Chemical Bonding: Ionic and Covalent
Comparing how atoms bond and form compounds
Chemical Bonding: Ionic and Covalent
Comparing how atoms bond and form compounds
Chemistry - Grade 9-12
- 1
Explain how an ionic bond forms between atoms.
Think about electron transfer and opposite charges.
An ionic bond forms when one atom transfers one or more electrons to another atom. This creates a positively charged ion and a negatively charged ion, and the opposite charges attract each other. - 2
Explain how a covalent bond forms between atoms.
A covalent bond forms when atoms share one or more pairs of electrons. The shared electrons help each atom fill its outer energy level and become more stable. - 3
Classify the bond in sodium chloride, NaCl, as ionic or covalent and explain your choice.
Look at the types of elements involved.
The bond in sodium chloride is ionic because sodium is a metal and chlorine is a nonmetal. Sodium transfers an electron to chlorine, forming ions that attract each other. - 4
Classify the bond in water, H2O, as ionic or covalent and explain your choice.
The bonds in water are covalent because hydrogen and oxygen are both nonmetals. They share electrons rather than transfer them. - 5
Magnesium reacts with oxygen to form magnesium oxide, MgO. Describe what happens to the electrons during bond formation.
Magnesium is in Group 2 and oxygen is in Group 16.
Magnesium loses two electrons and becomes a 2+ ion. Oxygen gains those two electrons and becomes a 2- ion, so an ionic bond forms between them. - 6
Why do ionic compounds usually have high melting points?
Ionic compounds usually have high melting points because the electrostatic attractions between the positive and negative ions are strong. A large amount of energy is needed to separate the ions. - 7
Why do many covalent compounds have lower melting and boiling points than ionic compounds?
Compare attractions between molecules with attractions between ions.
Many covalent compounds have lower melting and boiling points because the forces between separate molecules are often weaker than the strong attractions in an ionic crystal lattice. Less energy is needed to separate the particles. - 8
A compound conducts electricity when dissolved in water but not as a solid. Is it more likely ionic or covalent? Explain.
It is more likely ionic because ionic compounds can conduct electricity when dissolved in water since their ions are free to move. In the solid state, the ions are fixed in place and cannot carry charge easily. - 9
Carbon dioxide, CO2, is made of carbon and oxygen. Is this compound ionic or covalent? Explain how you know.
Use the rule about metals and nonmetals.
Carbon dioxide is covalent because carbon and oxygen are both nonmetals. Nonmetals usually bond by sharing electrons. - 10
Compare the structure of an ionic compound with the structure of a molecular covalent compound.
An ionic compound is usually made of a repeating crystal lattice of positive and negative ions. A molecular covalent compound is made of separate molecules in which atoms are joined by shared electrons. - 11
Predict whether potassium bromide, KBr, is likely to be brittle or flexible as a solid. Explain your answer.
Think about what happens when an ionic crystal is struck.
Potassium bromide is likely to be brittle as a solid because it is an ionic compound. When layers of ions shift, ions with the same charge can line up and repel each other, causing the crystal to crack. - 12
Write one major difference and one similarity between ionic and covalent bonding.
One major difference is that ionic bonding involves electron transfer, while covalent bonding involves electron sharing. One similarity is that both types of bonding help atoms become more stable by filling their outer energy levels.