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8th Grade Review Part 1

Added Apr 30, 2019 •

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so now we're going to start the eighth grade review start with scientific method which is just a systematic way for scientist to figure things out what they do is they try to set up controlled experiments so what that means is they change variable in their experiment and only want this is called the independent variable and it's as a change so I light or under slide independent variable why is the scientist change so if to test the effect of playing music on test scores but I am changing is whether or not students listen to music is the day that you measure or you count is dependent on the independent so it's again I'm doing my music during test experiment the dependent variable the test scores control group is what you use to expect what should you use to compare with the experimental group so what do I mean by that well if I knew experiment with students and playing music I would have a group of students who take a test without the music that's the control group the control group is kind of like the before before you start change it Styx Paramount group is the author in which you do is you try to see is there a difference between the before and the after group or the control group and experimental group so don't answer these questions if the problem is does too much water affect plant growth the independent variable is the amount of water the dependent variable is plant growth in the control group would be a normal amount problem is Will temperature of water affect how much goldfish eat independent variable or another word as a scientist change the temperature of the water the dependent variable is how much they eat in the control group is normal water temperature and the control group is the group that does not have perfume on them next if water is heated the more salt will dissolve some independent variable is the temperature of the water my dependent variable measure accounts how much salt is dissolved into control group with the normal temperature water the next thing we're going to talk about is the metric system we're talking about the metric system we got to do King Henry died by drinking chocolate milk drinking chocolate milk or Deka base Desa centi Milli so if I were to have a question and I do want you to write this down that show if I have 4.5 6 a.m. how many what's a millimeter what I have well I'm starting at Sunday so I put my finger here and then move it over to Millie place so decibel one place to the right so be 45.6 and yes I want you to write that down so that's 7 decimal places in converted now talk about what you use so for instance if you're using or try to measure the length of paper you use your volume your mass would be kilograms the volume of a glass of water would be leaders the volume of the fish tank full of water as Leaders the mass of a grain of rice is grams distance from school to the mall to kilometer to miles ran the length of force is written in Newtons acceleration is meters per second squared power is Watts speed in miles per second or meters per second mass is kilogram length is Mater's Thomas II temperature is Kelvin density is grams per milliliter or grams per centimeter cubed and energy is joules remember you are writing down everything that is in red the stage you're going to be it's a black so with graphing what you need to do is just be able to look at a graph and figure out the information so you three grass year the first one is a histogram the second one is a line plot in 3rd scatter plot so answer the following questions you lysing the grass above and graph a how many students are in the 56 to 59 inch rain that would be 12 students how many students are in the 48 to 51 in graph a that would be two students what does Graciela straighten illustrates homework grades how many students have an A in Grass be so right here 3 before what grade do most Germans have in the class in graph be majority have a c what is the label on the x-axis what's the independent variable for grass seed and that is reading what is the label Max's y or the dependent variable x what type of relationship does this show it shows a pause Citi Trend and what's the name of the straight line that is your Trent all right so then we're going to talk about the states of matter solids solids have definite shape definite volume they're tightly packed little energy little basement a liquid has very little space between the molecules a little bit of energy and a little bit of movement it has a definite but it doesn't have a definite shape and gas and plasma gas is a lot of space lots of energy lots of movement plasma is charged gas dad talking about the different processes when you go from a solid to a liquid that is called freezing or liquid to gas is vaporization or evaporation gas to a liquid is called Haitian following liquid to solid is freezing I talked about properties and changes in to do that we're going to watch a little video really great way to learn about science after all he was pretty much just chemistry and chemistry in the signs of different kinds of matter and how that matter can change some of the equipment used in the fire temple timing in measuring both of them in the formation of a mixture example of matter like eggs milk flour and sugar into a tasty dessert different thing like the food stamps can be separated by substances that made that but that's not true about all mixtures sometimes missing things together makes a whole new substance is a chemical change or chemical change change the change that occurs when the particles that make up two or more substances are rearranged to form a new substance or mixture some our picnic chemical changes usually can't be undone let's observe an example of chemical change find this at home we observe a lit match we see that the match Burns as it burns it changes into burn with an