1. Elements that are in the same group have more similarities in their properties than those in the same period. For example, Potassium and Lithium both reacted with air and produced gas in water.
2. Elements are very similar in the same group because they have the same number of valence electrons, and all want to lose/gain the same number of electrons.
3. When a sodium atom reacts with a non metal, sodium loses one electron and gets a charge of +1. This now makes it a positive ion. The electron configuration of sodium after reacting is the same as the noble gas neon. Sodium becomes more stable after reacting because it doesn't want to lose or gain anymore electrons, and has a full valence electron shell.
Wednesday, February 15, 2012
Monday, February 13, 2012
Lab 7.2 Periodic Trends Activity
Heavier atoms have more protons and electrons. The protons and electrons are attracted to eachother, so more protons and neutrons means more attraction within an atom. This will make the atom more closely packed together, making the radii smaller.
If an atom is larger, it means there are more electrons in the way of the proton. This decreases the positive attraction, making it harder to attract electrons and decreasing electronegativity.
It is harder to take electrons from non metals as opposed to metals because non metals want to gain electrons, as metals want to lose them.
Nuclear charge is the positive charge an electron has in an atom.
Its called the Periodic Table because there are trends that occur periodically.
If an atom is larger, it means there are more electrons in the way of the proton. This decreases the positive attraction, making it harder to attract electrons and decreasing electronegativity.
It is harder to take electrons from non metals as opposed to metals because non metals want to gain electrons, as metals want to lose them.
Nuclear charge is the positive charge an electron has in an atom.
Its called the Periodic Table because there are trends that occur periodically.
Wednesday, February 8, 2012
Blog 7.1 Flame Tests and Emission Spectra
The spectra of an element is called its fingerprint because they're all different. More specifically, it's their electron configuration when coming out of the excited state into the ground state.
Once a certain amount of energy is absorbed by an element, an electron can jump up a shell. This is called the excited state. It's very unstable in this state and can't stay this way for very long. When it goes back to the ground state, energy is released in the form of light. This pattern of light released is unique to each element and is called a spectra.
Example: 2-8-8 (ground state) 2-8-7-1 (excited state)
Enrichment: Helium was named after Helios, the Greek sun god. A redshift is when light seen is shifted to the red end of the spectrum. Sir Edwin Hubble created Hubbles law, which states all objects observed in space are found to have a wave length shift that correlates with earth.
Once a certain amount of energy is absorbed by an element, an electron can jump up a shell. This is called the excited state. It's very unstable in this state and can't stay this way for very long. When it goes back to the ground state, energy is released in the form of light. This pattern of light released is unique to each element and is called a spectra.
Example: 2-8-8 (ground state) 2-8-7-1 (excited state)
Enrichment: Helium was named after Helios, the Greek sun god. A redshift is when light seen is shifted to the red end of the spectrum. Sir Edwin Hubble created Hubbles law, which states all objects observed in space are found to have a wave length shift that correlates with earth.
Thursday, January 12, 2012
Lab 6.1 Double Replacement Reactions
My predictions were not all accurate. The combination of copper chloride and potassium dichromate did not match up. I thought they would have no reaction, but they did. I would guess that dichromate is the precipitate, even though table F tells us it's soluble.
To write a double replacement reaction:
-Find the charges of every element. These will either be in the periodic table or in tables E and F.
- If there is more than one of that element, add the charges accordingly. (If potassium has a charge of +1, 2 of them will have a charge of +2.)
-Make sure the charges equal out to 0. If they don't, change the number of the elements, not the charges.
- Switch the elements like this: A+B,C+D ---> A+C,B+D
-Check again to see if the reaction is balanced out so the charge equals zero.
- If the question asks you to, find the precipitate. This will be whatever is insoluble in the reaction.
Phosphorous, nitrogen, and chlorine are carcinogen compounds, that can be removed with Ozone. Ozone is generated by passing oxygen through a high voltage and making a third oxygen atom. Ozone is very unstable and oxidizes most organic material it comes in contact with, which is why it's very useful for destroying these carcinogenic compounds.
