AP Chemistry Unit 6

Big Idea:

The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangements of atoms. These atoms retain their identity in chemical reactions.

Chemical and physical properties of materials can be explained by the structure and the arrangement of atoms, ions, or molecules and the forces between them.

Student Expectations:

Focus Standards

Enduring understanding 1.B: The atoms of each element have unique structures arising from interactions between electrons and nuclei.

Essential knowledge

• 1.B.1: The atom is composed of negatively charged electrons, which can leave the atom, and a positively charged nucleus that is made of protons and neutrons. The attraction of the electrons to the nucleus is the basis of the structure of the atom. Coulomb’s law is qualitatively useful for understanding the structure of the atom.
• 1.B.2: The electronic structure of the atom can be described using an electron configuration that reflects the concept of electrons in quantized energy levels or shells; the energetics of the electrons in the atom can be understood by consideration of Coulomb’s law.

Enduring understanding 1.C: Elements display periodicity in their properties when the elements are organized according to increasing atomic number. This periodicity can be explained by the regular variations that occur in the electronic structures of atoms. Periodicity is a useful principle for understanding properties and predicting trends in properties. Its modern-day uses range from examining the composition of materials to generating ideas for designing new materials.

Essential knowledge

• 1.C.1: Many properties of atoms exhibit periodic trends that are reflective of the periodicity of electronic structure.
• 1.C.2: The currently accepted best model of the atom is based on the quantum mechanical model.

Enduring understanding 1.D: Atoms are so small that they are difficult to study directly; atomic models are constructed to explain experimental data on collections of atoms

Essential knowledge

• 1.D.1: As is the case with all scientific models, any model of the atom is subject to refinement and change in response to new experimental results. In that sense, an atomic model is not regarded as an exact description of the atom, but rather a theoretical construct that fits a set of experimental data.
• 1.D.3: The interaction of electromagnetic waves or light with matter is a powerful means to probe the structure of atoms and molecules, and to measure their concentration.

Enduring understanding 2.B: Forces of attraction between particles (including the noble gases and also different parts of some large molecules) are important in determining many macroscopic properties of a substance, including how the observable physical state changes with temperature.

Essential knowledge

• 2.B.2: Dipole forces result from the attraction among the positive ends and negative ends of polar molecules. Hydrogen bonding is a strong type of dipole-dipole force that exists when very electronegative atoms (N, O, and F) are involved.
• 2.B.3: Intermolecular forces play a key role in determining the properties of substances, including biological structures and interactions

Enduring understanding 2.C: The strong electrostatic forces of attraction holding atoms together in a unit are called chemical bonds.

Essential knowledge

• 2.C.1: In covalent bonding, electrons are shared between the nuclei of two atoms to form a molecule or polyatomic ion. Electronegativity differences between the two atoms account for the distribution of the shared electrons and the polarity of the bond.
• 2.C.2: Ionic bonding results from the net attraction between oppositely charged ions, closely packed together in a crystal lattice.
• 2.C.3: Metallic bonding describes an array of positively charged metal cores surrounded by a sea of mobile valence electrons.
• 2.C.4: The localized electron bonding model describes and predicts molecular geometry using Lewis diagrams and the VSEPR model.

Enduring understanding 2.D: The type of bonding in the solid state can be deduced from the properties of the solid state.

Essential knowledge

• 2.D.1: Ionic solids have high melting points, are brittle, and conduct electricity only when molten or in solution.
• 2.D.2: Metallic solids are good conductors of heat and electricity, have a wide range of melting points, and are shiny, malleable, ductile, and readily alloyed
• 2.D.3: Covalent network solids generally have extremely high melting points, are hard, and are thermal insulators. Some conduct electricity.
• 2.D.4: Molecular solids with low molecular weight usually have low melting points and are not expected to conduct electricity as solids, in solution, or when molten.

Enduring understanding 5.C: Breaking bonds requires energy, and making bonds releases energy.

Essential knowledge

• 5.C.2: The net energy change during a reaction is the sum of the energy required to break the bonds in the reactant molecules and the energy released in forming the bonds of the product molecules. The net change in energy may be positive for endothermic reactions where energy is required, or negative for exothermic reactions where energy is released.

Ongoing Standards

Science Practice 1 The student can use representations and models to communicate scientific phenomena and solve scientific problems.

Science Practice 2 The student can use mathematics appropriately.

