chemistry+review+questions

=**Questions ** = =**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 Ivanovich Mendeleev and it is organized by the atomic number. **

2. How is an element different than a compound? give examples.
 * An element is the most simple part of matter. A compound is 2 or more elements combined. **
 * atoms make up molecules and elements make up compounds **.

Example, compound: Water elements: hydrogen (two atoms), oxygen (one atom) compound: Calcium Chloride elements: calcium (1 atom), chlorine (2 atoms) compound: Sodium Bicarbonate (baking soda) elements: sodium (1 atom), hydrogen (1 atom), carbon (1 atom), oxygen (3 atoms)

3. What are the two most abundant elements on the Earth's crust? Silicon and Oxygen

4. What are the two most abundant elements in the human body? carbon and Oxygen.

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

6. Do Hydrogen, lithium, Sodium, and Potassium (H, Li, Na, K) belong to a ** Group ** or **Period** ? (H, Li, Na, K) Explain. Group because each of these elements is found in the first column of the periodic table. They all have +1 valence electrons on the outer shell.

7. Boron, Carbon, Nitrogen, Oxygen, Flourine (B, C, N, O, F) belong to a **Group** or **Period** ? Explain. Periods because these elements all move across a row and gradually increase by one electron as you move across the table.

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

Draw a picture of a Carbon Atom below:
 * the atomic # ||  6 ||
 * the atomic mass || 12 ||
 * number of protons || 6 ||
 * number of neutrons || 6 ||
 * number of electrons || 6 ||
 * valence electrons || 4 ||

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


 * ~ <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">the atomic # ||~ <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">17 ||
 * <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">the atomic mass || <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">35 ||
 * <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">number of protons || <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">17 ||
 * <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">number of neutrons || <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">18 ||
 * <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">number of electrons || <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">17 ||
 * <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">valence electrons || <span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 140%;">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 If you lose an electron, you create a positive ion if you gain an electron, you create a negative ion

the more electrons the larger the cloud and atom

Ionic Bonds that combine compounds like NaCl (Salt) have electrons that are stolen and create ions

11. Would an atom (like Carbon) with a different atomic mass and different number of neutrons be considered an Ion or Isotope? Isotope If you change the number of neutrons, you will change the atomic mass. the charge will remain the same. the kind of atom will be the same. If you have a different number of neutrons in the nucleus, this atom would be considered an isotope.

12. How is a mixture different than a compound? Use both water and mud as your examples.
 * A mixture isn't bonded (like salt and water or mud/water/and dirt) **


 * however a compound is bonded by either a covalent or ionic bond (like chalk, carbon dioxide, water, or salt) **

13. Why would a snowglobe be considered a suspension and not a solution?
 * Because it has not fully bonded. The water and "snow particles" can be easily seperated by a screen or filter. You can also see the particles floating in the water. The particles are easy to see and not dissolved in the water - like salt and water. **

14. Why would a salt mixed in water be considered a solution and not a suspension?
 * Because it is identical through out. It seems like the salt has disappeared in the solution because it is fully dissolved. It would be more difficult to seperate. 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) Glass shattering on the floor 8) a knife being sharpened 9) cheese melted in a sandwich 10) water freezing on an icycle

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

<span style="color: #339966; font-family: 'Comic Sans MS',cursive; font-size: 120%;">This would be an example of cyclic causality because it can always returns back to its original state. For example, water changes in its appearance changing from water to ice. However, the molecular structure of H2O stays the same as it changes into a different state.

