Chemical Bonding Basics Quiz

Grade 8 · Science · Quiz

Test your understanding of ionic, covalent, and metallic bonds and the properties they create.

Questions

1. How many valence electrons does an oxygen atom have?

   1. 2
   2. 4
   3. 6
   4. 8
   Show answer

   Answer: 6

   Oxygen is in Group 16 of the periodic table, meaning it has 6 valence electrons in its outermost shell.

2. Which of the following is an example of a covalent compound?

   1. NaCl (table salt)
   2. MgO (magnesium oxide)
   3. H₂O (water)
   4. CaCl₂ (calcium chloride)
   Show answer

   Answer: H₂O (water)

   Water is formed by oxygen and hydrogen sharing electrons (covalent bonds). The others are ionic compounds.

3. An atom that loses 2 electrons becomes a:

   1. 2- ion (anion)
   2. 2+ ion (cation)
   3. Neutral atom
   4. Radioactive isotope
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   Answer: 2+ ion (cation)

   Losing electrons removes negative charge, leaving more protons than electrons — the result is a positively charged ion (cation).

4. Ionic compounds typically have high melting points because ionic bonds are strong.

   Show answer

   Answer: True

   Ionic compounds form strong crystal lattice structures held by electrostatic attraction, requiring a lot of energy to break apart.

5. What determines the type of bond formed between two atoms?

   1. The atomic mass of each atom
   2. The number of protons in the nucleus
   3. The difference in electronegativity between the atoms
   4. The temperature of the environment
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   Answer: The difference in electronegativity between the atoms

   Electronegativity difference determines bond type: large difference → ionic; small difference → covalent; near zero → nonpolar covalent.

6. In a metallic bond, valence electrons are:

   1. Transferred permanently to another atom
   2. Shared in a fixed location between two atoms
   3. Delocalized and free to move throughout the metal
   4. Held tightly by the nucleus
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   Answer: Delocalized and free to move throughout the metal

   In metallic bonding, valence electrons leave individual atoms and roam freely, creating a 'sea' that holds the metal ions together.

7. Most atoms bond in order to achieve ______ electrons in their outer shell, like a noble gas.

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   Answer: 8

   The octet rule states atoms are most stable with 8 electrons in their outer shell, matching the electron configuration of noble gases.

8. Which pair of elements is most likely to form an ionic bond?

   1. Carbon and hydrogen
   2. Oxygen and nitrogen
   3. Sodium and fluorine
   4. Carbon and oxygen
   Show answer

   Answer: Sodium and fluorine

   Sodium (a metal, low electronegativity) and fluorine (a nonmetal, high electronegativity) have a large electronegativity difference, favoring ionic bonding.

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