names and formulas of binary molecular compounds a binary molecular compound is a compound composed...
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Names and Formulas of Binary Molecular Compounds
• A binary molecular compound is a compound composed of atoms of two different elements, usually two non-metals, that are joined together with covalent bonds.
Rules for naming Binary Molecular compounds
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.2
1.) First Element in name and formula is usually the one farther to the left on the periodic table.
2.) Suffix “-ide” attached the name of the second element.
3.) Pre-fixes used to indicate how many atoms of each type are present in one molecule of the compound.
if first element is one (mono) don’t write it.
• What is the name of a binary molecular compound that contains one sulfur atom and six fluorine atoms?
Exceptions to the Rules
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.2
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• Compounds that contain hydrogen are exceptions to the general naming rules. Hydrogen is a non-metal, and hydrogen chloride (HCl) is molecular compound. Binary hydrogen compounds are named as though they are ionic compounds.
• Compounds that contain hydrogen and carbon are also named differently.
If hydrogen chloride was named according to the naming rules for molecular compounds, it would be called hydrogen monochloride.
HCl
Go over sample problem on P.g. 123 as a class.
Complete practice problems 9-10 on p.g. 123
IUPAC and Systematic Names
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.2
• The international system for naming chemicals is maintained by the International Union of Pure and Applied Chemistry (IUPAC).
• IUPAC has developed a systematic method for naming chemicals according to their composition.
These calcium sulfate crystals are found in Mexico. Thanks to IUPAC, scientists around the world can share information about them.
You and your group will read p.g. 124 – 125
Then you will read the article provided to you and complete the think about it 3-2F and briefly present to the rest of the class.
Think about it 3-2F
1 mark for
chemical formula
additional names
properties
interesting information
2 marks for
applications
Answer the three questions ( 1 mark each)
Info. presented neatly, correctly, creatively (1 mark)
Total ___ / 10
• Why is an international system for naming chemicals important?
An international system for naming chemicals ensures that scientists from all over the world can identify a chemical by its universal name and thus exchange information about their research and findings.
Key Naming Rules: A SummaryUNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.2
Section 3.2 Review
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.2
• Chemical compounds are named according to whether they are ionic or molecular.
• The formula of an ionic compound represents the ratio of the positive and negative ions in the electrically neutral compound.
• The formula of a molecular compound represents the number of atoms of each element in a molecule of the compound.
• Chemical names and formulas are standardized by bodies such as the International Union of Pure and Applied Chemistry (IUPAC).
3.3 Chemical Equations and the Law of Conservation of Mass
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
• Chemical reaction - when one or more substances (elements or compounds) change to form one or more different substances (elements or compounds).
• Reactants - the substances that undergo a chemical reaction
• Products - the substances formed in a chemical reaction
• What are some examples of chemical reactions that take place around you?
Word Equations
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
• The reactants are on the left side of the arrow, and the products are on the right side of the arrow.
The Conservation of Mass in Chemical Reactions
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
• You and your group will copy down the questions on the following slide.
• Next, you and your group will read p.g.130 – 132.
• Next you will find the answer to the question number that corresponds with your group number (ex. Group 1 answers question 1) on the next page.
• Your group will then present your answer to the rest of the class for their notes.
1.) Who is Antoine Lavoisier?
2.) What is the Law of Conservation of Mass?
3.) Explain the experiment performed to show the Law of Conservation of Mass.
4.) How does Dalton’s atomic theory relate to the Law of Conservation of Mass?
5.) What is a Chemical equation? What is the difference between a skeleton equation and a balanced equation?
6.) What is a Coefficient? What other information is sometimes shown in a chemical equation?
1.) French scientist from the late 1700s. Performed experiments to show the law of conservation of mass.
2.) In a chemical reaction, the total mass of the products is always the same as the total mass of the reactants.
3.) worked with mercury(II) oxide to make mercury and oxygen and measured the mass of the products and reactants and they were always the same.
4.) Atoms are not created or destroyed so every atom in the reactants are present in the products
Chemical Equations and the Law of Conservation of Mass
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
5.) Chemical equation - representation of a chemical reaction that uses chemical formulas and symbols.
• skeleton equation is incomplete.
• balanced chemical equation is complete because it takes the law of conservation of mass into consideration.
6.) A coefficient is a number placed in front of a chemical formula in a balanced equation to show how many atoms, molecules, or ions are involved in a reaction. Coefficients are used to balance a chemical equation.
Balancing Chemical Equations
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
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• When balancing chemical equations, write the skeleton equation and then use coefficients to balance the numbers of each kind of atom on each side of the yield arrow.
When do you change the subscripts to balance a chemical equation?
The skeleton chemical equation above becomes the balanced chemical equation below.
As your group read page 132.
Close your textbooks.
Elect one group member to be the “teacher”, and teach the rest of the group how to balance an equation using the following example
H2O2 (aq) ------ H2O (l) + O2 (g)
- Other group members ask question or correct when needed.
read “Tips for Writing and Balancing Chemical Equations” on p.g. 133.
In your notebook create an easy to read summary (in your own words, point form) of these tips. Be prepared to hand it in at the end of class.
Complete questions 13-18 on p.g. 133.
Correction –
18 f.) CaCl2(aq) + AgNO3(aq) AgCl(s) + Ca(NO3)2
Go over sample problem on P.g. 134 as a class.
Homework - today
Practice problems 11-13
Next class
P.g. 137
#6, 8, 13, 14, 16, 17, 18.
Tips for Writing and Balancing Chemical Equations
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
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• Balance equations by adjusting coefficients, never by changing chemical formulas.
• Balance metals first.
• Add coefficients to any elements last.
• Balance hydrogen and oxygen last. They often appear in more than one reactant or more than one product, so it is easier to balance them after the other elements are balanced.
• If a polyatomic ion appears in both a reactant and a product, treat it as a single unit.
Continued…
Tips for Writing and Balancing Chemical Equations
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
TO PREVIOUS SLIDE
• Once you think the chemical equation is balanced, do a final check by counting the atoms of each element one more time.
• If you go back and forth between two substances, using higher and higher coefficients, double-check each chemical formula. An error in a chemical formula might be preventing you from balancing the chemical equation.
• The following elements exist as diatomic molecules: hydrogen, H2(g); nitrogen, N2(g); oxygen, O2(g); fluorine, F2(g); chlorine, Cl2(g); bromine, Br2 (ℓ); and iodine, I2(s). Always write them as shown here in a chemical equation.
A diatomic molecule contains two atoms of the same element.
Section 3.3 Review
UNIT 2 Chapter 3: Chemical Names, Formulas, and Equations Section 3.3
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• In a chemical reaction, a reactant or reactants undergo a chemical change, forming a different substance or substances called products. Reactants and products may be elements or chemical compounds.
• According to the law of conservation of mass, the overall mass of the reactants is always equal to the overall mass of the products in a chemical reaction.
• Chemists use descriptions, word equations, and balanced chemical equations to represent chemical reactions.
• In a balanced chemical equation, there is always the same number of atoms of each element on each side of the equation, in accordance with the law of conservation of mass.