Grade 8 Natural Sciences Chemical Reactions WorksheetCloud Video Lesson

good day to you awesome and amazing gradates out there and welcome to our worksheet cloud Natural Sciences listen if you have question during the lesson send an email with your question to grade eights heads worksheet cloud comm my name is mrs. eshton and i'm the web she'd cloud grade 8 natural sciences teacher if you've just joined us this lesson welcome to you it is great to have you with us today and to all our students that have been watching all the lessons welcome back I'm glad you are here I'd love you to be prepared for the lesson so please ensure you have some paper and pens ready any of your books files or notes really think it's important for you to engage in the lesson and not just sit back and listen to what say so be involved work with me write on things as we go pause the video if you need to watch it again or replay anything and look forward to spending this time with you so today we're going to cover new section of work it's all about chemical reactions so we'll have look at what do we mean by what is chemical reaction how do we represent what happens in chemical reaction what do all the numbers or letters or symbols in the chemical reaction mean and how do we translate between word equations pixi picture equations and chemical equations so we're going to start with an activity where we are going to engage you the first thing would like you to do is write down on your page the words see think and wonder and what would like you to do is have provided you with two images here this top one is of sparkler that's burning and this bottom here the process I'm wanting you to have look at is what's this happening with this chocolate so this is actually an icicle that is melting with this droplet here so with the icy that is using your powers of observation and want you to look really carefully at the diagrams and write down everything that you see when you look at these two diagrams and maybe in your notes you can write or split the page into diagram diagram or or sparkler and icicle melting so somehow split your thoughts between these two pictures so think you may need to pause the video now to complete this engaging activity you so we're going to continue to look at the diagrams that we used for see think wonder and let's refer to images and now so firstly if have look at can see bright lights can see an orange white color can see sparks if look at image can see what guess as an icicle it's it's blue she black gray and color can see water droplets at the top of the icicle so is this image showing chemical change or physical change and what do you see or no that makes you say that so if you could pause the video and spend some time trying to answer questions 1 2 & 3 so the sparkler represents chemical change and the Icicle mountain represents physical change would also like us to think about the three levels when we have look at chemical reactions and want you to think about elements compounds and chemical reactions and I'd like you just to jot down these three words and we'll refer to them through the course of the lesson the one word is macroscopic the other word is microscopic and the last term is sub microscopic so to help us understand these terms that you have written down want you to do another activity would like you to draw so basically that means use illustrations or any types of diagrams or sketches or pictures that's come to mind or anything that you can think of when say the word water you can pause the video if you need more time so have to guess what think your drawings look like and I'm sure they are absolutely beautiful and wonderfully creative so this is what think that some of you might have thought of some of you might of thought of glass of water or bottle of water some of you have might've thought of water coming out of tap some of you maybe thoughts of river of water or sea or stream some of you might've thought of water as ice cubes some of you might have thought of water in terms of rain some of you might have thought of water droplets maybe some of you thought of fireman or watering your garden or having shower or washing the car some of you might have thought of using water to cook on the stove or the steam that comes out of kit lower pots of boiling water some of you might have drawn water molecule some of you massive roots in the chemical formula for water age to own and some of you have maybe even drawn water as solid or liquid or gas now all of those answers are absolutely fine because here we are just learning about the difference levels in which you perceive things so the level that we have looked at now initially was probably macroscopic level and what we mean by macroscopic is that you can taste you can touch you can see you can feel you can you can interact with the substance using your powers of observation and using your senses so macroscopic view is going to be for example big reward so we can physically touch smell see and taste the water now sub macroscopic level could be where you used ball diagram to represent molecule so that is what we imagine the molecule to look like or if you represented water in diagram as solid or liquid or gas we are imagining what the particles in solid or liquid or gas look like or we could have represented water at symbolic level so we could have written the word water in terms of word equation or you could have used the symbols that you have learnt from the periodic table so hydrogen we represent using the capital letter and oxygen we represent using the capital letter and we know that when hydrogen and oxygen combine two atoms of hydrogen combine with one atom of water and that makes water molecule so these are all the levels that we can use to represent chemical equation or chemical reaction so one thing you'll be familiar with are the physical changes that take place when we have an icicle melting or block of ice that's melting we know that water exists in three France states so we have the gas molecules in the air as water vapor we have the liquid molecules in terms of in the water and we have the solid molecules in terms of an ice cube so we can represent water using ball diagram where the large red circle represents oxygen and the two smaller white circles represents hydrogen so this is ball diagram that we can use to represent water water is also compound so every single water molecule will look the same there are also forces of attraction and repulsion between the particles of matter and we have learned that each state of matter behaves differently and the particles in each States behave differently but how then could we define chemical reaction if you need to pause the video to copy down the definitions please do so we need to use the words reactants products bonds rearranged molecules or new compounds so I'm going to give you little bit of time to use these keywords and see if you can write definition for chemical reaction for me chemical reaction is rearrangements of atoms in which one or more compounds are changed into new compounds or chemical reaction is arrangements of atoms in which one or more elements can be changed into new compounds so all chemical reactions can be represented by equations and models the one important aspect we need to also have look at is the law of conservation of mass the law of conservation of mass states that in closed or an isolated system matter cannot be created or destroyed it can change from one form to other forms but the mass of the atoms will always be conserved so anytime that atoms separate from each other or anytime that atoms recombine into different combinations of atoms so anytime atoms of compounds recombine to make new compounds or anytime atoms from elements combine to make new compounds we say that