Chemistry and the Environment 1
2
Review from Grade 10 Chemistry The Periodic Table some of these elements had similar behaviors 3
Review from Grade 10 Chemistry The Periodic Table some of these elements had similar behaviors 4
5
So what do the numbers mean? 6
What do you remember about electron shells? Structure: Stability: Atoms are most stable when they have full outer electron shells. Some elements gain or lose electrons to achieve this. Some elements will share electrons to achieve this. This is the basis of how elements can bond together. 7
Ionic Bonds Ionic Bonding ionic bonds occur when elements gain or lose electrons. They obtain charges in the process, then attract to elements of opposite charges ie sodium and chlorine ionic bonds form between metals and nonmetals 8
Ionic Bonding to name ionic compounds, simply write the name of the metal first, then the non metal with "ide" replacing the end of the nonmetal name. ex calcium and fluorine becomes: calcium fluoride 9
Ionic Bonding Sometimes groups of elements can behave as a single metal or non metal. These are called polyatomic ions. 10
Sometimes atoms of an element stick together. These are called polyatomic elements. Ionic Bonding 11
Writing Ionic Compound Chemical Formulas Ionic Bonding 1. Write the symbol and valence for the metal first, followed by the non metal. 2. Criss cross the valence numbers. Ignore the signs 3. Reduce (like fractions) if possible 12
Ex write the formula for the following: Ionic Bonding 1. sodium oxide 2. magnesium sulfide 3. ammonium bromide 4. aluminum sulfate 13
Watch out for multi valence metals Ionic Bonding when writing the names of compounds containing these, one must indicate which one is being referred to. (Backwards crisscross comes in handy here.) ex write the formula for iron III oxide ex write the name for Cu 2 SO 4 ex write the name for CrO 14
Molecular or Covalent Bonds Molecular Bonding molecular bonds are formed when nonmetals bond together. They don't take up or give away electrons... instead they share electrons to obtain full outer shells. 15
Molecular Bonding Writing Molecular Compound Chemical Names and formulas 1. Write the names of the symbols as they appear in the formula. 2. Prifixes indicate how many of each. 16
Examples: Molecular Bonding formula for sulfur dioxide Name of NI 3 17
Assignment Worksheet Naming Chemical Compounds Worksheet Writing Chemical Formulas 18
Balancing Equations Balancing Chemical Equations If you have ever had to stack firewood, you know there is significant mass there. What happens to the mass after the wood is burned? 19
Balancing Equations If one accounts for all of the stuff produced when wood is burned, they would find that the total mass before burning is exactly the same as the mass after. This is because of the Law of Conservation of Mass. It states... Matter cannot be created or destroyed in chemical and common physical changes. 20
In Chemistry we keep track of atoms before and after reactions in the chemical equations used to describe them. Coefficients in front of the compound formulas describe how many molecules are used in a reaction. Balancing Equations H 2 SO 4 + 2 NaOH Na 2 SO 4 + 2 H 2 O 21
Balancing Equations Balancing Equations Balancing equations involves placing coefficients in chemical equations to ensure that the law of conservation of mass is not violated by that equation. 22
Ricci's Rules for Balancing Equations Balancing Equations 1. Work your way from left to right, and balance all the non Hydrogen and Oxygen atoms. 2. Of the Hydrogens and Oxygens, balance the ones that occur least often next. 3. Usually, the most often occurring element takes care of itself. 4. Sometimes you need to apply the rules of lowest common multiples. 5. Sometimes you need to use the 0.5 rules. 23
Balancing Equation Examples Balancing Equations 1. C 5 H 12 + O 2 CO 2 + H 2 O 2. Ca(OH) 2 + H 3 PO 4 Ca 3 (PO 4 ) 2 + H 2 O 3. C 2 H 6 + O 2 CO 2 + H 2 O 4. S 8 + F 2 SF 6 24
Balancing Equation Assignment Balancing Equations Worksheet Balancing Equations 25
Attachments Naming Chemical Formulas Worksheet.docx Writing Chemical Names.docx Balancing Equations Worksheet.docx