What happens at the molecular level when a compound dissolves in water? This interactive animation explores how negative and positive ions in sodium chloride (table salt) collide with water molecules and become separated from each other to become a solution. The model does an effective job of depicting how the water molecules disrupt the attraction between the positive sodium ions and the negative chloride ions, and then become stabilized by attractions to the atoms in the water molecule.
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Editor's Note: This animation could be very helpful in building a foundation to understand covalent and ionic bonding. It is paced so that students ranging from grades 6-12 can comprehend what is happening, especially if they refer to the glossary for unfamiliar words. Be sure not to miss the additional materials in this large collection. Author Mark Bishop also created two textbooks in introductory chemistry (available in free digital format), Power Point presentations for teachers, tutorials, student guides, and more.
Metadata instance created
May 2, 2011
by Caroline Hall
September 25, 2014
by Caroline Hall
AAAS Benchmark Alignments (2008 Version)
4. The Physical Setting
4D. The Structure of Matter
6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
6-8: 4D/M1b. The atoms of any element are like other atoms of the same element, but are different from the atoms of other elements.
6-8: 4D/M1cd. Atoms may link together in well-defined molecules, or may be packed together in crystal patterns. Different arrangements of atoms into groups compose all substances and determine the characteristic properties of substances.
6-8: 4D/M3cd. In solids, the atoms or molecules are closely locked in position and can only vibrate. In liquids, they have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions.
6-8: 4D/M8. Most substances can exist as a solid, liquid, or gas depending on temperature.
9-12: 4D/H2. The number of protons in the nucleus determines what an atom's electron configuration can be and so defines the element. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons.
9-12: 4D/H7a. Atoms often join with one another in various combinations in distinct molecules or in repeating three-dimensional crystal patterns.
9-12: 4D/H8. The configuration of atoms in a molecule determines the molecule's properties. Shapes are particularly important in how large molecules interact with others.
9-12: 4D/H10. The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them.
11. Common Themes
6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.
6-8: 11D/M3. Natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.
Next Generation Science Standards
Matter and Its Interactions (MS-PS1)
Students who demonstrate understanding can: (6-8)
Develop models to describe the atomic composition of simple molecules and extended structures. (MS-PS1-1)
Disciplinary Core Ideas (K-12)
Structure and Properties of Matter (PS1.A)
Gases and liquids are made of molecules or inert atoms that are moving about relative to each other. (6-8)
In a liquid, the molecules are constantly in contact with others; in a gas, they are widely spaced except when they happen to collide. In a solid, atoms are closely spaced and may vibrate in position but do not change relative locations. (6-8)
The changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter. (6-8)
Each atom has a charged substructure consisting of a nucleus, which is made of protons and neutrons, surrounded by electrons. (9-12)
The structure and interactions of matter at the bulk scale are determined by electrical forces within and between atoms. (9-12)
A stable molecule has less energy than the same set of atoms separated; one must provide at least this energy in order to take the molecule apart. (9-12)
Chemical Reactions (PS1.B)
Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants. (6-8)
Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy. (9-12)
Crosscutting Concepts (K-12)
Cause and Effect (K-12)
Cause and effect relationships may be used to predict phenomena in natural systems. (6-8)
Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system. (9-12)
Structure and Function (K-12)
Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts, therefore complex natural structures/systems can be analyzed to determine how they function. (6-8)
The functions and properties of natural and designed objects and systems can be inferred from their overall structure, the way their components are shaped and used, and the molecular substructures of its various materials. (9-12)
NGSS Science and Engineering Practices (K-12)
Developing and Using Models (K-12)
Modeling in 6–8 builds on K–5 and progresses to developing, using and revising models to describe, test, and predict more abstract phenomena and design systems. (6-8)
Develop and use a model to describe phenomena. (6-8)
Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. (9-12)
Use a model to provide mechanistic accounts of phenomena. (9-12)
%0 Electronic Source %A Bishop, Mark %D 2011 %T An Introduction to Chemistry: Dissolving Sodium Chloride %V 2014 %N 18 December 2014 %9 application/flash %U http://preparatorychemistry.com/NaCl_flash.htm
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