Kinetic Molecular Theory of Matter PDF

Lesson 1.1 Kinetic Molecular Theory of Matter General Chemistry 2 Science, Technology, Engineering, and Mathematics Have you ever bought an ice cream on a hot summer day? 2 If yes, then you must have noticed how ice cream, when taken out of the free...

Lesson 1.1 Kinetic Molecular Theory of Matter General Chemistry 2 Science, Technology, Engineering, and Mathematics Have you ever bought an ice cream on a hot summer day? 2 If yes, then you must have noticed how ice cream, when taken out of the freezer, takes a definite shape, but when exposed in the summer heat, slowly loses its form and melts. 3  In this lesson, you will be learning about theories governing the different states of matter. You will learn the relationship of the different macroscopic properties of matter to that of its molecular interactions. 4 What does the kinetic molecular theory state? 5 Learning Competency At the end of the lesson, you should be able to do the following: Use the kinetic molecular model to explain properties of liquids and solids (STEM_GC11IMF-IIIa-c-99). 6  Learning Objectives At the end of the lesson, you should be able to do the following: Explain the kinetic molecular theory of matter. Compare and contrast the different states of matter based on the kinetic molecular theory. 7  Kinetic Molecular Theory of Matter The kinetic molecular theory of matter provides an overview of the microscopic properties of molecules or atoms and their interactions. It describes the microscopic properties of matter and how they translate to the state and other properties of matter. 8  Kinetic Molecular Theory of Matter It states that 1. Matter is composed of small particles. 2. The molecules interact with one another through attractive forces. The strength of these forces is related to the distance between the particles. 9  Kinetic Molecular Theory of Matter It states that 3. These molecules are always in constant random motion. 4. The temperature of a substance is a measure of the average kinetic energy of the molecules. 10  Kinetic Molecular Theory of Matter Matter Is Composed of Small Particles Earlier atomic models 11  Kinetic Molecular Theory of Matter Matter Is Composed of Small Particles Atoms are the building blocks of matter. gold bar gold atoms 12  Kinetic Molecular Theory of Matter Matter Is Composed of Small Particles Matter can also exist as molecules. drop of water water molecules 13  Kinetic Molecular Theory of Matter Matter Is Composed of Small Particles Matter can also exist as molecules. table salt sodium and chloride ions 14  Kinetic Molecular Theory of Matter Molecules Interact through Attractive Forces The attractive forces between molecules are known as the intermolecular forces. The stronger the interaction between two molecules, the smaller their distance will be. 15  Kinetic Molecular Theory of Matter Molecules Interact through Attractive Forces solid liquid gas 16 Solids Solids have particles with strong intermolecular forces such that their particles are very close to one another. particles of solid 17  Liquids Liquids have intermediate intermolecular forces. This makes liquid particles farther from one another compared to those in solids. particles of liquid 18 Gases Gases have particles that are very far apart from one another due to weak intermolecular forces. particles of gas 19  Kinetic Molecular Theory of Matter Molecules Are in Constant Random Motion All molecules are in constant random motion. The extent of their motion varies depending on the temperature and strength of the interaction between the particles. 20  Kinetic Molecular Theory of Matter Nanoscale Representation of Matter molecules in ice molecules in molecules in 21 water steam Solids Solids, due to their strong intermolecular forces, have restricted motion. The particles of solids are only able to vibrate back and forth around a specific point or location. particles of solid 22  Liquids Liquids, having intermediate intermolecular forces, are able to move past each other. Since their particles are still close to one another, the motion is restricted to small distances as particles of liquid they will collide with 23 Gases Gases, having weak intermolecular forces, are able to move in relatively long distances before colliding with another molecule. This happens because the particles are very far apart from one another. particles of gas 24  Kinetic Molecular Theory of Matter Temperature Is a Measure of the Average KE heat increases KE increases 25  States of Matter Matter can be described in terms of its physical state. It can either be solid, liquid, or gas. solid liquid gas (ice) (water) (steam) 26  States of Matter State of Compressibili Shape Volume Matter ty solid fixed shape fixed volume virtually incompressible liquid depends on fixed volume only slightly compressible the container gas depends on assumes the volume very compressible the container of the container 27  States of Matter Particulate Drawings of Solid, Liquid, and Gas 28 How can the kinetic molecular theory explain the properties of each state of matter? 29 Based on the kinetic molecular theory of matter, the state of a matter is determined by two factors— temperature and strength of intermolecular forces.  Properties of the States of Matter As explained by KMT: At lower temperatures, intermolecular forces determine the state of a substance. Substances with intermediate to strong intermolecular forces will form a condensed phase, either solid or liquid. Those with weak intermolecular forces will be in the gaseous state. 31 How does the kinetic molecular theory explain phase changes? 32  Phase Changes Recall that a higher temperature means a higher average kinetic energy. This means that the particles will have enough energy to move around faster. Increasing the temperature also weakens the intermolecular forces of attraction. 33 Melting The molecules in ice vibrates back and forth to a specific location since it is in the solid phase. Increasing the temperature will provide enough kinetic energy to overcome their strong intermolecular forces. The solid becomes a liquid in a process called 34 Vaporization When liquid water is heated, its particles are able to move past one another in relatively longer distances. The process in which liquid is converted to a gas is called vaporization. 35 Did You Know? Ice-skating is possible since the molecules in ice are farther apart than they are in liquid water. 36  How does the kinetic molecular theory describe phases and phase changes? 37  Check Your Understanding Identify the state of matter being described below. 1. The particles vibrate at a specific location only. 2. The particles move about in relatively short distances. 3. The particles move in longer distances. 38  Let’s Sum It Up! The kinetic molecular theory states that: ○ Matter is composed of small particles. ○ The molecules interact with one another through attractive forces. The strength of these forces is related to the distance between the particles. ○ These molecules are always in constant random motion. ○ The temperature of a substance is a measure of the average kinetic energy of the molecules. 39  Let’s Sum It Up! Solids have particles with strong intermolecular forces that cause the particles to be close together. This causes the particles’ motion to be restricted to vibrations. 40  Let’s Sum It Up! Liquids have particles with intermediate intermolecular forces that cause the particles to be farther apart from each other than in solids. This allows the particles to move about but in relatively short distances. 41  Let’s Sum It Up! Gases have particles with negligible intermolecular forces that cause the particles to be very far apart from one another. Due to the large distances between particles, the molecules are able to move in long distances. 42  Let’s Sum It Up! The average kinetic energy of the molecules can be measured by determining the temperature. 43  Let’s Sum It Up! The physical state of matter is affected by both kinetic energy and intermolecular forces. ○ At low temperatures, intermolecular forces dominate. ○ At high temperatures, the molecules have higher kinetic energy and will be able to overcome the intermolecular forces present. 44 Challenge Yourself Describe the phase changes using the kinetic molecular theory. Evaluate whether the changes require an increase or decrease in temperature. 45 Bibliography Brown T.L. et al. Chemistry: The Central Science. Pearson Prentice -Hall, 2005. Boundless. “Kinetic Molecular Theory and Gas Laws.” Boundless Chemistry. Accessed August 12, 2016. https://www.boundless.com/chemistry/textbooks/boundless-chemistry- textbook/gases-5/kinetic-molecular-the Chang, Raymond, and Kenneth A. Goldsby. General Chemistry: the Essential Concepts. New York: McGraw-Hill, 2014. Petrucci, Ralph H. General Chemistry: Principles and Modern Applications. Toronto, Ont.: Pearson Canada, 2011. Print. Silberberg, Martin S. Principles of General Chemistry. New York: McGraw-Hill, 2013. 46