ash we can change the sash back into a match so burning is an example of a chemical change that but wait there's more chemical changes how to change color like a blackened remains of the match sometimes chemical changes make smells or at least like or gases and lots of chemical changes require either the giving off or taking in of heat of burning match gives off light smoke antique all of these things are Evan let me look at a burning match we're looking at a chemical change now we can do a simple investigation to show how some chemical changes that can heal this seriously yummy results ingredients of a when we sing together different kinds of matter that you have flour sugar milk and eggs when you put them in a bowl and stir you're mixing several different substances together to make cake batter into the oven after a short time you having you something now before you get it let's check this science cake for evidence of a chemical change should the reaction give off or take heat definitely the case that are needed the heat from the oven to change into take it we let the batter on the counter it would stay batter is there a color change the Bad and the pain was yellow and now it's a nice golden brown is there any smell well if you've never been in a bakery or some Grandma's kitchen or just never smell the cake baking that I feel bad for you because it smells amazing where the gas is released take before and after before we have a wet gooey better after we have a nice fluffy cake as a cake was in the oven some of its ingredients release carbon dioxide gas we can see evidence of carbon dioxide when you cut the finished product all those little Listen to spongy-looking Cake are caused by this gas or last piece of evidence that we witnessed a chemical change this change for example if we want to squeeze it was really hard we get crumbs so let's not try a chemical change is a change that occurs when the particles that make up two or more substances are rearranged to form a new substance most of the time chemical changes Campion and you can tell they're occurring by observing them and noting things like changes in color release Miller Lite and whether they take in or give off heat so the big thing about physical versus properties and changes first of all is that physical properties of property that can be observed without changing the identity of the substance it's just a physical difference it's not what that actually is so for instance if I take a pencil and I break it okay that will be a physical change because it's still a pencil is just a broken pencil so a physical property could be like color of something links that something or the mass of something what are the chemical properties of property that will change that physical change is a change that will form a new substance in a chemical change is a change in which a substance just remember a phase change equals a physical change because 99% of time on the Sol if they're going to talk about changes as it is a physical change in other words it's melting freezing dancing is evaporating then you will still be a physical change the properties color is physical burning chemical white physical hardness physical anytime you see a reaction that can be chemical that chemical reaction boiling point in vaporization physical density physical resting resting actually wear metal turn to rust to knock the rust off by sanding but that metal will never turn back into that Russell never turn back into metal studs chemical change or property determine if the following are physical or chemical changes shopping pencil a physical change again rusting that chemical mixing it's still same thing water and I can separate those so that's the physical change phase change Cora physical melting ice cream price of them were talking about density remembered I heart density mass divided by volume to the top of the heart is the mass the D is for volume of the bottom of the heart so I heart density mass divided by volume alright so it's a physical property the less dense the more floats the more dense the more 6 here is a practice problem a gold brick has the dimensions of 10 cm by 3 centimeters to mass of this gold brick is 1158 for my Mass is 1158 my volume up by three. my next step would say 10 * 3 * 2 which is 60 and then I divide 1158 grams divided by 60 cm and I get nineteen point three percent right next to liquid has a volume of 30 ml and a mass of 16 grams and that gives me 0.5 grams per milliliter so if you want to put these things in a test tube what would be on what the least dense will the least sense of any of them is the salad for is the least sense of anything else so everything then what she was floating on is this point seven liquid or B send the next it would be fortnite which is 3 and then it would be one to see then it's going to be 2.1 or 1 and it's going to be a so that's how they would be a necessity called the least dense the more floats the more deaths two more sink so 4.5 is the most that's why it's on the bottom and you can either start from top or bottom doesn't matter whichever one you want alright so then we need to talk about the classification of matter matter can be divided into pure substances elements found on the periodic table for a compound which is two or more different elements chemically bonded together kind of like a compound word is two simple words put together like doghouse remember asking me to do can't have dog dog and it be a compound it has to be dog house or it can't be oh 2 that would just the oxygen which is an element has to be CO2 carbon and oxygen a compound or if it's not chemically bonded together but it still makes up physically mixed up it's a mixture homogeneous mixtures look like one substance so for instance Kool-Aid to mix up a Kool-Aid one substance and a homogeneous mixture a heterogeneous mixture are mixtures in which you can see all the different parts so like for instance trail mix is a heterogeneous mixture so