chemistry+review+questions

=** cQuestions **= =** you can use the link below for a periodic table to help you answer the chemistry questions : **=


 * Visual Periodic Table **


 * 1. Who created the Periodic Table and how is it organized? **


 * Dmitri Mendeleev created the table and it is organized by it's form vertically and number horizontally, and by periods and groups. **


 * 2. How is an element different than a compound? give examples. **


 * An element is a basic substance of the universe, and a compound is one or more elements combined chemically. **


 * Example, **
 * Compound: Water **
 * elements: hydrogen (two atoms), oxygen (one atom) **
 * Compound: hydrogen peroxide **
 * elements: hydrogen (two), oxygen (two) **
 * Compound: Methane **
 * elements: Carbon, Hydrogen (four) **


 * 3. What are the two most abundant elements on the Earth's crust? **


 * Oxygen (O) and Silicon (Si) **


 * 4. What are the two most abundant elements in the human body? **


 * Oxygen (O) and Carbon (C) **


 * 5. Helium, Neon, Argon, Krypton, Xenon, and Radon belong to what **
 * Group on the periodic table? (He, Ne, Ar, Kr, Xe, and Rn) **


 * Noble Gases (18) **


 * 6. Do Hydrogen, lithium, Sodium, and Potassium (H, Li, Na, K) belong to a Group or Period ? (H, Li, Na, K) Explain. **


 * Group because they are vertically stacked in the periodic table. **


 * 7. Boron, Carbon, Nitrogen, Oxygen, Flourine (B, C, N, O, F) belong to a Group or Period ? Explain. **


 * Period because they are horizontally arranged in the periodic table and their atomic numbers are in order. **

= =
 * 8. Using the Periodic, fill in the table below for the element CARBON. (C) **


 * ** the atomic # ** || ** 6 ** ||
 * ** the atomic mass ** || ** 12 ** ||
 * ** number of protons ** || ** 6 ** ||
 * ** number of neutrons ** || ** 6 ** ||
 * ** number of electrons ** || ** 6 ** ||
 * ** valence electrons ** || ** 4 ** ||


 * Draw a picture of a Carbon Atom below: **




 * 9. Using the Periodic Table, fill in the table below for the element CHLORINE. (Cl) **


 * ** the atomic # ** || ** 17 ** ||
 * ** the atomic mass ** || ** 35 ** ||
 * ** number of protons ** || ** 17 ** ||
 * ** number of neutrons ** || ** 18 ** ||
 * ** number of electrons ** || ** 17 ** ||
 * ** valence electrons ** || ** 7 ** ||


 * Draw a picture or insert a picture of a Chlorine atom below: **


 * 10. Would an atom (like Chlorine) with a different number of electrons (+1 charge) be considered an Ion or an Isotope? **


 * Ion. **


 * 11. Would an atom (like Carbon) with a different atomic mass and different number of neutrons be considered an Ion or Isotope? **


 * Isotope. **


 * 12. How is a mixture different than a compound? Use both water and mud as your examples. **


 * Mixture is when mud is poured into water and creating a suspension. A mixture such as mud and water or powder and water would be easy to seperate. **


 * A compound is put together by a strong bond (ionic or covalent, for example) It would be very difficult to separate a compound that has been formed like Salt (NaCl) or water (H2O) since the electrons create a strong bond between the atoms **


 * 13. Why would a snowglobe be considered a suspension and not a solution?**


 * A snow globe would be a suspension because the particles in the snow globe do not dissolve. The particles are easy to see and floating in solution. **


 * Milk in our cheese lab is a great example of a suspension, as it contains floating protein and fats that do not dissolve in the water. **


 * 14. Why would a salt mixed in water be considered a solution and not a suspension?**
 * 2 answers**


 * a) Salt mixed in water is a solution because salt dissolves in water. **


 * b) Because it is identical through out. It would be more difficult to separate. You could seperate by boiling or using an evaporating dish. **


