Virtual chemistry

Project title: Rutherford experiment This virtual laboratory is intended for use in chemistry classes on the following topics: Goals: Practical part Replicate Rutherford’s experiment to understand the structure of an atom. 2. On the screen, you can see a thin gold foil, an enlarged image of its atom as a “plum pudding” with electrons like “raisins”. In the top right corner of the screen is the “Legend” section, which shows the components of the atom. In the “Alpha particle” section, you can adjust the intensity of the alpha particle bombardment by moving the slider to the right or left. 3.Initiate alpha particle bombardment. Set the intensity to maximum. Enable the “Traces” option to track particle trajectories. Analyze the particle deflections. Repeat the bombardment with minimum intensity. Observe any particle scattering. What about the case when particle bombardment is at its lowest intensity? 4. Switch to the “Rutherford atom” mode, which represents the planetary model of an atom. In this model, the massive, positively charged nucleus is located at the center, surrounded by electron energy level orbitals. 5. The simulation allows observation of the experiment at both the multi-atom and nucleus levels. In the “Atom” section, you can modify the nuclear composition by adjusting the number of protons and neutrons. 6. Set the number of protons and neutrons to their minimum values. Bombard the atoms with alpha particles. 7. Repeat the previous step with the maximum number of protons and neutrons. 8. Questions: Conclusion In this activity, students explored the Thomson and Rutherford models of the atom, followed by a virtual experiment that simulated Rutherford’s experiment.

Project title:  Law of Conservation of Energy This virtual laboratory is intended for use in chemistry classes on the following topics: Goals: Practical part 2. The screen displays the tools you’ll need for the experiment: two racks with heaters and coolers, two cubes (iron and brick), and two beakers, one filled with water and the other with olive oil. In the top-left corner, you’ll find a moveable thermometer for measuring temperature. The top-right corner features the Energy symbols and Link heaters buttons. Enable Energy symbols to see the energy icons (E). Enable Link heaters to control both heaters simultaneously Before each experiment: After each experiment:  Virtual Experiment # 1 Place beakers of water and oil on the heating rack. Place a thermometer in each beaker. Slide the heater control to the “Heat” setting and hold. Once heated, move the heater control to the “Cool” setting.  Virtual Experiment #2 Place iron and brick blocks on a rack with heaters. Attach a thermometer to each block. Turn on the heaters by moving the slider to the “Heat” indicator and hold it there. Once heated, move the slider to the “Cool” indicator.  Virtual Experiment #3 Place the thermometer in each block. Heat the iron block for a few minutes. Then, place the hot iron on top of the brick to transfer heat to the brick.  Virtual Experiment # 4 Place a beaker filled with water and another filled with oil on the heating rack. Then, place a cube of iron in the water and a brick in the oil. Install a thermometer on each object (4 in total). Move the heater’s slider up to the Heat indicator and hold. Then move the slider to the Cool indicator. 3. At the end of the experiment, fill in the table below: Experiment No Describe or draw the observed changes Conclusion 1 2 3 4 4. Please answer the questions below: Conclusion The PhET simulation “Energy forms and changes” is an effective tool for studying the topics “Thermodynamics” and “Law of Conservation of Energy” in chemistry classes. It allows students to visually and interactively explore various examples of energy conversion, as well as independently formulate conclusions and use the knowledge gained to solve problems. The use of simulation contributes to the development of critical thinking, information processing skills, and interest in studying the subject.