Science Practice 3 The student can engage in scientific questioning to extend thinking or to guide investigations within the context of the AP course.

Science Practice 4 The student can plan and implement data collection strategies in relation to a particular scientific question. (Note: Data can be collected from many different sources, e.g., investigations, scientific observations, the findings of others, historic reconstruction and/or archived data.)

Science Practice 5 The student can perform data analysis and evaluation of evidence.

Science Practice 6 The student can work with scientific explanations and theories.

Science Practice 7 The student is able to connect and relate knowledge across various scales, concepts and representations in and across domains.

Student Learning Targets:

• Apply Coulomb’s Law qualitatively (including using representations) to describe the interactions of ions, and the attractions between ions and solvents to explain the factors that contribute to the solubility of ionic compounds. [LO 2.14, SP 1.4, SP 6.4]
• Create visual representations of ionic substances that connect the microscopic structure to macroscopic properties, and/ or use representations to connect the microscopic structure to macroscopic properties (e.g., boiling point, solubility, hardness, brittleness, low volatility, lack of malleability, ductility, or conductivity). [LO 2.19, SP 1.1, SP 1.4, SP 7.1, connects to 2.D.1, 2.D.2]
• Create a representation of an ionic solid that shows essential characteristics of the structure and interactions present in the substance. [LO 2.23, SP 1.1]
• Explain a representation that connects properties of an ionic solid to its structural attributes and to the interactions present at the atomic level. [LO 2.24, SP 1.1, SP 6.2, SP 7.1]
• Explain how a bonding model involving delocalized electrons is consistent with macroscopic properties of metals (e.g., conductivity, malleability, ductility, and low volatility) and the shell model of the atom. [LO 2.20, SP 6.2, SP 7.1, connects to 2.D.2]
• Use the electron sea model of metallic bonding to predict or make claims about the macroscopic properties of metals or alloys. [LO 2.26, SP 6.4, SP 7.1]
• Create a representation of a metallic solid that shows essential characteristics of the structure and interactions present in the substance. [LO 2.27, SP 1.1]
• Explain a representation that connects properties of a metallic solid to its structural attributes and to the interactions present at the atomic level. [LO 2.28, SP 1.1, SP 6.2, SP 7.1]
• Create or use graphical representations in order to connect the dependence of potential energy to the distance between atoms and factors, such as bond order (for covalent interactions) and polarity (for intermolecular interactions), which influence the interaction strength. [LO 5.1, SP 1.1, SP 1.4, SP 7.2, connects to Big Idea 2]
• Explain the properties (phase, vapor pressure, viscosity, etc.) of small and large molecular compounds in terms of the strengths and types of intermolecular forces. [LO 2.16, SP 6.2]
• Predict the type of bonding present between two atoms in a binary compound based on position in the periodic table and the electronegativity of the elements. [LO 2.17, SP 6.4]
• Rank and justify the ranking of bond polarity on the basis of the locations of the bonded atoms in the periodic table. [LO 2.18, SP 6.1] Use Lewis diagrams and VSEPR to predict the geometry of molecules, identify hybridization, and make predictions about polarity. [LO 2.21, SP 1.4]
• Create a representation of a covalent solid that shows essential characteristics of the structure and interactions present in the substance. [LO 2.29, SP 1.1]
• Explain a representation that connects properties of a covalent solid to its structural attributes and to the interactions present at the atomic level. [LO 2.30, SP 1.1, SP 6.2, SP 7.1]
• Create a representation of a molecular solid that shows essential characteristics of the structure and interactions present in the substance. [LO 2.31, SP 1.1]
• Explain a representation that connects properties of a molecular solid to its structural attributes and to the interactions present at the atomic level. [LO 2.32, SP 1.1, SP 6.2, SP 7.1]
• Design or evaluate a plan to collect and/or interpret data needed to deduce the type of bonding in a sample of a solid. [LO 2.22, SP 4.2, SP 6.4]
• Draw qualitative and quantitative connections between the reaction enthalpy and the energies involved in the breaking and formation of chemical bonds. [LO 5.8, SP 2.3, SP 7.1, SP 7.2]

Essential Questions:

• When tested in the laboratory, how can two hydrocarbons labeled C3 H6 O differ in properties?
• How can there be so many different kinds of things if there are only 92 naturally occurring elements?
• What makes carbon the perfect atom for the center of almost every organic molecule?
• What would life based on silicon be like?

Extra Information:

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