 * 15. Give ten different examples of a physical change. **


 * some examples: **
 * 1) Aluminum foil is cut in half. **
 * 2) Clay is molded into a new shape. **
 * 3) Butter melts on warm toast. **
 * 4) Water evaporates from the surface of the ocean. **
 * 5) A juice box in the freezer freezes. **
 * 6) Rubbing alcohol evaporates on your hand. **
 * 7) Sugar in water. **
 * 8) HCL dissolves in water to form a pH of 2.0. **
 * 9) Knife being sharpened. **
 * 10) Chalk being broken down into a fine powder. **


 * 16. Would a physical change be an example of Cyclic Causality our Domino Causality? Explain why. **


 * This would be an example of cyclic causality because it can always go back to it's original state **


 * 17. Give ten different examples of a chemical change. **


 * some examples **
 * 1) Rust forms on a nail left outside. **
 * 2) Milk goes sour. **
 * 3) You fry an egg. **
 * 4) Your body digests food. **
 * 5) A match is lit. **
 * 6) Fire burning a log. **
 * 7) Photosynthesis. **
 * 8) Mixing Baking Soda and Vinegar. **
 * 9) Combustion reaction. **
 * 10) Elmo cupcakes being baked in the oven. **


 * 18. Would a chemical change be an example of Cyclic Causality or Domino Causality? Explain why. **


 * Domino because you cannot extract the original element used in the change or the reaction. **


 * 19. How do compounds such as water and sodium chloride (salt) bond together? **


 * Compounds combine because of bonding. Elements are attached by ionic and covalent bonds. **


 * 20. The rennett that was added to the milk when we made mozerella cheese in the lab would be considered a catalyst. What is a catalyst and when did we see another example in the lab? **


 * A catalyst is a substance that causes or accelerates a chemical reaction without itself being affected. We saw a catalyst when we heated water because the water got hotter, but the water still looked like water. **


 * 21. Why would the "gummy bear" explosion in the lab be considered a chemical reaction? **


 * It was domino causality because once you had the explosion, you created new compounds and you can not go back to the gummy bear again. **

^= what did the chemical reaction start with? The reactants in photosynthesis are carbon dioxide, water and light
 * 22. What are the reactants in the chemical reaction of photosynthesis? **


 * 23. What are the products in the chemical reaction of photosynthesis? **

The products in photosynthesis are oxygen and sugar.


 * 24. Models of the atom can be represented on paper, on a marble board, and on a stage. **


 * What are advantages of each model? **
 * paper - You do the whole thing and you see the picture in your own writing. **


 * marble - You have the diagram set up for you and you can see the amount of protons, neutrons, and electrons. **


 * acting it out - You could see the motion of the atom and you could see how many protons, neutrons, and electrons there were like the marble board. **


 * What are disadvantages of each model? **
 * paper - It is harder to understand. **


 * marble - You just place marbles in and nothing else. **


 * acting it out - The diagram can get jumbled and very confusing. **


 * 25. Why is "salt" added to the road in the winter months, when roads are slick and icy? **


 * The salt is added to melt the ice so the cars won't slide and crash. It can also be understood in another way, when you add salt to water, it lowers the freezing point and raises the boiling point. Since it lowers the freezing point, the ice will not be at a cold enough temperature to be in a frozen state, so it will melt. **


 * 26. In the flame test, why is the color of copper chloride a bright blue and the color of lithium chloride bright red? **


 * The elements Chlorine and Lithium both have a different number of valence electrons. The difference in color is due to the difference in the electrons. **


 * 27. What two reactions did we see in the upper school that were both Combustion Reactions? **


 * It was the gummy bear reaction and the magnesium oxide reaction. Oxygen gas is involved in a combustion reaction. There could also be the flame test. **


 * 28. A catalyst helps to change hydrogen peroxide into oxygen gas and water. This was an exothermic reaction. Describe the demonstration. **

The flask in the ninja gas demonstration was hotter and increased in temperature. This difference is because energy was released in the reaction.


