Bonding Construction Activity

Ionic Bonding

Atoms can achieve a noble gas electron configuration by losing or gaining electrons to form ions. Metals lose electrons to form positive ions and non-metals gain electrons to form negative ions.

Sodium can attain the stable electron configuration of neon by losing one electron

Na (1s22s22p63s1)Na+ (1s22s22p6 – Neon’s stable configuration) + 1e-

With ten electrons and eleven protons the ion formed has a positive charge (Na+1).

Fluorine is one electron short of the neon electron configuration. If it obtains one electron (from sodium) it can achieve a full outer shell of eight electrons.

F (1s22s22p5) + 1e-F- (1s22s22p6 – Neon’s stable configuration)

The species formed has ten electrons and nine protons; it is a negatively charged fluoride ion (F-1).

xx + xx -

Na·+ x · x

x F xNa x F x

xxxx

Properties of Ionic Compounds

1.Crystalline solids

2.High melting and boiling points

3.Soluble in water

4.Conduct electricity when molten or dissolved in water

Covalent Bonding

Covalent bonds are formed by the sharing of electrons between non-metal atoms. The two atoms have to approach sufficiently close to each other for their atomic orbitals to overlap.

Dot-and cross Diagrams

Dot-and cross diagrams are simplified versions of the diagram for the chlorine molecule on the left below, showing only the outer shell electrons


Multiple Covalent Bonds

Multiple covalent bonds may involve the sharing of two or even three pairs of electrons between atoms.

orNN

Properties of Covalent Compounds

1. Usually soft and brittle

2. Low melting and boiling points

3. Insoluble in water

4. Do not conduct electricity when solid or molten

Prelab Questions:

  1. Ionic bonds are formed between ______and ______.
  2. When an ionic bond forms, electrons are ______between atoms.
  3. Cations and anions try to gain or lose electrons to reach a ______electron arrangement in their valence shells just like ______gases.
  4. Covalent bonds are formed between ______and ______.
  5. When covalent bonds form, electrons are ______between atoms.

  6. How are ionic and covalent compounds different in their properties? (discuss 4)
  7. Complete the table:

Ionic Compound Construction

Instructions:

Read through the instructions before you begin…

  1. Using nonpermanent markers, color the valence electrons on each element card that you will be using to construct ionic formulas. Color metal valence electrons red. Color nonmetal valence electrons blue.
  1. On your desktop, construct ionic compounds using element cards. Remember, metals will lose electrons to nonmetals during a chemical reaction.
  1. Also remember that metals are trying to reach a stable octet by losing their valence shell, nonmetals want to gain enough electrons in their valence shell to reach a stable octet of electrons (like a noble gas). Your teacher will demonstrate how to build the model for magnesium + oxygen.

Example: Magnesium + oxygen

  1. Draw the formula structure on your answer sheet. Use arrows to show the electron transfer from the metal to the nonmetal.
  1. Write the resulting formula MgO
  1. Name the compound Magnesium oxide

Ionic Compound Construction Site

  1. Potassium + oxygen

Teacher initials for model ______

Ionic formula structure w/arrows:

Formula ______

Name ______

  1. Aluminum + chlorine

Teacher initials for model ______

Ionic formula structure w/arrows:

Formula ______

Name ______

  1. Magnesium + sulfur

Teacher initials for model ______

Ionic formula structure w/arrows:

Formula ______

Name ______

  1. Sodium + phosphorus

Teacher initials for model ______

Ionic formula structure w/arrows:

Formula ______

Name ______

Build your own ionic compound (remember metal-nonmetal)

  1. ______+ ______

Teacher initials for model ______

Ionic formula structure w/arrows:

Formula ______

Name ______

Covalent Compound Construction

Instructions:

  1. Color the valence electrons on each card you will be using to construct your covalent compounds. Color the first atom in the covalent formula red; color the second atom blue.
  1. Construct the molecular compound pairing up valence electrons.
  1. Draw the formula structure on your answer sheet. Show the sharing of electrons and stable octets around atoms by drawing circles around the element s and their valence electrons.

  1. Your teacher will demonstrate how to build the molecular compound CH4

Example: CH4

Covalent Compound Construction Site

  1. NI3

Teacher initials for covalent model ______

Molecular structure w/ circles:

  1. SiO2

Teacher initials for covalent model ______

Molecular structure w/ circles:

  1. PCl3

Teacher initials for covalent model ______

Molecular structure w/ circles:

  1. CI4

Teacher initials for covalent model ______

Molecular structure w/ circles:

Build your own covalent compound

  1. (remember, nonmetal-nonmetal)

Teacher initials for covalent model ______

Molecular structure w/ circles:

Molecular Formula ______

Conclusion:

Discuss three differences between ionic compounds and covalent compounds.

One difference between ionic and covalent compounds is______