Sunday, April 30, 2006

Grade 9 Science

Need any help understanding what we are doing in class? Need clarification about assignment expectations? Studying on the weekend, and get stuck on a questions? Here's where you can get in touch with me.

52 comments:

Anonymous said...

hi

Nicole said...

Hey Ms. Bearse,
I'm looking through my science review and have no idea about treands in the periodic table. Not a clue. My wonderful friends are also being no help what so ever. None. And neither is the textbook. Should have a note somewhere on this? My big problems are with question 11 & 13 on the chemisty review we worked on in class today.
Nicole (a.k.a. Kissman)

P.S. Though not strictly related to science- my left hand and first finger has swollen up quite a bit...I think perhapes that soccer game did it in. Did I mention I sprained my hand a few weeks ago? Well now it's having a relape...any suggestions?

ms.bearse said...

Nicole,
you need to have a look on the "notes" page and download those. I went over the trends in the periodic table.

I have realized since I printed that review sheet that there are some misprints.

The big deal that you need to realize is that all alkali metals (column/family/group, 1) all have 1 electron in their outer shell. That's 1 valence electron.

alkaline earth metals (column/family/group 2) all have 2 valence electrons.

Boron and Aluminum etc have 3 valence electrons.

Carbon, Silicon etc have 4 valence electrons.

Nitrogen, Phosphorus etc have 5 valence electrons.

Oxygen, Sulfur etc. have 6 valence electrons.

Halogens (fluorine, chlorine etc.) have 7 valence electrons.

Noble gases (Neon, Argon etc) have 8 valence electrons.

That is a trend...all elements in any particular group have the same number of valence electrons.

Another trend that you need to know is that in each period (row of the periodic table) we are working with the same electron shell. As you move toward the right of the periodic table you are adding one electron each time to the shell.

The trend that you need to know about reactivity is that metals are more reactive as you go down the columns, and to the left. Metals tend to donate their electron in order to get a full outer shell. Electrons have a negative charge. Protons have a positive charge. Electrons are attracted to protons. The closer the electrons are to the protons, the stronger the electrical attraction. Metals like Francium have so many electron shells between the nucleus and the valence electron, that the electron is not held so strongly. It can be donated more easily than any other metal.

Non metals are a different story. They tend to accept electrons in order to have a full outer shell. The non metal with the highest reactivity is Fluorine. The nucleus is positively charged, and can attract electrons better with fewer electron shells in the way. Reactivity increase upward and to the right.

I'm sorry about your finger--it got quite a work-out in the game today. My suggestion is to put ice on it, and rest it, and see how it is tomorrow at practice.

Best of luck with the questions.

bill said...

ive got everything on the chemestry review done but i just need to know how to find out how to get the # of neutrons in an element

bill _at said...

done the chen review sheet just need to know how to get the # of neutrons in an element

ms.bearse said...

To find the number of neutrons you need to use the atomic mass and the number of protons.

Remember that the atomic mass is made up of protons + neutrons.

If we know atomic mass and protons, it is easy to find neutrons.

neutrons=atomic mass-number of protons

Hope this helps.

I'm proud of you, getting the review all done. Keep working hard.

Anonymous said...

Whats the constellation project? Is it the one with the myth/legend behind a constellation?

Anonymous said...

I honestly don't see any stars. I've checked two nights in a row. So have other people. I don't see them.

ms.bearse said...

The constellation project (the one that was due today) involved making a constellation viewer out of a tin can (punch holes with a nail) and including a fact sheet about the constellation. Have a look at the notes page on the site, and you can download the requirements.

We are also recording the constellations that we see, and their place in the sky (sky watch project).

ms.bearse said...

Be sure that there are no clouds when you are looking. Also, try to find a place with as little light pollution as possible. I know it's hard with street lights everywhere, but do your best. I've had success sometimes at Winston Field, or in other parks--or by the water. PLEASE don't go out to these dark places alone--it's not safe. Maybe you could convince someone in your family to go for a stargazing walk with you, or go with a group from class.

Write down the location of your observations, and if you can't see stars at that time, record that fact. Hopefully you'll be able to find a good place on a nice night sometime soon. If it remains a problem, we can arrange an extension, or alternate assignment.