17. Give ten different examples of a chemical change.

some examples **6) Baking Soda and vinegar are mixed** **7) A log burns and becomes smoke and ashes** **8) A piece of fruit becomes rotten** **9) Vinegar is added to a cucumber to make a pickle** **10) The statue of liberty becomes green**
 * 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. **

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


 * <span style="color: #800080; font-family: Arial,Helvetica,sans-serif; font-size: 130%;">It would be an domino causality because it would be almost impossible to return back to the original compounds. There is a clear starting point and it moves in a linear direction. For example, when baking soda and vinegar combine, they create a carbon dioxide gas. The carbon and oxygen found in the reactants rearrange and create a new gaseous compound, carbon dioxide that appears as bubbles in the chemical reaction. **

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


 * Sodium and Chlorine combine to make SALT or Sodium Chloride. The compound is created with an ionic bond. **


 * Hydrogen and Oxygen combine to make WATER or H2O. The compound is created with a covalent bond. **

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? <span style="color: #4017d3; font-family: Verdana,Geneva,sans-serif; font-size: 130%;">A catalyst is something that helps to speed a reaction and is usually temperature dependent. The Ninja Gas was created using a catalyst combined with hydrogen peroxide. The hydrogen peroxide then turned into water and oxygen gas. This reaction heated the flask to create an exothermic reaction. The reaction was started by just the right amount of catalyst. Calcium chloride is another catalyst because alters the chemistry of the cheese before the rennet is added.

21. Why would the "gummy bear" explosion in the lab be considered a chemical reaction? <span style="color: #339966; font-family: Tahoma,Geneva,sans-serif; font-size: 130%;">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. This was a combustion reaction because Oxygen fueled this reaction. Potassium Chlorate was heated and Oxygen was released at the bottom of the test tube. The oxygen reacted with the gummy bear to release carbon dioxide, water, heat, and fire. Quite a reaction !

22. What are the reactants in the chemical reaction of photosynthesis?
 * Carbon Dioxide and water **

23. What are the products in the chemical reaction of photosynthesis?
 * Products are sugar and oxygen **

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

paper - Easy to start out with

marble - Its is to make and see how it works

acting it out - Active

What are disadvantages of each model?

paper - Cannot draw the protons or newtrons

marble -messy

acting it out -can get out of control

25. Why is "salt" added to the road in the winter months, when roads are slick and icy? Salt water has a lower freezing point, so the roads won't be as icy In the reverse, the salt added to a beaker of water would increase the boiling point.

26. In the flame test, why is the color of copper chloride a bright blue and the color of lithium chloride bright red?
 * <span style="color: #008080; font-family: 'Comic Sans MS',cursive;">Copper has a blue flame ** <span style="color: #ff0000; font-family: 'Comic Sans MS',cursive;">and lithium has a red flame

<span style="color: #ff0000; font-family: 'Comic Sans MS',cursive;">this is because the difference in the **<span style="color: #4017d3; font-family: 'Comic Sans MS',cursive;">Electrons **<span style="color: #ff0000; font-family: 'Comic Sans MS',cursive;">located on the outer orbital of the atom. Since each element has a different number of electrons on the outer shell, the colors of each element appear different.

27. What two reactions did we see in the upper school that were both Combustion Reactions?
 * Gummy bear reaction and the Magnesium oxide reaction (bright light) **
 * Both these reactions involve a reaction with Oxygen as one of the reactants. **

28. A catalyst helps to change hydrogen peroxide into oxygen gas and water. This was an exothermic reaction. Describe the demonstration.
 * What happened was we added the hydrogen peroxide to the catalyst and it created a chemical reaction. Since it was exothermic, the temperature of the flask increased and got warmer. The products of the reaction were Oxygen Gas and Water. The Oxygen Gas was the smoke rising out of the flask touching the ceiling of the lab. **

29. What two elements were replaced in the chemical replacement reactions in the upper school lab? <span style="color: #0000ff; font-family: 'Lucida Console',Monaco,monospace;">The two elements were copper and aluminum. We put the copper into solution and dropped the aluminum foil into the beaker. The bright blue color of the copper then began to clear up as the aluminum began to be replaced by the copper in solution. At the end of the experiment the copper existed as a solid and the aluminum was part of the solution. Copper and Aluminum were replaced with one another.