The title of the Project: Electronegativity This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part This guide will walk you through using the PhET “Molecule Polarity” simulation to understand electronegativity in chemistry. 1.Launch the Simulation. Notice the three tabs: “Two Atoms”,  “Three Atoms” and “Real Molecules” (Java version required). We’ll focus on the “Two Atoms” model for now. 2.  Each atom has an “Electronegativity” slider. Checking the “Bond Dipole” box will show an arrow representing the bond polarity (dipole moment) if it exists. The size and direction of the arrow indicate the strength and direction of the polarity.Slide the “Electronegativity” bars back and forth to see how the electronegativity of each atom affects the molecule. 3.You can also choose to view “Partial Charges” and “Bond Character” by checking the boxes.  Partial charges show the slight positive or negative charge on each atom due to electronegativity differences. Bond character indicates the type of bond formed (ionic, covalent, etc.) based on electronegativity. 4. Explore by clicking the “Electron Density” button. This shows areas of high and low electron density.  Click “Electrostatic Potential” to see positive and negative charge regions within the molecule. 5. Click and drag the molecule to rotate it in any direction.  Then, click the “Electric Field” button. Observe how the molecule aligns itself with the electric field, with the positive end attracted to the negative side of the field and vice versa. 6. Discuss how changing the electronegativity of each atom affects the bond polarity (dipole moment) size and direction. 7.Now switch to the “Three Atoms” model. Here, you can adjust electronegativity, bond angles, and view both “Bond Dipoles” and the overall “Molecular Dipole”. Explain how the arrangement of atoms can influence the overall polarity of a molecule with more than two central atoms. Conclusion This virtual simulation provides a dynamic and interactive environment for students to explore the concept of electronegativity. By manipulating electronegativity and observing its impact on bond polarity, electron density, and interaction with electric fields, students can gain a deeper understanding of this fundamental chemical concept. The simulation offers various functionalities for both simple two-atom molecules and more complex three-atom structures, allowing for a gradual progression in learning.

The title of the Project: Study of the acidity and alkalinity of solution media This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part The “pH scale: Basics” simulation allows students to explore the pH of everyday liquids. They can determine if a solution is acidic or basic and learn how dilution with water affects pH. Step 1. Launch the simulation. You’ll see a beaker on the right where you can add solutions and a pH scale with a sensor on the left. Step 2. Use the dropdown menu at the top of the screen to pick a solution for testing. Step 3. Use the dropper to add some solution (like chicken soup) to the beaker. Then, drag the pH probe into the solution to see its pH level. You’ll discover that chicken soup is acidic. Step 4. See how adding water from the faucet changes the pH, but draining some solution doesn’t affect the pH. “Dilution is the process of making something less concentrated by adding more solvent, which is usually water.” Step 5. Compare how diluting acids and bases affects the solution’s pH. You might notice that the pH gets closer to 7 (neutral) in both cases. Virtual experiment Step 6. Select a substance from the list. Use the dropper to fill the beaker halfway (½ L). Step 7. Place the pH sensor in the beaker. Record the substance’s pH level and whether it’s acidic, basic, or neutral in a table below. Step 8. Fill the beaker completely (1 L) by clicking the water faucet. Now, record the substance’s pH level after dilution in the same table. Step 9. Repeat steps 6 through 8 for each substance listed in the table. Table 1 Substance pH level Acid/Base/Neutral pH level after dilution Battery acid 1.0 acidic 1.30 Blood Chicken soup Coffee Drain cleaner Hand soap Milk Orange juice Soda pop Spit Vomit Conclusion The “pH scale: Basics” simulation provides an interactive learning experience for students to grasp the concepts of pH, acidity, and basicity of common substances. By performing virtual experiments, students can observe how dilution with water affects the pH of both acidic and basic solutions.