let's watch this video about the Texas summertime is picnic time sweet salad stuff they're just ask salad are mixtures combine two different things you make a mixture whether it's strawberries and bananas raspberries and blackberries or cantaloupe in Lego switch so what's a little size would a picnic about the different kinds of mixtures we can discover water in a glass will get a mixture even though after a while to send will settle to the bottom of the glass but at least there's some sugar into the water sugar looks like it disappears really doesn't the particles that make up sugar become distributed or spread around evenly among the particles that make up water we call this kind of mixture a solution Solutions of two main parts the song which is the stuff that dissolves in this case the sugar which is the stuff in which the solute dissolved in this case the water oxygen and carbon dioxide and soda water is really salute carbon dioxide gas and liquid water but no matter what and this is important mixing things together and solutions does not make a whole new substance can be separated again sample if you leave the lid off a bottle of soda water the carbon I said that dissolved in the water will slowly float up to the top and bubble away is not mixed together Solutions not all substances dissolve and other substances the ability of something to be dissolved is called its solubility and doesn't dissolve in water solubility in water still dissolve into another thing you'll eventually reached the point where I can't dissolve anymore what Singapore a whole bunch of sugar into a small glass of water or sugar can dissolve this is called saturation supported which no more solute can dissolve into a solution saturation happens when all of this is making me snacking what you going to picnic table again investigate the different kinds of mixtures we see there what starts with a fruit salad that's definitely a mixture of different kinds of fruit is it a solution I can get my spoon in there and come up with nothing but strawberries one time and then go back for more and get a spoonful of only bananas the solution to that question is that it's a solution part of the water and sugar in the tea are evenly distributed in the class everyday contains water brown sugar they're spread out evenly now in the substances that make up our iced tea solution be taken apart again the solution changes from a liquid to a gas so let's go over what we learned that are little mix up picnic mixture is made by combining two or more substances when the particles that make up the substances are evenly distributed the mixture is called a solution solution made of substances that are in the same state of matter like we are three different states of matter like a gas bubbles in soda the solute is the part of the solution that is dissolved in the solvent is the park into which the solute dissolved in Solutions and some other kinds of mixtures don't always make new substances even though it might look that way now listen rest of our picnic before the ants carry it all away pure substances are either elements or compounds mixtures remember you physically combined since you're mixing it up homo genius another word for homogeneous that we heard in the city I was a solution and a heterogeneous they don't fear chocolate will be homogeneous mixture periodic table has the mixture of nitrogen and Italian salad dressing sugar water Lucky Charms heterogeneous texture carbon dioxide carbon is the element oxygen has an element nitrogen now it's into so it's 2 molecules all right so then talking about pH scale anytime you have a pH scale question acid and bases question your pH scale so 1 to 14 with 7 in the middle how do you remember which one comes first what comes first in the alphabet so obvious r127 bases are 7 to 14 anytime you add an acid and base together going to get neutralization which results in water now the farther from 7 the stronger the acid or base is so you have to assets to and for what's the strongest that would be too cuz it's farther away from what's the strongest face 12 or 13 that would be 13 minutes away from 7 underline or highlight acids release hydrogen so don't have a h in the front of them release hydroxide to the beach on the end of it and I was just ran by acid a h b o h bass o h all right so we're supposed to see if he's are acids or bases HCL hco3 again H in the beginning tells you it's an asset NaOH h2-oh space Koh Aloha is your base again Pam let's go through questions a solution with a pH of 3 5 7 9 and 11 first question is what is neither an acid or a base that's neutral or 7 which is the strongest acid SO3 five or your assets three is farthest away from 7 to 3 is your strongest asset which is the weakest acid that's 5 it's closest to 7 which is the strongest base farthest away 11 the weakest base Knights is closest to 7 so then we're going to talk about work versus inorganic compounds organic just me it has carbon if it is a compound that doesn't have carbon its inorganic so this is super easy just recorded alright so CO2 carbon Source organic this is CL this is chlorine this is not Harvest so it's inorganic no carving here in organic organic here's my carbon organic carbon in organic carbon organic no carbon in organic now we need to talk about the periodic table so if you know how to use the periodic table it is the ultimate cheat sheet that you got to know how to use it first of all the periodic table is arranged by atomic mass so as across and down the periodic table the atomic mass increases also the atomic number increases that number is a better way to say is organized now is there an organized in the column these are groups up and down that's a great two this is three four five six seven eight nine 10 when 12 13 14 15 16 17 18 then going across are your. Thank you write a sentence going across the page and at the end of the page you put the right play a sentence across the page in the end of the sentence