30. What are four clear signs of a chemical reaction - use the upper school demos or any of our labs to explain. <span style="color: #bb1b1b; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%;">It looks or feels different, or it emits a odor or sounds

<span style="color: #bb1b1b; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%;">there may be bubbles from a gas formed (like carbon dioxide) <span style="color: #bb1b1b; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%;">there may be a color change (copper turns blue) <span style="color: #bb1b1b; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%;">there may be a temperature change (exothermic or endothermic) <span style="color: #bb1b1b; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%;">there may be a new precipitate at the bottom of the beaker (chalk lab) .
 * Questions:**


 * 1) Change of State Lab**

It is still water even if it is ice or vapor (its still water, regardless of the different state) They move faster and go farther apart It is clear and none poisonous to humans. So many things can dissolve in water. Water actually expands when it freezes (while colder molecules slow down and move closer together) Almost all organisms survive on it. water can dissolve oxygen, carbon dioxide, salt, sugar, etc. So it will freeze at a lower freezing point (see Question 25)
 * Why would you consider a change of state a physical change?**
 * What happens to the molecules of water as they are heated? ( 2 changes)**
 * What are some strange properties of water?**
 * Why is water so important to life on earth? (plants, animals, bacteria, etc. )**
 * Why do trucks put salt on the road when there is a prediction of snow in the forecast?**
 * 1) 2) Mixture Lab (use this lab to answer the questions below)

How is a mixture related to a suspension? powder and water is like a suspension, because both of them are not fully dissolved A snow globe of the NYC would be an example of a mixture, suspension, or solution? suspension Compare a solution and a suspension in the lab? a solution is salt water and a suspension is powder water. You can see particles in the suspension because they do not dissolve How would you separate a solution? evaporate like you would on a evaporation dish for salt ( you can boil all the water to find the salt, too) How would you separate a suspension? use a screen or a filter (like the powder in the lab) What is the difference between a mixture and a compound? <span style="color: #4017d3; font-family: 'Arial Black',Gadget,sans-serif;">A mixture is something where the ingredients are separate, not bonded as a compound they are

What is the advantage of using the data from the entire section compared to the group data? Groups can makes mistakes this makes sure that you are finding the right ratio (3:1 for vinegar to baking soda) What are the reactants in this reaction? baking soda and vinegar What are the products in this reactions? the gas (carbon dioxide) and the new liquid (sodium acetate) What are 4 signs of a chemical reaction? see question 30 What are 4 ways to speed up the chemical reaction? add a catalyst shake the bag or mix the reactants (increase surface area) heat the reactants
 * 1) 3) Ultimate Fizz lab

Is this an example of a physical or chemical change? Chemical
 * 1) 4) Making Chalk Lab

What are the reactants in the reaction? calcium chloride and baking soda What are the products in the reaction? calcium carbonate What is a precipitate?

How does the appearance of salt in the evaporating dish prove it’s a chemical change and not a physical change?

What are other signs that this was a chemical reaction?

Was this an example of cyclic or domino causality?

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)
 * 1) 5) Making Cheese Lab

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?

baking a cake <span style="color: #008080; font-family: 'Comic Sans MS',cursive; font-size: 120%;">chemical ice cube melts into water <span style="color: #000080; font-family: 'Comic Sans MS',cursive; font-size: 110%;">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: 130%;">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: 130%;">Gummy Bear <span style="color: #800080; font-family: 'Comic Sans MS',cursive; font-size: 130%;">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.

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: 120%;">hydrogen peroxide H2O2 + Catalyst

Name the products – <span style="color: #800000; font-family: 'Arial Black',Gadget,sans-serif; font-size: 120%;"> 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: 120%;">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: 120%;">﻿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: 140%;">bubbling (a gas) <span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 140%;">heat or cold temperature change <span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 140%;">a precipitate on the bottom <span style="color: #24b7b7; font-family: 'Comic Sans MS',cursive; font-size: 140%;">color change