Bonding All chemical bonds are formed as a result of the simultaneous attraction of two or more electrons. All chemical bonds are formed as a result of the simultaneous attraction of two or more electrons. Each atom is trying to achieve the electron configuration of a noble gas Each atom is trying to achieve the electron configuration of a noble gas (creating filled s and p orbitals which results in a symmetrical arrangement of electrons that cause a stable compound) (creating filled s and p orbitals which results in a symmetrical arrangement of electrons that cause a stable compound)

Valence Electrons Electrons are divided between core and valence electrons. Na 1s 2 2s 2 2p 6 3s 1 Core = [Ne] and valence = 3s 1 Br [Ar] 3d 10 4s 2 4p 5 Core = [Ar] 3d 10 and valence = 4s 2 4p 5

Valence Electrons 1A 2A3A4A5A6A7A 8A Number of valence electrons is equal to Group number.

The degree of attraction is based on the difference in their electronegativity values or electron attracting power of the atoms. The degree of attraction is based on the difference in their electronegativity values or electron attracting power of the atoms. There are three general classifications of chemical bonds that can be formed. There are three general classifications of chemical bonds that can be formed.

Bonding Three types of bonds Three types of bonds 1.Ionic: a bond formed due to the 1.Ionic: a bond formed due to the electrostatic attraction between a positive and negative ion caused electrostatic attraction between a positive and negative ion caused by an exchange of electrons. 2.Covalent:a bond formed between two 2.Covalent:a bond formed between two non-metals due to a sharing of electrons. non-metals due to a sharing of electrons. 3. Metallic :a bond between metal ions 3. Metallic :a bond between metal ions formed due to a “sea of electrons”.

Ionic Bonds These bonds are formed when the electronegativity differences between the two atoms are large (>2.1 or = 2.1) These bonds are formed when the electronegativity differences between the two atoms are large (>2.1 or = 2.1) In the tug of war for the electrons, this means that one atom is capable of pulling the electron completely out of the other atom’s energy level and into its own creating positively and negatively charged ions. In the tug of war for the electrons, this means that one atom is capable of pulling the electron completely out of the other atom’s energy level and into its own creating positively and negatively charged ions.

Ionic Bonding Ionic bonding: results from the electrostatic attraction between cations and anions. Ionic bonding: results from the electrostatic attraction between cations and anions. Formation of an ionic bond can be viewed as a transfer of electrons. Formation of an ionic bond can be viewed as a transfer of electrons.

This causes the formation of a positive ion, cation, and a negative ion, anion. This causes the formation of a positive ion, cation, and a negative ion, anion. This causes an electrostatic attraction between the positive and negative ion This causes an electrostatic attraction between the positive and negative ion The ionic compound is then composed of alternating positive and negative ions arranged in a crystal lattice structure. The ionic compound is then composed of alternating positive and negative ions arranged in a crystal lattice structure.

The metals would release electrons and become positively charged. The elements which would release the electrons would be from Groups 1 (alkali metals) and Group 2 (alkaline earth metals) along with some of the heavier metals in Groups 13, 14, and 15 and the transition elements. The metals would release electrons and become positively charged. The elements which would release the electrons would be from Groups 1 (alkali metals) and Group 2 (alkaline earth metals) along with some of the heavier metals in Groups 13, 14, and 15 and the transition elements.

The non-metals would accept electrons and become negatively charged. These elements would be found in the Group 16 ( the oxygen family) and Groups 17 ( the halogens) The non-metals would accept electrons and become negatively charged. These elements would be found in the Group 16 ( the oxygen family) and Groups 17 ( the halogens)

Properties of Ionic Solids Crystalline solids at room temperature Crystalline solids at room temperature Have higher melting and boiling points as compared to covalent compounds Have higher melting and boiling points as compared to covalent compounds Most are soluble in water but not soluble in non-polar solvents. Most are soluble in water but not soluble in non-polar solvents. Conduct electrical current in molten or solution state Conduct electrical current in molten or solution state Are extremely polar bonds. Are extremely polar bonds.

