonpolar bonds. are always formed with nonpolar covalent bonds. The EN difference between two atoms of the same element is always equal to. Such molecules are in shape. 2. molecules may contain bonds, but due to their, the partial charges are. consists of atom bonded to atoms. Each bond is (EN difference = ) with exerting a stronger attraction for electrons. The molecule, however, is due to its symmetrical shape ( ). 3. Polar molecules contain bonds and are in shape. Because the molecule has definite areas of, it is a, also called a. is a polar molecule, with exerting a stronger due to its. Therefore, the partial negative charge is found on, and the partial positive charge is found on. Bonding (Chapters 8, 9) Page 13
The shape of a water molecule is described as. The between the on the central oxygen atom bends the molecule. B. The of molecules helps determine the of these compounds. 1. Solubility: Solubility is determined by and. The basic rule determining solubility is described as. dissolve in. molecules will only dissolve in. NAMING COVALENT COMPOUNDS A. Binary Covalent Compounds 1. Name first element in the formula by simply using. 2. The suffix is added to the root of the. 3. are used to indicate the number of atoms of each element as shown by the. # of Atoms Prefix # of Atoms Prefix 1 6 2 7 3 8 4 9 5 10 Exceptions: B. Common Names of Molecular Compounds Formula Common Name Molecular Compound Name H 2 O NH 3 Bonding (Chapters 8, 9) Page 14