Drill How do chemists model the valence electrons in metal atoms?

Objective SWBAT: Explore molecular compounds in order to describe the information provided by a molecular formula.

SAT/HSA Enrichment Atoms of elements in a group on the periodic Table have similar… This similarity is most closely related to the atoms’… Physical properties … number of principal energy levels. Physical properties … atomic masses. Chemical properties … atomic numbers. Chemical properties … number of valence electrons. Chemical properties … number of orbitals.

Inquiry Activity 20 min Shapes of Molecules Purpose Students learn about geometric shapes that characterize molecules. 20 min

What information does a molecular formula provide? Molecular Compounds What information does a molecular formula provide?

Molecular Compounds These toy models are made from circular pieces joined together in units by sticks. Atoms can also be arranged in different ways to make a variety of products.

Molecules and Molecular Compounds In nature, matter takes many forms. The noble gases, including helium and neon, are monatomic. That means they exist as single atoms. The noble gases, including helium and neon, are monatomic. That means they exist as single atoms. Helium, being less dense than air, is often used to inflate balloons. The colors produced in what we commonly call neon lights are a result of passing an electric current through one or more noble gases.

Molecules and Molecular Compounds Some compounds are so different from ionic compounds that attractions between ions fail to explain their bonding. The atoms held together by sharing electrons are joined by a covalent bond.

Molecules and Molecular Compounds A molecule is a neutral group of atoms joined together by covalent bonds. Air contains oxygen molecules. A diatomic molecule is a molecule consisting of two atoms. An oxygen molecule is a diatomic molecule.

Molecules and Molecular Compounds A compound composed of molecules is called a molecular compound. Water and carbon monoxide are molecular compounds. Water is a molecular compound with molecules composed of two hydrogen atoms and one oxygen atom. Carbon monoxide is a molecular compound with molecules composed of one carbon atom and one oxygen atom.

Molecules and Molecular Changes Molecular compounds tend to have relatively lower melting and boiling points than ionic compounds.

Molecules and Molecular Compounds Sodium chloride, which is an ionic compound, and water, which is a molecular compound, are compared here. Interpreting Diagrams How do molecular compounds differ from ionic compounds?

Molecules and Molecular Changes Ethane, a component of natural gas, is also a molecular compound. Ethane is a component of natural gas. Inferring What information about the ethane molecule given by its molecular formula C2H6 is also given by the drawing shown here?

Molecular Formulas A molecular formula is the chemical formula of a molecular compound. A molecular formula shows how many atoms of each element a molecule contains.

Molecular Formulas Ammonia (NH3) is used in solution as a cleaning agent. You can represent the ammonia molecule by its molecular formula, its structural formula, a space-filling molecular model, a perspective drawing, or by a ball-and stick molecular model.

Molecular Formulas Formulas of Some Molecular Compounds The formula of a molecular compound indicates the numbers and kinds of atoms. The arrangement of the atoms within a molecule is called its molecular structure. Using Models Which of these molecules has the greatest number of oxygen atoms?

Section Quiz Compared to ionic compounds, molecular compounds tend to have relatively low melting points and high boiling point. low melting points and low boiling points. high melting points and high boiling points. high melting points and low boiling points.

Section Quiz A molecular compound usually consists of two metal atoms and a nonmetal atom. two nonmetal atoms and a metal atom. two or more metal atoms. two or more nonmetal atoms.

Section Quiz A molecular formula shows how many atoms of each element a molecule contains. a molecule's structure. which atoms are bonded together. how atoms are arranged in space.

Teacher Demo Purpose Materials Students see the structure associated with molecular formulas. Materials Molecular Model Kit

Teacher Demo Procedure: Questions: Construct models of different pairs of molecules. Questions: How many of each type of atom is in each molecule. Write the corresponding chemical formulas on the board.

Teacher Demo Discuss: The recipe for a cake provides information about what type and how much of each ingredient is needed. Varying the types and amounts of ingredients leads to cakes that have different tastes and textures.

Teacher Demo Question: How does a molecular formula provide similar information about a compound? Answer: (The subscripts in a molecular formula tell the number of atoms of each element in a compound)

Teacher Demo Explanation: Subscripts are not always in the smallest whole-number ratio of the atoms. For example: Ethane is correctly represented by the formula C2H6 because the molecule actually contains two carbon atoms and six hydrogen atoms. It would be incorrect to represent ethane as CH3.

Teacher Demo Question: How many atoms of nitrogen are in N2H4? How many atoms of hydrogen? 4

Review Look at the following formulas: Br2, KBr, CH4, SO3, N2H2, Ne2 Questions: Identify any substance that does not exist. Ne2 Identify any Ionic compounds. KBr Which formulas represent molecules? Br2, CH4, SO3, N2H2

Review Look at the following formulas: Br2, KBr, CH4, SO3, N2H2, Ne2 Questions: Which formulas represent compounds? Br2, CH4, SO3, N2H2 How many atoms are in SO3? 4

Summary Did we accomplish our objective? Explain. What information does a molecular formula provide? Describe how the molecule whose formula is NO is different from the molecule whose formula is N2O. What information does a molecule’s molecular structure give?

Exit Ticket Molecular Compounds Homework: NO HOMEWORK ()