The title of the Project: Electrolytic dissociation This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part This sim can be used to discover the key differences between acidic and basic solutions. Step 1. Run the simulation. There are two screens: “Intro” and “My Solution”. Let’s start with “Intro”. The “Intro” screen Here, you can explore properties of acids and bases, as well as the difference between strong and weak solutions. Step 2.  The screen shows a beaker with a solution. You can choose from a list of five solutions to investigate. Step 3. Let’s begin with a strong acid. There’s a magnified microscopic view of the solution. You can compare this view with a balanced chemical equation to identify the particles shown. The particles are colored to help you see their relative amounts.  Step 4. Now, generate a list of properties of acids and bases using the simulation tools. Let’s first take a look at the properties of a strong base. The pH of a solution can be determined with a pH meter or pH paper. Step 5. The conductivity of the solution can be tested with a meter. The amount of light produced by the light bulb helps you compare solution conductivity qualitatively. For example, you could compare the conductivity of this strong base with a weak base or water. Step 6. This screen can also help you understand how to use the terms “strong” and “weak” when describing acids or bases. Let’s start with a strong acid. You can use the graphical representation to see the amounts of undissociated acid, conjugate base, and hydronium ions in the solution. Step 7. Then, select a weak acid and note any changes in the equilibrium concentrations of the undissociated acid and conjugate base. Step 8. Once you have developed a definition of strong and weak acids, you can use the simulation to test and refine your definitions by comparing strong bases and weak bases. The “My solution” screen In this screen students can experiment with creating acid and base solutions to understand the difference between their strength and concentration. Step 9. This screen looks just like the first one and has all the same tools, but here’s the cool part: you can build your own solutions! This lets you play around with different starting concentrations and acid strengths to see how they affect the solution’s pH.   Step 10.You can use the My Solution screen to challenge yourself to see how many ways you can create a solution with a particular pH. For example, you might try to create solutions with a pH of 3. Let’s start by placing the pH meter in the solution and choosing the “Graph” view. Step 11. One way to create a solution with a pH of 3 is to set the strength toggle to “strong” and the initial concentration to 0.001 Molar. You should notice that the acid has completely dissociated and that the concentration of hydronium is 0.001 Molar. Step 12. To create a weak acid solution with a pH of 3.0, you could increase the initial concentration to 1.0 Molar and move the strength toggle to weak. You could then use the slider to adjust the pH to 3. Notice that although the acid does not completely dissociate, the concentration of hydronium ions is again approximately 0.001 Molar. You could explore additional ways to create solutions with a pH of 3, by varying the initial solution concentration as well as the acid strength. This exercise challenges the misconception that pH can be used to measure the strength of an acid or a base. It reinforces the idea that pH is a measure of hydronium ion concentration. This challenge also provides an opportunity to learn the appropriate use of the words “dilute” and “concentrated” when referring to acid-base solutions. Conclusion This simulation provides a virtual laboratory environment for students to investigate the fundamental concepts of acids and bases. Through interactive exploration, students can discover the unique properties of strong and weak solutions, understand how pH relates to hydronium ion concentration, and differentiate between concentration and strength. By addressing common misconceptions and allowing for experimentation, the simulation fosters a deeper understanding of these essential chemical principles.

The title of the Project: Balancing chemical equations This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part This simulation is your one-stop shop for learning how to balance chemical equations. Let’s begin by exploring the concept on the “Introduction” screen. The Introduction Screen 3. When you create a balanced equation, a happy face emoji appears to indicate you were successful. This happens for each equation you can choose from the bottom of the screen. 4. This screen also has some cool visual aids, like charts and scales, to help you picture what “balanced” really means.  5. Once you’ve played around, take a look at your balanced equations. See how many atoms of each element are on both sides – this will solidify the concept of balance for you. 6. You can also hide the molecules in the boxes by clicking a button at the top. The Game Screen 7. Once you are ready to test your balancing skills, head over to the Game screen. Here, you get to practice on three levels, each getting trickier than the last. 8. You can add a time limit for a challenge and mute the sound effects if you prefer. 9. At each level, you will be given five random equations to balance. The levels get progressively harder, so it’s recommended to start at Level 1 and work your way up. In Level 1, each equation only requires three coefficients to be balanced. The higher levels get more complex, with equations having two products and two reactants. 10. You receive 2 points if you answer correctly on the first try. 11. If you made a mistake, you can get a hint by clicking “Show why” before trying again.  12. A second correct attempt earns you a point.   13. The simulation wants the simplest solution possible. So, if you use numbers with common factors (like 2 and 4, which both have a common factor of 2), you’ll be told your answer is correct, but you can simplify it further. 14. If you miss a second time, you won’t get points, but you can see the right answer to learn from your mistake. 15. You can always restart a level by going back to the level selection screen at the top. 16. Now, let’s finish this level and see your final score. Remember, practice makes perfect, so keep challenging yourself and complete the other levels! Conclusion This interactive simulation provides students with a comprehensive introduction to balancing chemical equations. Through clear explanations, visual aids, and engaging practice exercises, students gain a solid understanding of the concept and can hone their balancing skills at their own pace.