chemical reaction has occurred so when we have look at these chemical reactions no atoms are lost no atoms are gained they are simply just rearranged the concepts that I've just covered here is really really important so please make sure that you get this information down so just reminder in mathematical equations you use an equal sign so for example two plus two calls for however in scientific chemical equations please don't use the equal sign we use an error so for example plus o2 arrow which represents chemical reaction has taken place form co2 so carbon plus oxygen undergoes chemical reaction whereby we make the compound co2 so we can look at word equations so in chemical reactions when hydrogen gas reacts with oxygen gas to form water so there's our sentence or our problem how do we turn that into word equation for the reaction so for example we're going to say hydrogen plus oxygen arrow and because chemical reaction produces water so here we have our arrow to the left of the arrow we have our before situation what did we have before the reaction took place and we call that the reactants so hydrogen and oxygen are the reactants that means everything to the right of the arrow so here's our error everything to the right of the arrow is after the chemical reaction so this represents substances after the reaction has happened and we call those items the products so what would you call the products in this reaction yes water then we can have look at picture equations and again please pause the video if you need to get any information down so the chemical reaction of hydrogen reacting with oxygen can also be represented using pictures so the diagram below shows that the atoms of two hydrogen molecules so hydrogen is diatomic molecule which means we represent these circles as two so one circle represents one handsome so hydrogen in its natural state is diatomic h2 so this little two here represents number of accidents so here's one molecule of hydrogen made up of two atoms so there's one molecule of hydrogen and here's one molecule of hydrogen so we have two molecules of hydrogen gas and they react with one molecule of oxygen oxygen is also diatomic molecule which means in its natural state it consists of two atoms so we represent those two elements to the left and then the arrow represents the chemical reaction and these two elements these two atoms recombine and rearrange themselves in chemical reaction to form two water molecules so here is one more top water molecule one water molecule consists of two hydrogen atoms that's the h2 and one oxygen atom here is the red it's the one oxygen atom so if we want to represent the equation with pictures hydrogen atoms are the white circles and oxygen atoms are the red circles so if we go back to our definitions would you say that this is macroscopic so can touch or smell or see or taste the water or is it sub macroscopic so imagine what these molecules are looking like or have used symbols for example the symbols for hydrogen and oxygen on the periodic table so it is sub microscopic am imagining what the particles of water look like so what am wondering is are you able to convert this sub microscopic picture into symbolic one so what is the product of this above reaction so the product is going to be water and what are the reactants the reactants are hydrogen and oxygen wonder if you are able to write out their chemical formula so if we have look at chemical equations when we represent chemical equation in terms of chemical formulas so this is using symbols we call it chemical reaction equation so the chemical equation for making of water is going to be representing hydrogen with the letter from the periodic table oxygen by representing oxygen with from the periodic table in one molecule of hydrogen there are two atoms in one molecule of oxygen there are two atoms in one molecule of water these two atoms of hydrogen and one oxygen but when we represent this equation we need to keep the equation balanced so we have two molecules of hydrogen react with one molecule of oxygen to give us two molecules of water so what kind of representation is this is this macroscopic we can touch it and see it and smell it are we imagining what the products look like or are they really symbols that we can use to represent the elements in the reaction so it is symbolic we still have the reactants on the left the reactants are hydrogen and oxygen we still have our arrow and we still have our products on the right so here is little exercise for you to do have given you some equation reactions on the left hand side of the column wonder if you could tell me what type of equation this is so if you need to pause the video to get the answers down you can but I'm only giving you the answers at the end of the lesson so if we have look at the chemical formula remember that this error represents the reaction everything to the left of the arrow we call reactants everything to the right of the arrow equal products so hydrogen and oxygen or reactants water is the products so what do these numbers mean so the numbers in front represents the coefficients and that represents the number of molecules so here we have two molecules of hydrogen the coefficients is exactly the same in maths we have an invisible one one molecule of oxygen and two molecules of water the subscripts are the numbers at the bottom so hydrogen has got two atoms oxygen has got two atoms hydrogen has got two atoms and oxygen doesn't have no atoms it's an invisible one it has one atom so the subscripts represents the number of atoms so remember the numbers in front of the chemical formula in the equation are called coefficients and they represent the molecules the small numbers inside and below the chemical formula are called the subscripts and they represents the actions so can you write the chemical reaction using pictures words and symbols for the reaction taking place in this diagram okay so need to help you little bit along here we are going to assume that the metal on the sparkler is burning an oxygen and that metal is magnesium so now that you have given you little bit of hint see if you can plan continue writing the pictures words and symbols so here we can use Mack submicroscopic by representing magnesium for the purple circle oxygen which is diatomic so two atoms of oxygen exists together in an oxygen molecule makes magnesium oxide which is one atom of magnesium and two atoms of oxygen so if we have to write us magnesium plus oxygen gives us magnesium oxide and if we use symbols mg plus o2 gives us and here are our answers this equation is picture equation carbon dioxide plus water gives us glucose and oxygen that is word equation here we have picture equation again here we have the use of symbols and numbers that's chemical equation you know we have picture equation again and at the bottom we have chemical equation you are not expected to remember or know any of these equations was just testing do you know the difference between word equation picture equation and chemical or symbolic equation so to summarize this lesson would like you to write down the following chemical reaction and then want you to use words and pictures to m88 this as much as possible so that you have summary of this lesson that you can study from if you have any queries or any questions please remember that you can email your question to grade eights at worksheet cloud.com so this is everything that we this lesson hope that you understood everything that we covered and grenades this lesson couldn't have happened few words out there listening so thanks very much for joining me today and would like to thank worksheet cloud for bringing this lesson to you and reminder if you have any questions please send an e-mail to gradate ads worksheet cloud.com bar grenades