Keep me posted.

Anonymous said...

It's gonna rain all week, i think the project is pretty much...well....doomed. :O

Anonymous said...

I have been conscientiously looking for stars. I have found some of the constellations. However, it has been raining almost everyday for the past week. There is no way that I will have 10 observations by wednesday when this project is due. I have done the second half, which is the research part of the project. I've done alot of work on this and i dont want an alternate assignment. What do you suggest?

ms.bearse said...

Well, the project was assigned on may 3rd, so there's a total of 2 weeks of observation time that was available. I know some of the days were rainy, so that's limited some of the observation time. But with 2 observations possible a night, it means only 5 clear nights were needed to get enough data for the project. That being said, if you do not have the data now it's probably going to be hard to complete the project with the rain that's forcasted.

I have an astronomy simulation that can show where stars will be located at different times of the night on particular days. I will bring it to school tomorrow and whoever is interested can stay in at lunch and "stargaze". That's my best recommendation.

Thanks for being pro-active about your project. I'm glad that you're working hard, and striving to get all your work done on time.

Anonymous said...

If you still need to do some sky gazing and unable to due to the rain, just go to http://www.starrynight.com/digitaldownload/trial_download.php
They have a 10 day trial for Starry Night, its a program with all the consteallation and planets etc. You can finish whats left of your sky gazing with this program.

ms.bearse said...

Thanks for the great idea! That program is the one that I have on my computer. I was not aware that they had a trial download available.

Thanks for the helpful comments :)

Anonymous said...

Yo teacher ok, ummm im done all projects and stuff except the gazing, but i wrote down the mythology, i Downloaded the stary night thing (thanks for the thing who ever wrote it). I am going to try to finish it tonight if i dont could i get an extention for friday. Steven by the way.

PS. If you dont read this i'll tell you tomorow

ms.bearse said...

Good for you getting so much work done Steven. Hand in what you can tomorrow, and you can get the rest in on Friday.

Anonymous said...

Ms. Bearse,

Ok science-related question(s) for you:

Electricity doesn’t come from electrons, does it? Wait is electricity more the concept of movement of electrons? Is electricity is generated from the energy electrons have? Do electrons have energy anyways?

Sorry for the number of questions but I don’t really get it. And it’s going to bug me ‘till I understand to. If you can’t explain over the marvelous internet than perhaps explain this stuff some other time that is convenient for you.

Thanks

Nicole

ms.bearse said...

Ok Nicole, you ask great questions!

There are so many misconceptions about electricity. We use that word freely to speak about many many different concepts. Have a look here

We can talk about electricity being the difference in charge between protons and electrons--static electricity

We can talk about electricity as the movement of charge--movement of electrons in wires, movement of either positive or negative ions sometimes too in solutions--this is electric current. (DC direct current)

The electric current in the circuitry of your house is not DC current like that produced with a battery in a circuit. The current in your house is AC (alternating current). It doesnt involve a flow of charge, but a wiggling of charge.

Energy is not created, but it is transformed from one form to another. The movement of a conductor through a magnetic field will make a current flow. Batteries separate charge using chemical energy. The electrical energy is then transferred into other forms (heat, light, sound etc)

Read the website that I linked to, and we'll chat sometime at lunch, ok? I'm glad you're so excited about this stuff! Keep working hard.

Anonymous said...

Just wondering about some stuffs:
1. What decides which object gets the electrons? If you rub a ballon against your hair, what decides if the electrons should go to the ballon or the hair?

2. How does an object regain its neutral status? Does it come back over time or what?

3. If a person was to become totally positive charged through a certain method, will he be able to repel a positively charged balloon w/o touching it?

4. Theoretically, if there was a room with all it's walls positively charged and a positively charged balloon was placed in the center of the room, will the balloon be in suspension? Will the result be different if it was a heavier object?

5. Electrostatic discharge happens when electrons gets exchanged between two objects right? Why is it the spark is so tiny? Is it possible for the spark to be bigger?

ms.bearse said...

Some great questions there!

1. The triboelectric series tells us which materials tend to have a better hold on their electrons. For example, if you rub wool and silk together, the wool tends to lose electrons and become positively charged. The silk accepts the electrons from the wool and becomes negatively charged.