The title of the Project: Valence shell electron pair repulsion(VSEPR) theory This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part This simulation by PhET allows students to explore and understand the relationship between electron arrangements and molecular geometries. The Model Screen This screen allows you to build your own molecules! 3. Click on the bonding icons to connect single-, double- or triple-bonded atoms to a model. Observe how the molecule’s shape changes as you add atoms. 4. You can add a lone pair of electrons to a model in this simulation. 5.Use the red button to remove atoms and electrons one by one or the yellow button to remove them all at once. 6.Checking the “Electron geometry” and “Molecule geometry” boxes in the “Name” section  displays the predicted molecular and electron shape (e.g., tetrahedral, linear). 7. You can show or hide the lone pairs of electrons by checking the “Show Lone pairs” box in the “Options” section. 8. Checking the “Show Bond Angles” box displays the angles between bonds. See how these angles change as you add atoms. 9. The “Reset” button clears the building area so you can start over. The Real Molecules Screen Let’s switch to the “Real molecules” screen through the navigation bar below. This screen showcases pre-built molecules for you to observe. 11. The central panel displays the chosen molecule’s real-life and model 3D structure 12. The “Name” and “Options” sections provide the same information as in the Model Screen. Virtual experiment: The Gillespie method Now let’s start experimenting. n – number of electron domains around the central atom.  m – number of lone pair electron domains around the central atom.  N₀ -total number of valence electrons on the central atom. Nn – number of electrons donated by neighboring atoms (typically from forming a single bond), each single bond contributes one electron. z – formal charge of the molecule п- number of pi-bonds in a molecule. Table 1. 15. In a “Real molecules” screen, select BF3 from the list and observe its real-life 3D structure. Compare this structure to your virtual model. Does it match your calculations? Try to define other molecules’ geometry. Conclusion This simulation provides a student-centered environment for exploring the fundamental concepts of bonding and molecular shapes. Through building virtual molecules and observing pre-built examples, students gain valuable experience in visualizing and predicting the three-dimensional structures of molecules. This interactive tool serves as a bridge between theoretical concepts and practical understanding, fostering a deeper appreciation for the world of molecular chemistry.

The title of the Project: Molecule geometry This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part This simulation by PhET allows students to explore how atoms bond and the resulting molecular shapes. The Model Screen This screen allows you to build your own molecules! 2. In the center, you’ll see a basic 3D model of a molecule with one central atom and two single-bonded atoms. Click and drag to rotate it. 3. Click on the bonding icons to connect single-, double- or triple-bonded atoms to a model. Observe how the molecule’s shape changes as you add atoms. 4. Use the red button to remove atoms one by one or the yellow button to remove them all at once. 5. Checking the “Molecule geometry” box in the “Name” section  displays the predicted molecular shape (e.g., tetrahedral, linear). 6. Checking the “Show Bond Angles” box in the “Options” section displays the angles between bonds. See how these angles change as you add atoms. 7. The “Reset” button clears the building area so you can start over. 8. Take some time to explore the screen and build various molecule shapes. How many different molecular geometries can you create? Do all of them exist in real life? The Real Molecules Screen Now, let’s switch to the “Real molecules” screen through the navigation bar below. This screen showcases pre-built molecules for you to observe. 9. Click the dropdown menu to choose a molecule from the list to investigate. 10. The central panel displays the chosen molecule’s 3D structure 11. The “Name” and “Options” sections provide the same information as in the Model Screen. 12. Analyze the provided molecules and explain how the number of chemical bonds influences the angles between those bonds. Conclusion This simulation provides a student-centered environment for exploring the fundamental concepts of bonding and molecular shapes. Through building virtual molecules and observing pre-built examples, students gain valuable experience in visualizing and predicting the three-dimensional structures of molecules. This interactive tool serves as a bridge between theoretical concepts and practical understanding, fostering a deeper appreciation for the world of molecular chemistry.

The title of the Project: States of matter: Basics This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part This simulation helps students explore solids, liquids, and gases. The “States” screen Here, you can investigate the characteristics of the three states of matter. 3. Play with the screen. Describe the characteristics (shape, volume, particle motion) of each state (solid, liquid, gas) for the chosen molecule. Use the buttons to display the solid, liquid, or gas form. 4. See what happens when heat energy is added or removed from the container using the slider. 5. Track temperature changes with the thermometer. Change units from Kelvin to Celsius using the dropdown menu. 6. Once you’ve explored all three states, reset the simulation and display water molecules. 7. Pause the simulation to compare the structure of water molecules in solid, liquid, and gas states. The “Phase changes” screen Now, switch to the “Phase Changes” screen to see how temperature and pressure affect the behavior of particles. 9. Choose a substance, like Argon. Use the tools to cause a phase change in this substance. 10. Besides adding/removing heat, you can also move the container lid to cause a phase change.  11. Open the “Phase Diagram” panel to track the current state of matter represented by the particles. 12. Note that increasing pressure to the maximum makes the lid fly off. Use the “Return Lid” button to put the lid back on and particles back in the container. Conclusion Students explored the world of states of matter using this simulation. Now they can describe the properties of solids, liquids, and gases. Students can also explain how temperature and pressure can change the state of matter.

