Name: Date: Period: Presentation #4. Covalent compounds continued practice with drawing them. Modeling covalent compounds in 3D

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1 Homework Activities Name: Date: Period: This week we will practice creating covalent compounds through drawings and 3D models. We will also look at polar and non-polar molecules to see how their structures affect their interactions with various molecules. We will end the week by investigating how solubility is affected by factors such as surface area, temperature and pressure. CLASS MONDAY (2/27) TUESDAY (2/28) WEDNESDAY (2/29) THURSDAY (3/1) FRIDAY (3/2) NO SCHOOL Presentation #3 Introduction to Covalent Compounds Presentation #4 Covalent compounds continued practice with drawing them Presentation #5 Polar vs. non-polar molecules Presentation #6 Polar vs. non-polar molecules continued Creating lava lamps Detergent investigation Modeling covalent compounds in 3D Read and annotate p. 2-4, p. 12 p Write a reflection about answer questions on p.5 today s activity. Type it up and finish p. 6-7 and it to me. Answer the following questions: 1.) What is detergent and how does it clean clothes? 2.) How does detergent affect surface tension? 3.) How does detergent affect an oil-water mixture? ALEKS Tutorial on covalent bonding: (type in Chemistry Tutorial 6.01a: How Covalent Bonds Form ) Ionic and covalent bonding animation: (type in ionic and covalent bonding animation 1

2 Warmup- Reflection on Ionic Compounds 1.) Explain how ionic bonding works. 2.) What common physical properties do ionic compounds have? (What do ionic compounds all look like?) Why are they like this? 3.) What do ionic compounds have in common in regards to their melting points are they high or low melting points? Why are all there melting points like this? (Hint- has to do with their ionic bonds). 4.) What happens when you put ionic compounds in water? 5.) What is electricity and why do ionic compounds in water conduct electricity? 2

3 Homework Covalent Compounds Covalent Bonding Overview & Single Bonds Read the following pages and highlight and annotate any important information. Then answer the questions below: 3

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6 Answer the following questions: 1.) On page 2, the text talks about the story of an art project. How does this art project relate to covalent bonding? 2.) Describe what a covalent bond is and what type of elements make covalent bonds. 3.) What type of force holds atoms together in a covalent bond? 4.) What is another name for a covalent compound? 5.) On page 3, there is a diagram of a water molecule at the bottom. Explain why oxygen bonds together with hydrogen (make sure that you talk about the electrons in your explanation). 6.) On page 4, there is a diagram of a water molecule at the bottom. Explain why nitrogen bonds together with 3 hydrogen atoms (make sure that you talk about the electrons in your explanation) instead of 2 hydrogen atoms like water. 7.) Page 4 talks about double and triple bonds. What is a double bond? What is a triple bond? 8.) Look at page 4. Why does oxygen create a double bond with itself? 9.) Look at page 4. Why does nitrogen create a triple bond with itself? 6

7 Drawing Covalent Compounds Use Lewis Dot Structures to show how these covalent bonds form. 7

8 Molecular Compound Electron dot structures Structural Formulas (represent bonds with dashes) # of unshared pairs Type of bonds (single, double, triple) EX: HF There are 3 pairs of unshared electrons 1 single bond between H and F 1.) F 2 2.) H 2 O 3.) NH 3 4.) N 2 5.) CO 2 6.) HCN 7.) HCl 8

9 Warmup Covalent Compounds Read the following information about molecular (covalent) compounds and you ve already learned about the properties of ionic compounds. Fill in the chart below. Properties Ionic Compounds Covalent Compounds Strength of bonds (stronger or weaker?) Typical phases of matter (solid, liquid, gas?) Melting point (high or low?) Dissolves in water (yes or no?) Conducts electricity (yes or no?) 9

10 Practice with Covalent Compounds In this exercise, I want you to figure out what each of these covalent compounds will look like. First, draw the Lewis dot structures and then draw the structural compounds of each (use sticks or lines to represent the bonds between each atom in the compound). 1) SHF 2) CF 2 S 3) BH 3 4) SF 2 5) P 2 H 4 10

11 Modeling Covalent Compounds Build these compounds using the molecular kits provided, draw the Lewis Dot Structures and Structural Compounds (model with lines to represent the bonds), state the type of bonds and give the compound a name. COMPOUND FORMULA Lewis Dot Structures Structural Compound Types of Bonds 1. CO 2 2. CH4 3. HCN 4. C2H4 5. C3H6 6. HCOOH 7. C2H2 8. N2F2 11

12 Homework- Drawing Covalent Compounds Fill in the chart below. COMPOUND FORMULA Lewis Dot Structures Structural Compound Types of Bonds 1. CF 4 2. BF 3 3. NF 3 4. H 2 CS 5. CH 2 F 2 6. O 2 7. PF 3 8. H 2 S 12

13 Warmup- Practice with Drawing Ionic and Covalent Compounds Ionic Compounds Ionic compounds (share or steal?) electrons. Figure out the formulas for the following ionic compounds: 1.) Mg + Br Chemical formula: 2.) Al + Cl Chemical formula: Covalent Compounds Covalent compounds (share or steal?) electrons. Figure out what the following compounds will look like draw the Lewis Dot Structures and the structural compounds (bonds = lines) for each. 13