 * 29. What two elements were replaced in the chemical replacement reactions in the upper school lab? **

The copper chloride was replaced in this reaction

1) Change in temperature (hotter or colder) 2) bubbles from the gas released in the reaction 3) color change 4) forming a precipitate on the bottom
 * 30. What are four clear signs of a chemical reaction - use the upper school demos or any of our labs to explain. **


 * Questions: **


 * #1) Change of State Lab **


 * Why would you consider a change of state a physical change? **
 * because is is cyclic **
 * What happens to the molecules of water as they are heated? ( 2 changes) **
 * 1). They move faster **
 * 2). They expand **
 * What are some strange properties of water? **
 * Water has the strange property of expanding as it freezes **
 * Why is water so important to life on earth? (plants, animals, bacteria, etc. ) **
 * So many important things dissolve in water that are important to life - like oxygen, carbon dioxide, salt, sugar, minerals, and nutrients. **
 * Why do trucks put salt on the road when there is a prediction of snow in the forecast? **
 * When salt is added to the water (ice) it lowers the freezing point. Ice will not form at 32 degrees F or 0 degrees C **


 * # 2) Mixture Lab (use this lab to answer the questions below) **

This would be an example of a suspension, because there is no materials dissolving.
 * How is a mixture related to a suspension? **
 * A suspension is a type of mixture. In a suspension, particles do not dissolve and are floating in solution. **
 * A snow globe of the NYC would be an example of a mixture, suspension, or solution? **
 * Compare a solution and a suspension in the lab? **
 * solution is salt and water **
 * suspension is powder and water **
 * milk is a suspension **
 * How would you separate a solution ? **

evaporation or boiling mixture is easy to seperate compound is bonded together and difficult to get back to its original
 * How would you separate a suspension? **
 * What is the difference between a mixture and a compound? **

the class average should be more accurate baking soda, vinegar carbon dioxide, water, sodium acetate temperature change bubbles color change precipitate Mix and stir (increase the surface area) heat use a catalyst increase the concentration
 * #3) Ultimate Fizz lab **
 * What is the advantage of using the data from the entire section compared to the group data? **
 * What are the reactants in this reaction? **
 * What are the products in this reactions? **
 * What are 4 signs of a chemical reaction? **
 * What are 4 ways to speed up the chemical reaction? **
 * Is this an example of a physical or chemical change? **
 * #4) Making Chalk Lab **

water, baking soda, calcium chloride water, salt, chalk, and carbon dioxide <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 17px; line-height: 25px;">carbon dioxide gas, temperature change, precipitate on the bottom <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 17px; line-height: 25px;">cyclic causality <span style="color: #777708; font-family: Tahoma,Geneva,sans-serif; font-size: 130%;">Milk used in the experiment is a suspension. <span style="color: #777708; font-family: Tahoma,Geneva,sans-serif; font-size: 130%;">the catalyst rennett was added at exactly 31 degrees C. The rennet speeds up the reaction. The milk turns into both curds and whey. This is a chemical reaction. After the reaction, the curds are separated from the whey and heated into the microwave. When the cheese because almost too hot to touch, the "cheese" becomes stretchable and can be molded into Mozerella Cheese. <span style="color: #777708; font-family: Tahoma,Geneva,sans-serif; font-size: 17px; line-height: 25px;">citric acid is added at the start of the process. <span style="color: #777708; font-family: Tahoma,Geneva,sans-serif; font-size: 17px; line-height: 25px;">the rennett will only work if the temperature is 88 degrees F <span style="color: #777708; font-family: Tahoma,Geneva,sans-serif; font-size: 17px; line-height: 25px;">the milk must be raw milk (not pasteurized) Heating the milk at high temperatures alters the state of the milk and makes it hard to form the curds.
 * What are the reactants in the reaction? **
 * What are the products in the reaction? **
 * What is a precipitate? **
 * <span style="color: #15529e; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">after a chemical reaction, there may be a solid at the bottom of the beaker. In the chalk lab the precipitate was the newly formed calcium carbonate or chalk. **
 * How does the appearance of salt in the evaporating dish prove it’s a chemical change and not a physical change? **
 * <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 17px; font-weight: normal; line-height: 25px; margin: 0px; padding: 0px;">The NaCl at the start of the experiment was the same NaCl at the end of the experiment. Nothing changed chemically. **
 * What are other signs that this was a chemical reaction? **
 * Was this an example of cyclic or domino causality? **
 * #5) Making Cheese Lab **
 * Use the chemistry terms in the entire unit to explain what happened chemically during the cheese making. **
 * (suspension, catalyst, chemical change, reactants, products, curds, whey, rennet, calcium chloride, non pasteurized milk) **
 * What specific variables determine whether the cheese will form or not? **
 * (what could make it not work properly?) What specific steps need to be taken? **
 * know examples of chemical and physical changes **
 * Are the following chemical or physical? Domino or Cyclic? **

