Lesson 23: Chapter 23 Covalent Bonding and Intermolecular Interactions

What are different types of intermolecular forces?

- dipole dipole interactions (middle) - hydrogen bonding (strongest) - dispersion forces (weakest)

Intermolecular Forces

- electromagnetic forces holding one molecule to another molecule - pretty weak

When do polyatomic ions form crystals? A. When they combine with metal atoms to form salts. B. When they combine with other non-metal atoms. C. never. D. A and B.

A and B - when they combine with metal atoms to form salts - when they combine with other non-metal atoms

Electronegativity

- a measure of how strongly atoms attract electrons - both ionization energy and electron affinity contribute to electronegativity - increases from left to right and increases from bottom to top

Molecular Ions

- groups of atoms covalently bound to each other that have a net charge because electrons have been lost or gained to facilitate formation of the covalent bonds - polyatomic ions - by adding or losing the extra electrons they form stable but charged compounds

Dipole

- the separation of positive and negative charge in a polar bond or molecule - dipole is stronger if the charges are separated more - a polar molecule can result if the dipoles of individual parts of the molecule add up to create a totally dipole for the entire molecule

Which of the following would best describe the characteristics of covalent materials? A. A brittle, transparent solid with a very high melting point. B. A shiny, malleable solid with a very high melting point. C. A non-conducting material with low melting and boiling points, likely liquid or gas at room temperature. D. A brittle, opaque solid with a very high melting point. E. A non-conducting solid at room temperature that will conduct if melted or dissolved.

a non-conducting material with low melting and boiling points, likely liquid or gas at room temperature

In carbon tetra-chloride, CCl44, what is true about the charge distribution? A. The carbon will be more negative than the chlorine. B. The chlorine will be more negative than the carbon. C. The chlorine and carbon would be equally negative. D. The atoms will become positive and negative ions. E. It is impossible to predict how the electrons will distribute themselves in this type of bond.

the chlorine will be more negative than the carbon

How would you describe the melting point of a substance formed by a substance containing molecular ions? A. extremely low B. low C. high

high

Which of the following is a true statement about melting and boiling points in materials made of covalent molecules? A. Molecules that contain double bonds melt and boil at higher temperatures because the bonds are stronger. B. Molecules that contain triple bonds are the most likely to be gases at room temperature. C. Molecules that are polar have lower melting and boiling points than non-polar molecules. D. Hydrogen bonding between molecules increases melting and boiling points. E. Van der Waals (dispersion) forces lower melting and boiling points.

hydrogen bonding between molecules increases melting and boiling points

Ammonium nitrate (NH4NO3), a common fertilizer, is an ionically bonded substance involving two polyatomic ions, ammonium (NH4+) and nitrate (NO3−). Ammonium nitrate dissolves well in a polar solvent such as water. Which of the following statements best describes what happens when this fertilizer dissolves in water? A. All of the bonds between atoms are broken allowing the individual atoms to float in the water. B. The compound breaks up into the two oppositely charged ions. The ions do not break apart. C. The compound breaks up completely and causes nitrogen gas, oxygen gas, and hydrogen gas to form. D. The compound doesn't break up at all. The entire compound floats in the water still bound together as ammonium nitrate.

the compound breaks up into the two oppositely charged ions, the ions do not break apart

What best describes how oxygen molecules would behave if mixed with water? A. They would dissolve well because they are polar. B. They would dissolve well because they are not polar. C. They would dissolve poorly or not at all because they are polar. D. They would dissolve poorly or not at all because they are not polar. E. They would dissolve well because they are ionic.

they would dissolve poorly or not at all because they are not polar

When are molecules conductors of electricity? A. When they combine with metal atoms to form salts. B. When they combine with other non-metal atoms. C. When they combine with metals and are then melted or dissolved D. Never.

when they combine with metals and are then melted or dissolved