2. First of all it is pretty hard to have an object that is not in contact with anything else. If the charged object is in contact with a material that conducts charge--even a little bit (negatively charged balloon in contact with anything metal for example), the electrons on the balloon will repel each other and spread out causing some to go to the metal until the balloon is neutral.

If anything with charge is connected to ground (a pipe or something that goes down into the earth), then the charge will be neutralized either by extra electrons coming from the ground, or by extra electrons going to the ground. The entire earth is so big that a few electrons wont make a huge charge difference. It is like taking/adding a cup of water to the ocean.

3. Good question--sounds like one for myth busters. It depends on the amount of charge on the person and the balloon. Think of two magnets. You can physically push two north poles of some magnets together, but some have too strong a magnetic field to do so. I wouldn't try getting charged up to such a degree...anyway, the balloon will fall to the ground because of gravity.

4. Theoretically....hmm...similar answer to the question above. You'd need to have a force caused by the electric field that would counteract the force of gravity. You get into questions similar to this in gr.11/12 physics. The force of gravity would increase as the mass of the object increases, so you'd need more charge as the mass increases (all theoretically of course)

5. Electrostatic discharge in the form of a spark happens when the air becomes a conductor due to the electic field. When you have a relatively small potential difference, the spark will be smaller. If you have a really large potential difference (in the case of clouds and the ground it could be millions of volts) the spark will be HUGE, like lightning!

Anonymous said...

ms. bearse, i was just wondering if the review fun sheet you gave us, or posted on the site on june 9th is what to study for the test on monday

ms.bearse said...

For the physics test (which was today for most of you), the material that you should know is really from the exam review for physics. The fun review covers mostly the short answer questions that can be done quickly. There is more analysis required for some of the other questions that you'll see on the test.

Good luck!

Anonymous said...

so should i just study the physisics part of the exam review

ms.bearse said...

that'd be good. Be sure to do some questions that involve calculations, and know how to use the triangles. The triangles will be given to you on the test/exam, so be sure you know what to do with them.

Keep working hard!

Anonymous said...

I don't get it, what is the difference(s) between mitosis and meiosis?

ms.bearse said...

MITOSIS is cell division where the daughter cells (the end result) are identical to the parent cell (the cell that starts the process). Each cell has DNA inside the nucleus. In humans, we have 46 chromosomes. When the cells divide, it is important for each daughter cell to get all of the genetic material, so just before the first stage (prophase) chromosomes replicate (so now we have 2 identical copies of the DNA). The identical halves (sister chromatids) are connected together by a central centromere. It looks a bit like an X shape now. Centrioles are organelles that are involved in cell division. They are in animal cells only. Each animal cell has 2 centrioles. The centrioles replicate before mitosis as well(so we have 2 sets of 2), this allows each daughter cell to end up with 2 centrioles.

Prophase is when chromosomes become distinct, and centrioles begin to travel to the poles of the cell. Spindle fibres begin to form. The nuclear membrane that contains all the chromosomes starts to disintegrate.

Metaphase is when the sister chromatids are lined up along the equator of the cell. The spindle fibres are now connected to the chromosomes.

Anaphase is when the sister chromatids (the halves of the X) separate, and the spindle fibres contract and pull the chromatids apart.

Telophase is when the new nuclear membrane is reformed, and the chromosomes uncoil. The pinching of the cell's membrane, and division of the cytoplasm happens now. The result is 2 daughter cells that have the same DNA as the parent.

MEIOSIS is a process involved in sexual reproduction. The resulting cells are not identical to the parent cells.
Some important things to realize: in sexual reproduction, two parents are involved--each donates 1/2 of the genetic information to the offspring. We know that each human cell has 46 chromosomes. We recieved half from one parent, half from the other. It is important to realize that chromosomes can be grouped in pairs. Homologous chromosomes are two chromosomes that carry genes for the same trait (eg.eye colour), at the same location, but the form of gene could be different (brown vs. blue eyes). In meiosis there are 2 sets of cell division. One set involves the homologous pairs of chomosomes being separated, and then the next set involves the sister chromatids being separated.

