Name Date Class

Model and Invent Modeling Chemical Bonding

Lab Preview

Directions: Answer these questions before you begin the Lab.

  1. Why should you wear goggles during this experiment?
    Protective eyewear should be worn to prevent potential injury to the eyes from loose beans in this Lab.

  2. What is the difference between an ionic bond and a covalent bond?
    In an ionic bond, an element (generally a metal) loses electrons to a nonmetal element in order to form a stable compound. In a covalent bond, electrons are shared
    (generally between two nonmetals).

Chemical bonding is one of the most important concepts in chemistry. Bonding is what makes different compounds. Even though atoms have nuclei containing protons and neutrons, the part of the atom that is most important to chemists is outside the nucleus.

Real-World Problem

How are electrons involved in chemical bonding?

Goals

Possible Materials

modified egg carton
beans
*pennies
*buttons
*Alternate materials

Safety Precautions

Complete a safety worksheet before you begin.

Make a Model

  1. Obtain a modified egg carton and beans from your teacher. The egg carton represents the first and second energy levels of an atom. The beans represent electrons.
  2. Decide which elements you can model by the number of beans you have. Consider how the periodic table can be used to determine the number of outer electrons in an element.
  3. Model all the elements that you can create using the modified egg carton and beans.
  4. Draw the models of elements that you created on a separate piece of paper.
  5. Determine if the elements form ionic or covalent bonding. Record your conclusions on a separate piece of paper.

Test Your Model

  1. Look for element combinations that could represent chemical formulas for compounds and molecules. Some formulas may require more than one atom to form some types of elements and compounds.
  2. Work with other students to make models of compounds and molecules produced by chemical bonding.
  3. Draw the models of the compounds and molecules you made on your separate piece of paper. Record the type of bonding used to make the compounds and molecules.

Analyze Your Data

  1. Explain how you can use the periodic table to identify the element that represents your model.
    The periodic table provides the atomic number of each element. This number represents the number of protons in the nucleus of an atom of the element. Since atoms are neutral, they have as many electrons as protons. Consequently, the atomic number also reflects the number of electrons in an atom of an element. By counting the number of beans (electrons), the student can identify the element.
  2. Explain whether elements in the metal groups on the periodic table have more or fewer electrons in their outer energy levels than the nonmetals.
    Metals have fewer electrons in their outer energy levels than nonmetals, making them unstable and more likely to lose electrons and bond in order to fill their outer energy levels. Metals and nonmetals generally form ionic bonds.
  3. The combinations of elements could represent chemical formulas. Explain why some formulas require more than one atom of an element.
    In a stable compound, the outer energy level of each element must be filled. In some compounds, it is necessary to include more than one atom of an element to satisfy this requirement. For example, a molecule of the compound water (H2O) must contain 2 atoms of hydrogen (each with 1 electon) and 1 atom of oxygen (with 8 electrons). In this way, the outer energy level - energy level 2- is filled (2 electrons fill energy level 1 and 8 electrons fill energy level 2).

Conclude and Apply

  1. Describe why your model could be used to show examples of both ionic and covalent bonding.
    The model included energy levels 1 and 2. Since there are 2 electrons in level 1 and 8 electrons in level 2, the elements are those whose atomic numbers span 1 to 10: Hydrogen (H), Helium (He), Lithium (Li), Beryllium (Be), Boron (B), Carbon (C), Nitrogen (N), Oxygen (O), Flourine (F), and Neon (Ne). Lithium and beryllium are metals that can form ionic bonds with nonmetals. Noble gases (Helium and Neon) are stable because their outer electron shells are filled; they do not form bonds easily.
    Nonmetals ( the remaining elements in the group) form covalent bonds with other nonmetals.
  2. Predict what element your model would be if you receive ten beans. Explain your reasoning.
    The first energy level can hold 2 electrons; the second level can hold 8 electrons. Since the unknown elements has 10 electrons, it is the noble gas Neon, with an atomic number of 10.

Communicating Your Data

Compare your conclusions with other students' conclusions. What elements did their models represent? Explain how their elements differed in ability to form ionic and covalent bonds.