[Music] hey all welcome to home school and we are with class 11 chemistry series we started with the first chapter basic concepts of chemistry and under that we have covered the basic introduction about the matter classification of matter and nature of matter and in this video we are starting up with properties of matter properties of matter and their measurements okay their measurements how to measure uh the properties of matter fine and coming to the properties or characters of matter these properties can be divided into two types one is physical properties and the other one is chemical properties clear so let us understand these terms what do you mean by a physical properties say physical properties are those properties which can be measured these properties can be easily measured and they can be observed without changing the composition of matter this is very much important to understand they are observed without changing changing the composition composition of matter clear say for example color color is an example of physical property odour odor in the sense smell boiling point density all these are examples i mean volume all these will come under physical properties say when you want to observe the color of a compound will the composition of matter change say for example this is a chalk piece its composition is calcium carbonate so this chalk piece is made up of calcium carbonate isn't it okay see if i have to observe its color i can just observe this without changing the composition it i it's not that these calcium carbon and oxygens ratio change right say simply without changing the composition uh the property that you can observe is what we call physical properties okay fine and coming to the chemical properties see these chemical properties are observed during chemical change okay a chemical change has to takes place to observe the chemical properties and during the chemical change what happens is composition will change composition will change definitely if a chalk piece is undergoing some reaction definitely what happens uh the ratio of calcium carbon and oxygen in the compound would change calcium and oxygen would become something else it is no more a calcium now it would have converted into something else when this chalk base undergoes a reaction isn't it say that is the difference between physical properties and chemical properties so during physical properties our composition of matter will not change and they are measurable properties you can measure them okay so now what we are going to do is we are learning more about this physical properties okay i said physical properties are measurable properties so what are the properties you call them as physical properties and how do you measure we measure them with the help of si system isn't it so all physical properties can come under seven base physical quantities and let us learn what are the seven base physical quantities and their units okay so i'm talking about seven base physical quantities so why why are we learning these seven base physical quantities because all the physical properties that we are going to measure about a matter will fall under these seven base physical quantities introduced by s i system of measurements okay fine so what are they the first one is mass which can be indicated with the letter m and its unit and its unit is kg yes or no kg in the sense kilo gram clear and the second uh physical quantity is length so length we can indicate with small l and its unit is meter meter can be indicated with small m isn't it and the next one is time time is another base quantity which can be indicated with small t time has a unit called seconds seconds right indicated as small s and the second one is electric current electric current uh which is indicated with i and its unit is ampere ampere a and the next one thermodynamic temperature thermodynamic temperature it's a new word for you don't worry you will understand its meaning little later and its unit is kelvin okay and the next one is amount of substance amount of substance is another physical quantity measured with the help of a unit mole and luminous intensity luminous intensity is another physical quantity where its unit is candela right so these are the seven physical quantities using which we can measure the physical properties of matter clear and along with the basic physical quantities there are some physical quantities like density volume temperature you know all these are derived from these physical quantities and let us try to understand those derived physical quantities also and their units see the very very important derived physical quantity is volume and this volume is very very important in the chemistry because you know most of the gases would combine and that combination is expressed or described with the help of a physical quantity called volume and we say this much cm cube of gas has combined with this much cm cube of gas so volume is the most important uh measurable physical property that we use to describe the matter clear fine so volume and the unit of volume is meter cube but meter cube is not a commonly used unit instead of meter cube we can use a unit called liter okay say for example 10 liters of water i took and i am adding 20 liters of acid you know volume is the most necessary measurable property here so liter is the commonly used unit here and now we all know uh little conversions one liter is equal to 1000 ml isn't it or i can say one liter is equal to 1000 cm cube which is equal to 1 dc meter cube 1 dm cube you know you have to remember all these conversions and these conversions will help us uh during numericals okay say i am giving you the conversions also here clear so that is about the volume and the next to derive the unit is density so what do you mean by a density which is indicated with small d here density is nothing but mass by volume okay and what is its unit mass unit is kg volumes unit is meter cube so kg per meter cube you can write this as kg per meter cube but kg per meter cube is not a commonly used unit in the field of chemistry we normally use uh the unit as gram per centimeter cube so density is unit is what density is unit is gram per centimeter cube here so this is density and coming to the next derived unit that is temperature see guys temperature can be measured with the help of three scales and we call them as degree centigrade degree fahrenheit and kelvin kelvin scale okay and here each and every uh scale of temperature is related to one another and now uh let us see the relation relation between degree centigrade and degree fahrenheit say the relation is fahrenheit is equal to 9 by 5 degree centigrade plus 