So, the steps for meiosis are as follows: before prophase 1, the DNA replicates so we have duplicate copies of the chromosomes, and also the centrioles duplicate.

Prophase 1: The nuclear membrane is gone, and the chromosomes (sister chromatids) are visible. The centrioles migrate to the poles, and spindle fibres start to form.

Metaphase 1: The homologous pairs of chromosomes line up at the equator of the cell. THIS IS DIFFERENT FROM MITOSIS!!! Spindle fibres reach to the chromosomes. At this point, homologous chromosomes can swap some genetic material.

Anaphase 1: The pairs of homologous chromosomes are separated. One of each pair travels to each of the two poles. This step has reduced the number of chromosomes in each cell in half. (the parent had 46, and each daughter cell has 23). This means that each daughter cell will have different genetic material in it...for example, the chromosome with the blue eye gene will be at one pole, and the chromosome with the brown eye gene will be at the other pole.

Telophase 1 involves the formation of 2 daughter cells through the same process as in mitosis. Nuclear membrane reappears, and the cytoplasm is split as the membrane pinches to separate the cells.

Meiosis 2 is similar to the process of mitosis, because the sister chromatids will now be separated.

Prophase 2: involves the nuclear membrane going away, and the centrioles(which have duplicated) migrating to the poles. Spindle fibres are starting to form.

Metaphase 2: involves sister chromatids lining up at the cell's equator, and spindle fibres attaching to the chromosomes.

Anaphase 2: involves the spindle fibres contracting, and the sister chromatids being separated.

Telophase 2: involves the nuclear membrane reappering, and the cytoplasm being split as the cell membrane pinches to divide the cell.

The end result of meiosis in humans is 4 daughter cells. Each daughter cell has 23 chromosomes. Each daugher cell is different from each other. This process allows for variation in a species. Each different egg/sperm combination will result in different characteristics in the resulting organism.

Here is an animation and some other explanations if you want to check it out.

Anonymous said...

Hey Ms. Bearse
What's conception?
What's a scientific model?
How do you find the # of neutrons in an element?
What does atomic # represent?
What does the # of neutrons represent?
what's a mixture and a michanical mixture?
How do you determine the number of neutrons in an element?
What are simple loops?
What are practical applications of static electricity?

ms.bearse said...

What a lot of questions...

Conception is the moment of fertilization, when the sperm meets the egg.

A scientific model is a way of explaining something--a way of viewing a concept. For example, the Bohr-Rutherford model for the atom has a nucleus that is dense and positively charged, and electrons in shells around the nucleus. It was discovered that there is actually a lot of empty space in atoms between the electrons and the small nucleus. Before this model it was thought that atoms were solid masses with + and - charges inside them, kind of like how raisins can be stuck in a hot-crossed bun. Models are generally accepted ways of thinking of things, but they are definitely subject to change, when new information becomes available. They are not "rock solid" like scientific laws.

The # of neutrons is found by using the atomic mass and the atomic number. We know that the only things that contribute significant mass to an atom are the protons and neutrons. So the atomic mass must be the sum of the protons and neutrons. We know that the atomic number tells us the number of protons. So: atomic mass=atomic number+neutrons. We can rearrange that formula, and get neutrons=atomic mass-atomic number.

Atomic number represents the number of protons in an element. In atoms (balanced charge) it also represents the number of electrons.

The number of neutrons tells us how many neutrons there are in the nucleus.

A mixture is anything that is not a pure substance (If you took a small sample, the composition would not necessarily be the same as the original material). A mechanical mixture is a mixture that is easily separated. You can see all the pieces, and could pick them apart if you had to. This is contrasted with a solution, which is also a mixture, but you can't see the individual pieces.

I already answered the number of neutrons question.

Simple loops are circuits that have a battery and a light bulb/resistor and 2 wires. The current goes from the battery through the bulb, and then back to the battery. It's possible to have an ammeter or voltmeter in the loop also to measure different quantities.

Practical applications of static electricity can be found in your text book. There is a paragraph about photocopiers, painting cars, lightning rods etc. Have a look in the book.

Keep working!

Kieran said...