Naming and Formulas When naming the ionic solid the metals name always comes first When naming the ionic solid the metals name always comes first The non-metal comes last but the ending of the non-metal name is dropped and changed to ide. The non-metal comes last but the ending of the non-metal name is dropped and changed to ide. Examples: Examples: NaCl = sodium chloride NaCl = sodium chloride H 2 S = hydrogen sulfide H 2 S = hydrogen sulfide Li 2 O = lithium oxide Li 2 O = lithium oxide

Ionic solids using transition elements: Ionic solids using transition elements: Again start with the metal, but include in parenthesis with Roman numerals the size of the charge, copper(II) or iron (III). Again start with the metal, but include in parenthesis with Roman numerals the size of the charge, copper(II) or iron (III). Then end with the non-metals ide ending. Then end with the non-metals ide ending. Examples: Examples: FeCl 3 is iron (III) chloride FeCl 3 is iron (III) chloride SnI 4 is tin (IV) iodide SnI 4 is tin (IV) iodide CuO is copper (II) oxide CuO is copper (II) oxide

Polyatomic ions: Polyatomic ions: The only positive polyatomic ion is ammonium. This would begin the name and the end would follow the rules previously stated for ionic compounds. The only positive polyatomic ion is ammonium. This would begin the name and the end would follow the rules previously stated for ionic compounds. The negative polyatomic ions each have a specific name and so the metal would follow the previous rules followed by the name of the polyatomic ion. The negative polyatomic ions each have a specific name and so the metal would follow the previous rules followed by the name of the polyatomic ion.

Polyatomic Ions The following list are some of the most common polyatomic ions that would be good to memorize. The following list are some of the most common polyatomic ions that would be good to memorize. NH 4 + ammonium (the only positive ion) Anions:(negative 1 ions) NO 3 - nitrate NO 2 - nitrite OH - hydroxide CN - cyanide C 2 H 3 O 2 - acetate MnO 4 - permanganate

Anions (negative 2 and negative 3 ions) Anions (negative 2 and negative 3 ions) SO 4 2- sulfate SO 4 2- sulfate SO 3 2- sulfite SO 3 2- sulfite CrO 4 2- chromate CrO 4 2- chromate Cr 2 O 7 2- dichromate Cr 2 O 7 2- dichromate CO 3 2- carbonate CO 3 2- carbonate PO 4 3- phosphate PO 4 3- phosphate

Formulas Each formula must end up being electrically neutral. Each formula must end up being electrically neutral. After identifying the charge on each of the positive and negative ions, use subscripts to denote how many of each ion must be used to make the compound electrically neutral. After identifying the charge on each of the positive and negative ions, use subscripts to denote how many of each ion must be used to make the compound electrically neutral. Examples Examples Lithium is 1+ and oxygen is 2- thus you would need two lithiums with one oxygen Li 2 O Lithium is 1+ and oxygen is 2- thus you would need two lithiums with one oxygen Li 2 O Calcium is 2+ and chlorine is 1- thus you need two chlorines for the one calcium, CaCl 2 Calcium is 2+ and chlorine is 1- thus you need two chlorines for the one calcium, CaCl 2 Iron can be 3+ and fluorine is 1- thus FeF 3 Iron can be 3+ and fluorine is 1- thus FeF 3 Iron can also be 2+ and fluorine 1-, thus FeF 2 Iron can also be 2+ and fluorine 1-, thus FeF 2

For compounds with polyatomic ions. For compounds with polyatomic ions. Ammonium chloride it would be NH 4 Cl since NH 4 is 1+ and Cl is 1- Ammonium chloride it would be NH 4 Cl since NH 4 is 1+ and Cl is 1- Calcium carbonate is CaCO 3 since Ca is 2+ and CO 3 is 2- Calcium carbonate is CaCO 3 since Ca is 2+ and CO 3 is 2- Magnesium phosphate is Mg 3 (PO 4 ) 2 Magnesium phosphate is Mg 3 (PO 4 ) 2

