PHYSICAL SCIENCE

Name: Date: Student Exploration: Polarity and Intermolecular Forces Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: dipole, dipole-dipole force, dipole-induced dipole force, electronegativity, intermolecular force, ionic bond, London dispersion force, molecule, nonpolar, nonpolar covalent bond, partial charges, polar, polar covalent bond, valence electron Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. A big bully is having a tug-of-war with a small child. There is a ball attached to the middle of the rope. Toward whom will the ball move? The Child because of gravity so the ball will go down instead of up looking at the picture. 2. Two equally strong kids are having a tug-of-war. What do you expect to happen to the ball in this situation? Well because the rope wont go up or down depending on who is stronger. The rope will be straight and the ball will not move at all. Gizmo Warm-up Just like in a tug-of-war, atoms that are bonded to one another pull on the electrons they share. In the Polarity and Intermolecular Forces Gizmo, you will explore how these opposing forces relate to bond types and the forces between molecules. To begin, drag the O (oxygen) and H (hydrogen) atoms into the simulation area forming H2O. Turn on Show valence electrons. A valence electron is found in the outermost energy level of the atom. 1. Click Play ( ). What do you notice? The valence electrons from the Hydrogen mix up with the valence electrons of the Oxygen. 2. Which atom seems to be pulling more on the hydrogen's one valence electron? How do you know? The bottom electrons on the oxygen are the ones pulling on the hydrogen one electrons. 3. What happens to the colors of the simulated atoms, and what does this indicate? Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved Originally they are purple but when the atoms are being mixed together they turn into a reddish on top and a blue color on the bottom. The hydrogen is blue and the Oxygen is reddish. Activity A: Bond polarity Get the Gizmo ready: ● On the BOND POLARITY tab, click Reset ( ). ● Drag the atoms out of the simulation area. Introduction: A neutral atom has the same number of protons as electrons. Atoms that gain electrons become negatively charged, while those that lose electrons become positive. A polar bond forms when shared electrons are pulled closer to one atom than another, causing the bonded atoms to become partially charged. In a nonpolar bond, electrons are shared equally. Question: What causes bonds to be polar or nonpolar? 1. Observe: Select the Show polar molecule insert checkbox. The animation shows the probable location of electrons (orange dots) in a polar molecule. A. What do you notice about the distribution of the electrons? I see that on one side ( left ) most of the orange dots ( electrons ) are there. They seem to stick together. On the right side there are a small amount of electrons because most of them are on the left side. B. How does this electron distribution affect the charges of the bonded atoms? Well the distribution is clearly one sided. Because this is a polar bond you can clearly see all the electrons are pulled to one atom. Now the electron distribution can affect the charge of the bond because we know that when an atom gains electrons they are negative and when they lose they are positive. If the molecule is polar there's gonna be one atom where it's fully negative and one that is fully positive due to when it's a polar molecule the electrons all go to one side. If the molecule is nonpolar both atoms will either be half negative and positive and equal due to the fact they share the same amount of electrons. 2. Observe: Turn on the Show nonpolar molecule inset. A. How are the electrons in this molecule distributed? In this way, because nonpolar molecules share equal amounts of electrons throughout both atoms, all the electrons are equally separated throughout both of the atoms. B. Why do the bonded atoms remain neutral? Because they aren't losing or gaining. They are at a neutral amount of electrons and neither one has more or Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved less because they both share the same amount. 3. Experiment: Turn off Show polar molecule inset and Show nonpolar molecule inset. Check that Show valence electrons are turned on. Drag the O and H atoms into the simulation area. Click Play. Note the colors. Red indicates a negative charge, while blue indicates a positive charge. A. Does an ionic, polar or nonpolar bond form? Polar. From looking at the diagram you can see there are more electrons on top then there are on the bottom. What I mean is that there are more electrons leading to one atom then there are to the other one. Which means this is a polar bond because when it's polar it means electrons are leading towards one side than the other. Ionic bonds are bonds that form between metal and nonmetal atoms. In this bond, valence electrons are transferred from a metal to a nonmetal. Drag each of these metal/nonmetal combinations into the Ionic bond bin on the upper right. 4. Experiment: Now try forming bonds between different combinations of nonmetal