To write a double replacement reaction:
-Find the charges of every element. These will either be in the periodic table or in tables E and F.
- If there is more than one of that element, add the charges accordingly. (If potassium has a charge of +1, 2 of them will have a charge of +2.)
-Make sure the charges equal out to 0. If they don't, change the number of the elements, not the charges.
- Switch the elements like this: A+B,C+D ---> A+C,B+D
-Check again to see if the reaction is balanced out so the charge equals zero.
- If the question asks you to, find the precipitate. This will be whatever is insoluble in the reaction.
Phosphorous, nitrogen, and chlorine are carcinogen compounds, that can be removed with Ozone. Ozone is generated by passing oxygen through a high voltage and making a third oxygen atom. Ozone is very unstable and oxidizes most organic material it comes in contact with, which is why it's very useful for destroying these carcinogenic compounds.
Thursday, December 15, 2011
Lab 5.1: Alka Seltzer Poppers
In our experiment, we recorded how long it took for a tablet of Alka Seltzer to build up enough pressure to pop the top off of a small canister. We changed around things like temperature, how crushed the tablet was, and the ratio of vinegar and water in the film canister. Our procedure was effective at determining how different variables affected the rate because we made the variables very far apart (For example, instead of putting 24 degrees Celsius and then doing 25 degrees Celsius, we did 0 and then 50.) It was important to keep a control, and only change one thing at a time. If we changed two variables at a time, we wouldn't know which contributed more to the cap popping faster or slower.
A higher temperature made the particles move faster, which gave them a higher chance to collide at higher speeds. The more the tablet was crushed, the faster the reaction rate, because there is more surface area for the vinegar to touch the Alka Seltzer. The more vinegar put in, the faster the reaction rate, because vinegar is a better reactant than water, and the water molecules just get in the way of the vinegar molecules touching the tablets. Our concentration of vinegar in our experiment was not consistent. We thought more vinegar would cause a faster reaction rate. Our data was misleading because we didn't push the top on hard enough, so it didn't create a good seal. Without the seal, air can escape, and not as much pressure will build up.
Enrichment: Sulfuric acid is a catalyst used in real life, It's a highly corrosive mineral acid. It is used in batteries for cares, and for oil refining.
Almost all enzymes are proteins. They speed up chemical reactions by converting substrates into different molecules, called products.
A higher temperature made the particles move faster, which gave them a higher chance to collide at higher speeds. The more the tablet was crushed, the faster the reaction rate, because there is more surface area for the vinegar to touch the Alka Seltzer. The more vinegar put in, the faster the reaction rate, because vinegar is a better reactant than water, and the water molecules just get in the way of the vinegar molecules touching the tablets. Our concentration of vinegar in our experiment was not consistent. We thought more vinegar would cause a faster reaction rate. Our data was misleading because we didn't push the top on hard enough, so it didn't create a good seal. Without the seal, air can escape, and not as much pressure will build up.
Enrichment: Sulfuric acid is a catalyst used in real life, It's a highly corrosive mineral acid. It is used in batteries for cares, and for oil refining.
Almost all enzymes are proteins. They speed up chemical reactions by converting substrates into different molecules, called products.
Thursday, December 8, 2011
Lab 4.2 Heating And Cooling Curves Of Lauric Acid
The melting point of the lauric acid on the given graph was about 45 degrees Celsius. The freezing point of the acid on my graph was around 42 degrees Celsius. These two temperatures should be the same. There may be a slight difference in temperature based on the conditions. It would be extremely difficult to heat a solid above its melting point because the heat that enters the solid at it's melting point is used to convert it into a liquid. Although, you can cool a liquid under its freezing point while staying in liquid form by supercooling it (I researched this a little). A liquid can be supercooled because the particles are packed in an odd way that is not characteristic of the liquid. I got the freezing point from my data by looking where the graph sort of leveled out, because when the substance freezes, it's temperature stays relatively the same for a short time.