Hello Ms. Bearse

I was going through the science review when i came to the question asking whether or not an electroscope can tell what kind of charge an object has and I don't know the answer. Can you tell me the answer or at least where to find it?

ms.bearse said...

Hi Kieran, an electroscope can tell if an object is charged, but not which kind of charge it has. The electroscope arms will deflect if the electroscope is positively charged, or negatively charged, since both arms would have the same charge, and things with the same charge will tend to repel. So, the answer to your questions is no, the electroscope can't tell what kind of charge an object has, but it can tell if it is charged or not.

Keep working hard!

Anonymous said...

Where do planets come from?
Where do stars come from?

Anonymous said...

hey ms.bears im goin through the exam review and i need help with what an isotope is and how to use the proper notation for writing them.
its bill by the way

Anonymous said...

What is a series load?

Anonymous said...

ms.bears where do stars and planets come from

Anonymous said...

Hey Ms. Bearse, there are 3 questions from the exam Review that i'm not sure about.

1.Explain Practical applications of Static Electricity

These 2 I think I know but I'm just making sure about

2. How can we charge an electroscope if we are allowed o touch it?

3. How can we charge an electroscope if we aren't allowed to touch it?

ms.bearse said...

Stars come from a nebula. They are made of hydrogen gas which comes together becasuse of gravity. As more and more material becomes part of the star the material becomes more and more compressed. Eventually fusion occurs, and the hydrogen fuses together to turn into helium etc.

Planets come from the remains from a supernova explosion, or when the red giant's crust gets blown away by stellar winds. These particles will be attracted together by their gravity, and will collide and stick. Particles will collide into other particles until it becomes a bigger and bigger mass. The collisions heat up the planet, and cause it to have a molten core.

ms.bearse said...

series loads is when you have 2 or more bulbs or resistors in a single loop of wire. The current must go through all of them as it travels from the battery and back.

ms.bearse said...

Isotopes are atoms with different numbers of neutrons. For example Carbon (atomic number is 6, it has 6 protons). Carbon can have an atomic mass of 12 or of 14. The atomic mass is the mass of the nucleus. Atomic mass=neutrons+protons

Carbon-12 has 6 neutrons. Carbon-14 has 8 neutrons. The proper form for writing this notation is with the element name, and then in the upper left corner the atomic number, and the lower left corner the atomic mass.

ms.bearse said...

Practical applications of static electricity could be the lightning rod, or painting a car etc. These are all in the text book--have a look.

Charging electroscopes: CONTACT and INDUCTION

Contact charging is when you can touch it. Electrons will be transferred from one object to another. The electroscope will be charged, so the arms of the electroscope will have the same charge, and repel.

Induction charging is when the electrons are moved within the electroscope, but no electrons are transferred from the charged object to the electroscope, or vice versa. Remember electrons are repelled from negatively charged objects, and are attracted to positively charged objects. Protons are inside the nucleus, so they wont be attracted or repelled anywhere.

Anonymous said...

Dumbquestion, but isn't mixture two different particles? so wouldn't that make compound a mixture, since it has two different particles?

Anonymous said...

Whats Microgravity?

Anonymous said...

Ms.Bearse,

I'm having trouble understanding how to read a voltmeter and ammeter, can you explain it thoroughly? Thanks

Anonymous said...

hi ms.bearse i have a some questions from the exam review that i need help with
1.what are the organelles inside animal and plant cells
2.why is DNA replication important toorganism survival
3.what is budding and spore reproduction
4.do humans have 46 or 96 chromosones
5.what is an ion
6.what is at the center of our galaxie

ms.bearse said...

No such thing as dumb questions!
A mixture is made up of different kinds of particles. If you take a sample of a mixture, the composition of the sample will be different each time. For example, if you have party mix, in one handful you might get 3 raisins, and 2 pretzels, but the next you'd get 4 nuts and 5 raisins and 1 pretzel etc...

With compounds they are made up of one kind of particle. For example, pure water is a compound. You will only find water particles in pure water. Each time you sample the water, you will only find water particles. We know it is pure.

I think the confusion that you are having comes from the idea that compounds are molecules. Molecules are made of atoms that have bonded together. So, we can say that compounds are made of elements that have bonded together.