Examples: Examples: Sn(OH) 2 tin (II) hydroxide Sn(OH) 2 tin (II) hydroxide Pb(C 2 H 3 O 2 ) 4 lead (IV) acetate Pb(C 2 H 3 O 2 ) 4 lead (IV) acetate NH 4 NO 3 ammonium nitrate NH 4 NO 3 ammonium nitrate CoSO 3 cobalt (II) sulfite CoSO 3 cobalt (II) sulfite Fe 2 (CO 3 ) 3 iron (III) carbonate Fe 2 (CO 3 ) 3 iron (III) carbonate Ni 3 (PO 4 ) 2 nickel (II) phosphate Ni 3 (PO 4 ) 2 nickel (II) phosphate

Covalent bonds Polar covalent bonds are formed when the electronegativity differences between the two atoms are greater or equal to 0.4 and less than 2.1 Polar covalent bonds are formed when the electronegativity differences between the two atoms are greater or equal to 0.4 and less than 2.1 In the tug of war for the electrons, this means that neither atom is able to completely pull the electron from the other atoms energy levels resulting in an unequal sharing of electrons. In the tug of war for the electrons, this means that neither atom is able to completely pull the electron from the other atoms energy levels resulting in an unequal sharing of electrons.

Non-polar covalent bonds are formed when the electronegativity differences between the two atoms are less than 0.4 Non-polar covalent bonds are formed when the electronegativity differences between the two atoms are less than 0.4 In the tug of war for the electrons, this means that both atoms have virtually the same strength of attraction for the electrons resulting in the electrons being located halfway between both nuclei. In the tug of war for the electrons, this means that both atoms have virtually the same strength of attraction for the electrons resulting in the electrons being located halfway between both nuclei.

In covalent bonded molecules, the charges on the ions are determined by which atom has the greatest electronegativity value. That atom would take it’s normal oxidation state or charge, forcing the other atom to take a more unnatural charge. In covalent bonded molecules, the charges on the ions are determined by which atom has the greatest electronegativity value. That atom would take it’s normal oxidation state or charge, forcing the other atom to take a more unnatural charge.

Examples: Examples: CO 2 for carbon dioxide, the oxygen is more electronegative resulting in the oxygen taking its normal 2- charge. This forces the carbon to take a 4+ charge. CO 2 for carbon dioxide, the oxygen is more electronegative resulting in the oxygen taking its normal 2- charge. This forces the carbon to take a 4+ charge. COfor carbon monoxide the oxygen will still take the 2- charge but that forces the carbon to become a 2+ charge. COfor carbon monoxide the oxygen will still take the 2- charge but that forces the carbon to become a 2+ charge. P 2 S 5 Sulfur is more electronegative thus it will take a 2- charge resulting in a total of 10 negative charges. This makes each phosphorus a 5+ charge to create a neutral compound. P 2 S 5 Sulfur is more electronegative thus it will take a 2- charge resulting in a total of 10 negative charges. This makes each phosphorus a 5+ charge to create a neutral compound.

Naming Covalent Compounds When forming covalent compounds with two non-metal the use of prefixes is needed. When forming covalent compounds with two non-metal the use of prefixes is needed. 1 mono6hexa 1 mono6hexa 2di7hepta 2di7hepta 3tri8 octa 3tri8 octa 4tetra9 nona 4tetra9 nona 5penta10 deca 5penta10 deca

Examples: Examples: COcarbon monoxide COcarbon monoxide CO 2 carbon dioxide CO 2 carbon dioxide P 2 S 5 diphosphorus pentasulfide P 2 S 5 diphosphorus pentasulfide N 2 O 4 dinitrogen tetraoxide N 2 O 4 dinitrogen tetraoxide