Covalent Bonding

Covalent Bonds A bond between two(2) or more NON-METAL atoms A bond between two(2) or more NON-METAL atoms Only have to worry about the small amount of non- metals on the right side of the staircase (no others) Only have to worry about the small amount of non- metals on the right side of the staircase (no others) *Hydrogen is the only exception. Treat hydrogen as a non-metal* *Hydrogen is the only exception. Treat hydrogen as a non-metal* Electrons between the atoms are SHARED to form the bond Electrons between the atoms are SHARED to form the bond No electrons are lost or gained, therefore no ions are formed No electrons are lost or gained, therefore no ions are formed This means you do NOT have to worry about charges at all! This means you do NOT have to worry about charges at all! Unfortunately however, naming and formulas for covalent bonds is a completely different process Unfortunately however, naming and formulas for covalent bonds is a completely different process

Naming and Formulas for Covalent Bonds Instead of using ions and charges to determine the names and numbers of atoms in formulas, when we are dealing covalent compounds we use prefixes  Instead of using ions and charges to determine the names and numbers of atoms in formulas, when we are dealing covalent compounds we use prefixes  Prefixes indicate the number of atoms in a covalent compound AND they are used in naming covalent compounds Prefixes indicate the number of atoms in a covalent compound AND they are used in naming covalent compounds Prefixes: Prefixes: 1 – “mono” 1 – “mono” 2 – “di” 2 – “di” 3 – “tri” 3 – “tri” 4 – “tetra” 4 – “tetra” 5 – “penta” 5 – “penta” 6 – “hexa” 6 – “hexa” 7 – “hept” 7 – “hept” 8 – “oct” 8 – “oct” 9 – “non” 9 – “non” 10 - “deca” 10 - “deca”

Naming when given the formula Step 1: Begin by writing down the names of the elements involved in the correct order Step 1: Begin by writing down the names of the elements involved in the correct order i.e.: P 2 O 5 i.e.: P 2 O 5 = phosphorus oxygen = phosphorus oxygen Step 2: Based on the number of each of the atoms involved, add in the correct prefix to the element names Step 2: Based on the number of each of the atoms involved, add in the correct prefix to the element names i.e.: P 2 O 5 i.e.: P 2 O 5 = diphosphorus pentoxygen = diphosphorus pentoxygen Step 3: Change the ending of the last element to the suffix “ide” Step 3: Change the ending of the last element to the suffix “ide” i.e.: P 2 O 5 i.e.: P 2 O 5 = diphosphorus pentoxide = diphosphorus pentoxide

Getting the formula when given the name Step 1: Find the symbol of the atoms involved on the periodic table Step 1: Find the symbol of the atoms involved on the periodic table i.e.: dinitrogen tribromide = i.e.: dinitrogen tribromide = N & Br N & Br Step 2: Write the symbols down beside each other in the correct order Step 2: Write the symbols down beside each other in the correct order i.e.: dinitrogen tribromide = i.e.: dinitrogen tribromide = NBr NBr Step 3: Determine the number of each element is needed from the prefixes and place the number as a subscript on the right side of the symbol Step 3: Determine the number of each element is needed from the prefixes and place the number as a subscript on the right side of the symbol i.e.: dinitrogen tribromide = i.e.: dinitrogen tribromide = N 2 Br 3 N 2 Br 3

Tricky Rules The prefix “mono” is only used on the element that is named second The prefix “mono” is only used on the element that is named second i.e.: CO i.e.: CO Name = carbon monoxide Name = carbon monoxide Not monocarbon monoxide Not monocarbon monoxide Do not reduce any of the subscripts in covalent formulas Do not reduce any of the subscripts in covalent formulas i.e.: C 2 H 4 stays as C 2 H 4, not CH 2 i.e.: C 2 H 4 stays as C 2 H 4, not CH 2 Compounds that only have one particular element in them do not need to include the (1) subscript in the formula Compounds that only have one particular element in them do not need to include the (1) subscript in the formula i.e.: Nitrogen monosulfide i.e.: Nitrogen monosulfide Formula = NS Formula = NS Not N 1 S 1 Not N 1 S 1

Examples Give formulas for the following: Give formulas for the following: Carbon dioxide Carbon dioxide CO 2 CO 2 Trintrogen hexabromide Trintrogen hexabromide N 3 Br 6 N 3 Br 6 Diboron heptachloride Diboron heptachloride B 2 Cl 7 B 2 Cl 7 Give names for the following: Give names for the following: N 3 I 5 N 3 I 5 Trinitrogen pentaiodide Trinitrogen pentaiodide SiF 4 SiF 4 Silicon tetrafluoride Silicon tetrafluoride SeCl SeCl Selenium monochloride Selenium monochloride