The title of the Project: Reactants, products and leftovers This virtual laboratory is intended for use in chemistry classes on the following topics: Objectives: Practical part The “Sandwiches” screen This screen uses a simplified approach to introduce the concepts. Instead of chemical formulas, it uses familiar objects like bread and cheese to represent reactants and sandwiches to represent the products. By manipulating the quantities of bread and cheese, you can observe how a “sandwich” (product) is formed and how leftover ingredients (unreacted reactants) might remain. This helps grasp the basic idea of reactant ratios needed for a reaction. 2. On the left side of the screen the starting materials for reaction are displayed. You can adjust the quantities of each reactant. 3. The right side shows the products and leftover reactants after the reaction is complete. The number of product molecules is automatically calculated based on the chosen reactants. 4. The reactants and products are separated by an arrow in a chemical reaction. 5. For example, at the top of the screen you can see a sandwich recipe or equation. According to this equation, you need 2 slices of bread and 1 slice of cheese to make one sandwich. 6. Let’s add one more piece of cheese. You will see that it is listed as a leftover, because there should be two more bread slices to make a second sandwich.  7. You can also select a “Meat and cheese” section to make your “sandwich” more complicated. 8. In a “Custom” section you can experiment with different ingredients and make your own equation. You can choose from a variety of bread, cheese, and meat options to create unique sandwich combinations. Note that no matter how many ingredients you  add, the reaction won’t go unless you first define a recipe with at least two different ingredients. The “Molecules” screen Now, switch to the next screen. While the overall layout of the screen stays the same in the “Molecules” section, you now have a menu at the top where you can pick one of three common chemical reactions to explore. The default scenario shows the production of water. 9. On the left, you’ll see hydrogen (H₂) and oxygen (O₂) molecules as reactants. On the right, you’ll see water molecules (H₂O) formed as a product. 10. The coefficients in front of the chemical formulas indicate the number of molecules needed. (e.g., 2 H₂ for every 1 O₂). On the “sandwiches” screen, each ingredient was like a single piece. In real chemical reactions, reactants are usually composed of multiple atoms. Based on this, explain why using just one molecule of hydrogen (H₂) and one molecule of oxygen (O₂) doesn’t produce water and is shown as leftovers. The “Game” screen 11. Move to the “Game” tab. This tab allows you to practice balancing chemical reactions and predicting products. There are three levels with increasing difficulty. You can also challenge yourself by adding a time limit and hide the molecules or numbers by changing the radio button. 12. Level 1: Balancing the Reaction. In this level, the balanced chemical equation is provided at the top.You can adjust the number of reactant molecules using the sliders. 13. Your goal is to manipulate the reactants to achieve a balanced reaction, where the number of atoms of each element is equal on both sides of the equation (represented by the circles above the beakers). Once you think you have achieved a balanced reaction, click “Check” to see if it’s correct. 14. Level 2: Predicting Products: This level provides a set amount of reactants and asks you to predict the number of product molecules formed based on the balanced chemical equation displayed at the top. Use your understanding of the reactant ratio to predict the number of products. Click “Check” to see the actual number of products generated by the simulation. 15. Level 3: Leftover Reactants: This level presents a scenario with a set amount of reactants. The challenge is to predict which reactant will be completely used up (limiting reactant) and which may have leftover molecules after the reaction. Analyze the balanced equation and the initial quantities of reactants to make your prediction. Click “Check” to observe the reaction and see if there are any leftover reactants. Conclusion The PhET simulation “Reactants, Products, and Leftovers” provides a valuable tool for exploring the fundamentals of chemical reactions. Through the interactive screens “Sandwiches” and “Molecules”, students gained a simplified understanding of reactant ratios and how they influence product formation. They also applied their knowledge of balancing chemical equations through the “Game” screen.