Kinetic energy is the energy an object (in this case the lauric acid molecules) has when it is in motion. Temperature is a measure of average kinetic energy, so if the temperature increases, so does the kinetic energy, and vice versa. Since temperature doesn't change during melting or freezing, potential energy is the energy that is gained or lost during this process.
Enrichment: The actual melting point of lauric acid is 43.2 degrees Celsius. Our melting point was recorded at 44.5 degrees Celsius. My percent error is calculated to be 3.01%. This may be because the pressure in the chemistry room may have been slightly different than wherever they recorded the actual temperature. (I'd assume they took it at standard pressure, 101.3 kPa, just to be accurate.)
The chemical formula for lauric acid is C12 H24 O2. Lauric acid is used in the lab to find out the molar mass of a substance, using freezing point depression. Freezing point depression is when the freezing point of a liquid is depressed when another compound is added, which means the mix all together will have a lower freezing point. I got all of this from right here.
Kinetic energy is the energy an object (in this case the lauric acid molecules) has when it is in motion. Temperature is a measure of average kinetic energy, so if the temperature increases, so does the kinetic energy, and vice versa. Since temperature doesn't change during melting or freezing, potential energy is the energy that is gained or lost during this process.
Enrichment: The actual melting point of lauric acid is 43.2 degrees Celsius. Our melting point was recorded at 44.5 degrees Celsius. My percent error is calculated to be 3.01%. This may be because the pressure in the chemistry room may have been slightly different than wherever they recorded the actual temperature. (I'd assume they took it at standard pressure, 101.3 kPa, just to be accurate.)
The chemical formula for lauric acid is C12 H24 O2. Lauric acid is used in the lab to find out the molar mass of a substance, using freezing point depression. Freezing point depression is when the freezing point of a liquid is depressed when another compound is added, which means the mix all together will have a lower freezing point. I got all of this from right here.
Friday, December 2, 2011
Blog 4.1 Fun With Air Pressure
1. A decrease in pressure causes the volume of a balloon to increase. This is because there is less pressure pushing on the balloon, so it is free to expand.
2. Adding more gas to a bottle increases the pressure in that bottle. More gas takes up more space, so in order for the bottle to have all of that gas, it needs to compress it more, thus creating more pressure.
3. As the volume of a cylinder is increased the pressure will decrease. There is more room for the molecules to move around and not be as compressed, so the pressure will decrease.
4. Increasing the pressure in a tire by adding more gas will cause the volume to increase. When gas is in the tire it will inflate a little bit to hold all of the gas, like a balloon.
5. As the temperature of a closed container of water is increased the amount of water vapor above the water causes an increase in vapor pressure. the more gas that is created, the more it will push on the water underneath it.
6. As the air pressure above a liquid is increased by adding more air, the boiling point of the liquid will increase. The higher the pressure, the more energy it takes to boil the liquid.
7. If a balloon filled with air is taken under water to a depth of 10 feet, it’s volume will decrease. This is because of the pressure of the water pushing on the balloon.
8. The temperature of a beaker of boiling water will increase as more heat is added. This is true because temperature is a measure of heat. So if there's more heat, the temperature is higher.
9. Hot air rises because it is less dense the cold air around it. Since it is less dense, its molecules can easily get by the cold air.
10. When heated, the volume occupied by air in a balloon will increase. Heating a balloon would cause the gas molecules inside of it to start moving faster and taking up more space.
Most of my predictions were correct, but some were not. It surprised me that the temperature of the water didn't change when put in the vacuum. I thought the temperature would decrease. What surprised me even more was the fact that it started boiling. Before, I thought you had to have heat in order for liquids to boil.
Enrichment: The workers created a vacuum by sealing off the tanker, with all of the hot steam inside of it. When the temperature dropped, the pressure changed so quickly that it crushed then tanker. This is similar to what we did when we flipped the can with boiling water into the ice water.
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