you put a. Superiors run across the periodic table so that's. One this is. Two three four five now if you just take one little box for instance lithium this will tell you all kinds of things about the atom the smaller of the two numbers is your atomic number that tells you the number of protons lithium has three protons to three what's the atomic number tells you the number of electrons to the first electron shell can hold two electrons in each shell after that can hold hate for it to be. The mass is the bigger of the two numbers and what is an average of the number of protons and neutrons that it contains so lithium has four neutrons how do we figure that out round this decimal 7 + 6 7 - 3 protons 4 neutrons 1 2 3 4 all right so you can now fill these all in that one thing I do need to show you when you go back member of here that staircase staircase everything touching the staircase except aluminum so this is ssssss these are all metalloids K metalloids anyting to the left wood staircase are metals sorry I know my handwriting anything to the right are nonmetals so looking at lithium which is right there Christian is a metal so figure out all these and then we'll check up make sure copy this down pause the video copy Aldi's sale is it on formulas sub below that's a little tiny number the number of atoms in the element before remember there's no subscript that type of atom so for instance here's a subscript for the hydrogen atoms to hydrogen no subscript for sulfur sulfur for is are substrate for off shifts across so figure these out and then check out his first one to iron 3 oxygen 1 calcium 1 sulfur oxygen two hydrogen oxygen to hydrogen sulfur or oxygen 6 carbon 12 6 oxygen binary compounds of binary compounds ions combine to form a neutral compound to all you do is cross applesauce the oxidation number so the one goes here to goes there so too cuz the sodium goes with then reduce it down to your lowest ratio so this is 2 + this is two- how do we get these charges number 1 + 2 + 3 plus or minus for three negative to negative one negative no more that's what we're getting those charges from so magnesium 2 + sulfur is two- we can reduce that down to 1 to 100 hear you go you're the answer happy Thursday ionic versus covalent bonding with watch this year our first lesson is chemical bonding chemical bonds are what holds atoms together by chemical bond is an attraction between atoms that allows the formation of a chemical substance the electrons that participate in a chemical bond are called valence electrons electrons that are found in an atom's outermost shell take a look at the types of chemical bonds that can be formed between atoms anion bond is formed when one of the atoms will lose its electron to the other atom this results in a positively charged ion called A cation and a negatively charged ion is called an anion positive and negative attract and the result is an ionic bond chemical bond involves the sharing of a pair of valence electrons Adam there's also what is called polar covalent bond these are covalent bond in which the sharing of the electron pair is unequal the result to the bonds were the electron-pair is this place more electronegative atom you're watching and we'll see you guys next time so again ionic bond is a bond between a metal and a nonmetal and electrons are lost or gained by a covalent they share sharing so it's a nonmetal and another nonmetal underline where eyes on your wine here write this again ionic is from both ends of the periodic table it's a metal and a nonmetal covalent bonds are two of the same kind to nonmetals so here we go CIA which is somewhere Sam is right here so there's calcium chlorine is right here against sense one from here what is opposite in ionic carbon and oxygen carbon oxygen both the same time both nonmetals so it's a covalent hydrogen even though it's on the metal and it should be on the non-metal in so because of that it actually comes right here so hydrogen-oxygen that's two nonmetals 6 bionic opposite ends one from right here once I'm out here here metal in one from the nonmetal and 6 covalent 7 prevalin a opposite ends so that's why Onnit magnesium oxide ionic hydrogen chloride number hydrogen to trick you on it supposed to be over here and Clarence it's the same time chemical equations the law of conservation of matter which states map simply right Austin at the same number of atoms of an element on the reactant and product side so reactants ouch the left of the arrow products or to the right you just count them up remember we would draw blonde on the Arrow iron is one on this side iron is one on this side on this side anytime you have a coefficient coefficient put your apprentices tribute that so hydrogen is to on the reactant side hydrogen is to on a product site is actually two on the reactant side inquiring as to the products I said this is balanced problems with which ones are reactants and the products and reactants are products so just to see if they're balanced or unbalanced to nitrogen over here to nitrogen over here so that's balanced for hydrogen has two times two is four two times three is 6 hydrogen balance here's my react reacted circling products hey so glad one of her here one over here over here here's to but at still unbalanced DEA barium 112 Corrine recordings or Unbound Lads one lettuce one nitrogen is to nitrogen is to oxygen is 6 oxygen is 3 * 2 is 6 iodine is to iodine is too so we are balanced brighten this last one iron 1 Iron is 1 oxygen is for oxygen is for hydrogen 2 * 482 * 4 don't forget though underline the reactants Circle the fox heart with two types of new energy Vision with a eye that were the nucleus splits this is what happens in nuclear power plants Fusion using two smaller nuclei together this is what happens in the sun right that's it for the first part of the review

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8th Grade Review Part 1

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