Molecules in Motion

Learning Resource Type

Classroom Resource

Subject Area

Science

Grade(s)

8

Overview

In this lesson, students add food coloring to hot and cold water to see whether heating or cooling affects the speed of water molecules. Students watch molecular model animations to see the effect of heating and cooling on the molecules of a liquid. Students will also draw their own molecular model.

Science (2015) Grade(s): 8

SC15.8.1

Analyze patterns within the periodic table to construct models (e.g., molecular-level models, including drawings; computer representations) that illustrate the structure, composition, and characteristics of atoms and molecules.

UP:SC15.8.1

Vocabulary

  • Element
  • Atom
  • Protons
  • Nucleus
  • Electrons
  • Neutrons
  • Atomic number
  • Periodic table
  • Array
  • Atomic mass
  • Period
  • Group
  • Chemical properties
  • Physical properties
  • Molecule
  • Bond
  • Chemical bond
  • Valence electron
  • Ion
  • Ionic bond
  • Nonmetal
  • Metal
  • Covalent bond
  • Metallic bond
  • Conductivity

Knowledge

Students know:
  • Elements are substances composed of only one type of atom each having an identical number of protons in each nucleus.
  • Atoms are the basic units of matter and the defining structure of elements.
  • Atoms are made up of three particles: protons, neutrons and electrons.
  • The number of protons in an atom's nucleus is equal to the atomic number.
  • The periodic table arranges all the known elements in an informative array.
  • Elements are arranged left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass.
  • Rows in the periodic table are called periods. As one moves from left to right in a given period, the chemical properties of the elements slowly change.
  • Columns in the periodic table are called groups. Elements in a given group in the periodic table share many similar chemical and physical properties.
  • The period number of an element signifies the highest energy level an electron in that element occupies (in the unexcited state). The number of electrons in a period increases as one traverses down the periodic table; therefore, as the energy level of the atom increases, the number of energy sub-levels per energy level increases.
  • A molecule is formed when two or more atoms bond together chemically.
  • A chemical bond is the result of different behaviors of the outermost or valence electrons of atoms.
  • Ionic bonds are the result of an attraction between ions that have opposite charges. Ionic bonds usually form between metals and nonmetals; elements that participate in ionic bonds are often from opposite ends of the periodic table. One example of a molecule that contains an ionic bond is table salt, NaCl.
  • Covalent bonds form when electrons are shared between atoms rather than transferred from one atom to another. The two bonds in a molecule of carbon dioxide, CO2, are covalent bonds.
  • Metallic bonds exist only in metals, such as aluminum, gold, copper, and iron. In metals, each atom is bonded to several other metal atoms, and their electrons are free to move throughout the metal structure. This special situation is responsible for the unique properties of metals, such as their high conductivity.

Skills

Students are able to:
  • Analyze patterns within the periodic table to construct models of atomic and molecular structure, composition, and characteristics.
  • Identify the relevant components of the atomic and molecular models.
  • Describe relationships between components of the atomic and molecular models.

Understanding

Students understand that:
  • Patterns in the periodic table predict characteristic properties of elements. These trends exist because of the similar atomic structure of the elements within their respective group families or periods, and because of the periodic nature of the elements.
  • The structure, composition, and characteristics of atoms and molecules are dependent upon their position in the periodic table.

Scientific and Engineering Practices

Developing and Using Models

Crosscutting Concepts

Patterns
Science (2015) Grade(s): 8

SC15.8.4

Design and conduct an experiment to determine changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.

UP:SC15.8.4

Vocabulary

  • Particle motion
  • Temperature
  • State [of Matter]
  • Pure substance
  • Thermal Energy
  • Kinetic Energy
  • System

Knowledge

Students know:
  • Changes in particle motion of a pure substance occur when thermal energy is added to or removed from a system.
  • Changes in temperature of a pure substance occur when thermal energy is added to or removed from a system.
  • Changes in state of a pure substance occur when thermal energy is added to or removed from a system.

Skills

Students are able to:
  • Identify the phenomena under investigation, which includes changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.
  • Identify the purpose of the investigation, which includes determining changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.
  • Develop a plan for the investigation individually or collaboratively.
  • Describe factors used in the investigation including appropriate units (if necessary), independent and dependent variables, controls and number of trials for each experimental condition.
  • Perform the investigation as prescribed by the plan.
  • Use data from the investigation to provide an causal account of the relationship between the addition of removal of thermal energy from a substance and the change in the average kinetic energy of the particles in a substance.

Understanding

Students understand that:
  • Adding or removing thermal energy from a system causes changes in particle motion of a pure substance.
  • Adding or removing thermal energy from a system causes changes in temperature of a pure substance.
  • Adding or removing thermal energy from a system causes changes in state of a pure substance.

Scientific and Engineering Practices

Planning and Carrying out Investigations

Crosscutting Concepts

Systems and System Models

CR Resource Type

Lesson/Unit Plan

Resource Provider

American Chemical Society

License Type

Custom

Accessibility

Video resources: includes closed captioning or subtitles
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