32 okay and let us see the relationship between degree centigrade and kelvin say kelvin is equal to degree centigrade plus 273 isn't it see all these are not new for us we have already studied this in our previous classes so i'm just you know revising you it's just like a recap for you okay try to understand the relationship between degree fahrenheit and degree centigrade kelvin and degree centigrade so these are the three scales of temperature and the next important derived unit derived physical quantity is pressure so pressure is the most important uh derived unit or with the help of this particular pressure we can describe about the matter clear and specially the gases can be described with the help of this physical property that is pressure fine what is pressure pressure is nothing but force by area say the s i unit of pressure is newton per meter square and pressure can also be mentioned uh in the units like atm or tar okay and let us see a conversion here one atm is always equal to one zero one three two five pascals okay and which is again equal to 760 tar see this is the conversion factor that you can use for pressure if you want to convert atm into pascal pascal into atm or atm into tar tar into atm you know this is what we can use you know you will come to know its use during problem solving in various chapters say i told you know this chapter is a very basic thing uh all the necessary information we will learn in the chapter using which we can understand the next chapters or we use all these things in the next coming chapters okay say now try to remember uh what do you mean by temperature what are the three scales how you can convert them pressures sio units how you can convert from one unit to another unit density volume and etcetera so all these are derived units why do we call them as derived units because these are the units derived from taken from obtained from the seven base physical quantities like mass and then length time all that we studied no seven quantities from them we can extract we can obtain these physical quantities that's why we call them as derived physical quantities and also in case of numericals uh both in the physics and chemistry you know we use certain prefixes okay because we deal with very small numbers say we don't do the reactions uh liters together or kgs together we will conduct the reactions or atoms would combine in a very minute quantities clear so that's the reason there is a necessary thing to learn about the prefixes so let us see what are the general prefixes that we can use in chemistry see guys these are the prefixes used in sr system say for example 10 to the power minus 1 can be called with dc right say some volume of a matter i am measuring and i got the answer as uh 6 deci meter cube right see what do you mean by six dc meter cube six into d they see they see in this sense ten to the power of minus one meter cube so that means uh it is exactly 0.6 meter cube right so this is 0.6 meter cube you can write it as 6 deci meter cube clear everybody so the the meaning of the word small d small d in the sense what deci which is nothing but 10 to the power of minus 1 okay like that we we can also see centimeter is a commonly used unit yes so if i measure a volume of some matter which i got the answer as six centimeter cube so what do you mean by this small c meter cube is a standard si unit for volume we have learnt that say what is the meaning of this is a c in the sense 6 into centi c means what 10 to the power of minus 2 so exact answer is 6 into 10 to the power of minus 2 meter cube like that so instead of writing 10 to the power of minus 2 we can use the word centi uh it can be indicated with the letter small c clear so millimeter like that micro meter say for example i have written 10 nanometer so what do you mean by 10 nanometer here see it's a very small unit small n n means nano isn't it say small n nano that means exactly your answer is tending to 10 to the power of minus 9 meter this is what the meaning of 10 nanometer clear say such a small number 0.008 zeros after that you will get one isn't it say such a small numbers we will deal in chemistry say we can't uh write it as zero point so many zeros it takes lots of space say we are writing it in a small quantities i mean we are taking the help of a prefixes and then we are writing the numbers isn't it say that's why we are learning this prefixes right so you you all know the atoms you know atoms and all are very small in size that we measure them in picometers see hydrogen atom has a size of 300 pico meter can you tell me what do you mean by 300 picometer that means it is 300 into pickup pico means what you see here pico p in the sense pico pico means what 10 to the power of minus 12 meters see 300 into 10 to the power of minus 10 imagine how small the number is 0.000 11 zeros after that your 300 comes say such a small number isn't it so many zeros see that's the reason we take the help of prefixes right so what do you mean by micrometer one micrometer means what one into micro means 10 to the power of minus 6 meter right so this is how we can use the prefixes say we say 100 kg what do you mean by 100 kg it is actually 100 into k in the sense what kilo kilo means what 10 to the power of 3 gram you know this is what the meaning of 100 kg clear say such a big numbers or such a small numbers can be indicated with the help of prefixes so here you must understand what do you mean by hecto hecto is 10 to the power of 2 kilo means 10 to the power of 3 mega indicated with capital m 10 to the power of 6 giga 10 to the power of 9 10 to the power of 12 10 to the power of 15 likewise deci 10 power minus 1 10 power minus 2 is 70 10 power minus 3 is milli 10 power minus 6 is micro 10 power minus 9 is nano 10 power minus 12 is pico 10 power minus 15 is femto so these meanings are very much important to understand right so that's all about the physical quantities uh and the different types of physical quantities derive the physical quantities along with the unit so because these are the measurable properties using these physical quantities you know we can describe the nature of matter so very very important concept especially the units for quantities you have to remember and their conversions see all these we will use during numericals in the next coming chapters so that's the reason we have learnt this in the chapter here so this is one part of a chapter and coming to the next concept it is scientific notation and we will discuss about that in the next video till then take care and do subscribe our channel to learn the concepts in the easiest way and in a detailed way thank you so much [Music] you