Let me know if this is not clear yet.

ms.bearse said...

microgravity is any condition with less gravity than we have on earth. You could consider it as the gravity on the moon, or the gravity that you'd feel in orbit (which is really minimal since you are pretty far away from massive objects like planets). The effects of microgravity would be things like your muscles losing tone because they don't need to be used to keep you from falling down as much as they do on earth. Also your bones would become weaker because you wouldn't need such a strong skelleton. If you came back to earth, you'd have some medical problems if you'd been in microgravity conditions for too long.

ms.bearse said...

Voltmeters read the potential difference between two points in a circuit. We usually choose 1 point on one side of a source/load, and one point on the other side. We can then compare the potential between both points. Remember potential is the energy per charge--energy either is added by the battery, or used by the bulb/resistor--

Voltmeters have 4 terminals on them. 1 is negative (black) and it will be connected to the side of the load that is closest to the negative terminal of the battery. We then connect the other side of the load to one of the red terminals.

It is important to know which terminal you are using, because the meter can be read with 3 different scales. The terminal that you plug it into is the maximum number that the scale reads. For example if your termial that you connected to read 5V, the maximum value on the scale is 5V. If the needle is half way across the scale, it would be reading 2.5V.

I hope this helps. Ammeter hook up is the same, but it is always in series with the load. Voltmeters are in parallel with the load.

ms.bearse said...

1. organelles inside animal and plant cells that you need to know:

chloroplasts-in plant cells only-trap the sun's energy and use it for photosynthesis (to make food for the plant)

mitochondria-in all cells-used to convert food into energy that our body can use.

nucleus-the "brain" of the cell, contains the DNA (genetic material)

cytoplasm-the jelly like material that is in the cell

centrioles-the organelle that helps in cell division, they are at the poles when the spindle fibers come out.

2. DNA replication is important because if the cell is going to reproduce itself it needs to duplicate its "brain" so that each new cell can have a complete "brain". If the DNA didn't replicate, each new cell from cell division would only have half the genetic material that it needs.

3. Budding is how sponges and hydra reproduce. It is asexual reproduction. New copies of the organism grow from the side of the old one.

Spore production is how some molds reproduce. Spores are made, and released into the environment. When conditions are favorable, the spores will grow into a new organism. This is also asexual reproduction since there is only one parent.

4. Humans have 46 chromosomes. 23 came from the mother and 23 came from the father.

5. An ion is an atom that has a charge (either positive or negative). It gets the charge from either getting or giving electrons to achieve a complete valence shell. Metals like Lithium and Sodium will form ions by losing the 1 electron that they have in their outer valence shell (draw a bohr rutherford diagram if you are confused). When they lose that electron, they are left with more protons than electrons, and an overall positive charge. Metals all form positive ions.

Nonmetals will need to gain electrons to fill their already almost full outer shell. Halogens already have 7 valence electrons, so need only 1 more electron to be full. When the halogens get the extra electon, they will now have 1 more electron than proton, and will have a negative charge. Non metals will form negative ions.

So: ions are atoms, with charge. They will also have a full outer shell.

6. There is a black hole at the centre of our galaxy. Interesting trivia fact to know! :)

Keep working hard!

Anonymous said...

do we get a peroidic table for the exam?

ms.bearse said...

of course you do! :)

You've gotta know how to use it though.

Be sure to get enough sleep--it's getting late!

katie said...

hey ms bearsie, its katie here and im at my neighbours' house(millers kids) and they wants to say soemthing to ya, anyways, ill say bye and give the keyboard over to them, and ill see you at exam return day...
H i Rachel this is Isi I think you sound nice I would very much like to meet you someday in the crazy future. Katie is very nice and kind and sometimes crazy (he he he)
HELLO!!!!!! Eliza here. I don't think it's getting late!!!! I could stay up all night!YEAH i had lot's of candy at SCHOOL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
hey rachel elisabeth, its me(katie) again and ill go. this is a really long post, so ya. i didn't tell them to say anything, they just said it. anyways, byebye katie( and eliza and isi)

Ms.Bearse said...

Hi girls
you all sound a bit hyper. Have a good weekend.
See you at exam return Katie.
:)