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15 Blobs in a Bottle (a polar vs. nonpolar molecule lab) [taken from Science Bob at Introduction: You ve already learned about polar and nonpolar molecules and how they react with water. You will now put the polarity principles to work to create a lava lamp and understand how it works. Materials: A clean water bottle of water Vegetable oil Alka seltzer tablets Food coloring Procedure: 1. Pour the water into the bottle. 2. Use a measuring cup, beaker or funnel to slowly pour the vegetable oil into the bottle until it s almost full. You may have to wait a few minutes for the oil and water to separate. 3. Add 10 drops of food coloring to the bottle. The drops will pass through the oil and then mix with the water below. 4. Break a seltzer tablet in half and drop the half tablet into the bottle. Watch it sink to the bottom and let the blobby greatness begin! Data & Observations: What do you notice happening between the oil and the water? What happens when the alka-seltzer tablet hits the water? What does it produce? What happens AFTER the alka-seltzer tablet hits the water? Why is this lab called Blobs in a Bottle? Conclusion: 1. Why don t water and oil mix? Make sure to use polar and nonpolar molecules in your answer. 2. The CO 2 gas produced by the alka-seltzer and water reaction rises to the top of the bottle and carries with it the colored water. When the gas escapes from the top, why does the water sink back down? 15

16 Homework Polar and Nonpolar Molecules Part 1: Identifying Ionic, Polar and Nonpolar Bonds For ionic bonds, the difference in electronegativity (ΔEN) between atoms is. For polar covalent bonds, the difference in electronegativity (ΔEN) between atoms is. For nonpolar covalent bonds, the difference in electronegativity (ΔEN) between atoms is. Use your Periodic Table of Electronegativities to help you figure out whether the following bonds are ionic, polar or nonpolar. Bonds Ionic, polar or nonpolar? Bonds Ionic, polar or nonpolar? 1. Na-Cl 9. Fe- Cl 2. C-S 10. F-F 3. S-F 11. Cr- O 4. N-Cl 12. C-O 5. Fe-S 13. H-H 6. O-Cl 14. C-H 7. Cl-Cl 15. Br-I 8. Si-Br 16. Ca-F Part 2: Identifying Polar and Nonpolar Molecules The following compounds are all covalent. Draw the compounds and figure out whether they are polar or nonpolar covalent molecules. 1.) CS 2 Polar or nonpolar? 2.) SF 2 Polar or nonpolar? 3.) BF 3 16

17 Polar or nonpolar? 4.) CO 2 Polar or nonpolar? 5.) CH 4 Polar or nonpolar? 6.) HCN Polar or nonpolar? 7.) CH 2 Cl 2 Polar or nonpolar? 8.) NF 3 Polar or nonpolar? 17

18 Part 3: Polar and Nonpolar Molecules in Water Here are the following molecules and their structures. Explain what will happen to these molecules when I put them in water will they mix together with water or not? Why or why not? Make sure you talk about polar and nonpolar molecules in your explanation. 18

19 Warmup Polar and Nonpolar Molecules Identify whether these molecules are polar or nonpolar. Explain why. NH 3 BF 3 CH 3 Cl 19

20 The Detergent Lab In class, we ve talked about polar and non-polar molecules and why oil and water don t mix together. Today we are going to explore how detergent works how it cleans our dishes and clothes. Review: In a previous class, you did an experiment where you tested how many drops a penny would hold. What happened during that lab to the penny and the water? Why did you get those results? Predict: Today we are going to see how detergent affects how many drops of water we can fit on the surface of a penny. Make a prediction what do you think detergent will do to the penny and the water? Why do you think that? Method: NORMAL PENNY 1. Get a pipette and a small graduate cylinder filled with water. 2. Drop water from the pipette onto the penny, keeping careful count of each drop. Draw a diagram below showing the shape of the penny just before it overflows. person #1 person #2 person #3 person #4 Average 20

21 EFFECTS OF DETERGENT 1. With your finger, spread one small drop of detergent on the surface of a dry penny. 2. How many drops do you think this penny will hold after being smeared with detergent more, less, or the same as before? Why? 3. Using the same pipette as before, add drops of water to the penny surface. Keep careful count of the number of drops, and draw the water on the penny after one drop, about half full, and just before overflowing. 4. How many drops were you able to place on the penny this time before it overflowed? 5. Record how many drops each person in your group placed on the penny this time. person #1 person #2 person #3 person #4 Average 6. Did the detergent make a difference? Describe the effect of the detergent. 7. What does detergent do to have this effect on water? 8. Explain how detergents act as cleaning agents, considering the cohesion among water molecules and the affects of amphipathic (both polar and nonpolar) molecules. 21

22 DETERGENT, OIL AND WATER Introduction In this activity, we ll see how detergent affects oil and water. Predict: What happens when you put oil and water together why? What do you think will happen when we add detergent to the oil and water mixture? Procedure: 1. Add a few drops of food coloring to the water. 2. Pour about 30 ml of the colored water along with the 30 ml of cooking oil into the water bottle. 3. Screw the lid on tight and shake the bottle as hard as you can. 4. Put the bottle back down and have a look. Let the mixture sit for a couple of minutes and observe. After a couple of minutes, what happened with the oil-water mixture? 5. Now add some detergent. 6. Screw the lid back on the water bottle and shake the bottle as hard as you can. What happened with the oil-water-detergent mixture? 22