know examples of chemical and physical changes Are the following chemical or physical? Domino or Cyclic?

baking a cake <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px;">chemical ice cube melts into water <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px;">physical

photosynthesis <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical pencil is sharpened <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical

sugar dissolves in water <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical combustion reaction (gummy bear) <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical

log is burning <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical water boiling <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical

mixing sand and water <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical making a grilled cheese sandwich <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical

digesting food in the stomach <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical biting into an apple and chewing <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical

making mozzarella cheese <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical baking soda + vinegar = bubbling <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical

making chalk <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical rusting of metal outside in the rain <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 16px; line-height: 23px;">chemical

breaking a cracker in soup <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical grating cheese for a pizza <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 14px; line-height: 21px;">physical

US Chemical Change Demonstrations

a) Why do different compounds react together? (magnesium and oxygen, for example)

<span style="color: #4017d3; font-family: Georgia,serif; font-size: 17px;"> Compounds will react because of the number of valence electrons. Magnesium has 2/8 electrons on the outer shell. Oxygen has 6/8 electrons on the outer shell. Like a puzzle, the two atoms fit together nicely. When bonded, the compound is more stable because the electrons in the outer orbital are full.

b) What is a combustion reaction? We saw two different examples ..

<span style="color: #800080; font-family: 'Comic Sans MS',cursive; font-size: 17px;"> Gummy Bear <span style="color: #800080; font-family: 'Comic Sans MS',cursive; font-size: 17px;"> Mg + Oxygen reaction (bright light)

In a combustion reaction the gas Oxygen is involved and released lots of energy in the chemical reaction.

Is a combustion reaction cyclic or domino? Explain why.

**A combustion reaction is an example of domino causality because once the reaction happens you can't get it back.**

c) Why were the flames all different colors in the flame test?

c) What happened in the Copper Replacement reaction?

e) When making the Ninja Gas . …

Name the reactants – <span style="color: #800000; font-family: 'Arial Black',Gadget,sans-serif; font-size: 16px;"> hydrogen peroxide H2O2 + Catalyst

Name the products – <span style="color: #800000; font-family: 'Arial Black',Gadget,sans-serif; font-size: 16px;"> water H20 and 02 (oxygen gas)

How was this a chemical change or domino causality?

<span style="color: #bb1b1b; font-family: Arial,Helvetica,sans-serif; font-size: 16px;"> Chemical change because new elements are formed in the reaction. It would be difficult to reverse the reaction.

The temperature of the beaker was hot. Was this an endothermic or exothermic reaction? <span style="color: #bb1b1b; font-family: 'Comic Sans MS',cursive; font-size: 16px;"> ﻿the temperature increased as the flask felt much warmer. An increase of temperature is EXOTHERMIC. Think Exo or Exit. The energy is being released and making the water warmer.

f) What are four major signs of a chemical reaction – What did you see in the demos?

**<span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 18px;">bubbling (a gas) ** **<span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 18px;"> heat or cold temperature change ** **<span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 18px;"> a precipitate on the bottom ** **<span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 18px;"> color change ** **