00:00 Good day everyone, my name is Adekunle, I will teach you chemistry.

00:17 The topic we have now is particularly nature of matter, follow me as we roll.

00:26 The first is changes of matter, where we have physical change and chemical change.

00:32 What is physical change?

00:33 Is it changed?

00:34 Is it easily reversed and in which no new substance is formed?

00:38 What are the examples of physical change?

00:41 The solution of common sorts in what you know, Masota tomb, when you dissolve it in water

00:45 is an example of a physical change.

00:47 Also, we have change of states, melting, nucleation, solidification, anything that you do

00:53 at home that is so easy to do.

00:57 Those are examples of physical change.

00:59 We also have magnetization and democratization of ion, we have separation of mixtures by

01:04 evaporation, crystallization, and the likes, chemical change.

01:09 It is a transformation in which new substances are usually formed.

01:14 Compared to physical change, whereby no new substance is formed, here also it is not easily

01:19 reversed.

01:23 Many of my friends on the board, in boxing flim, roasting of ion, in most areas, if you check

01:39 very well, you discover that all these changes are not easily reversed.

01:43 The moment they are formed, you can actually get them back.

01:47 Also, reaction of matters and trials carbonate for, which dilutes acids, reaction of alkaline

01:52 atoms and molecules.

01:54 What is atom?

01:55 An atom is the smallest particle of an element, which can tap at in a chemical reaction.

02:00 Atoms of different elements have different shapes, molecule, a molecule is the smallest particle

02:06 of a softness that can also tap at in chemical reaction and is independent of the assistance

02:12 of the reaction.

02:13 The hostility in the chemical properties of that softness compared to atom is the smallest

02:20 particle of an element.

02:22 Five molecules is the smallest particle of a softness.

02:25 Examples of molecules are nitrogen, oxygen, molecule, chloride, sodium, chloride, calcium,

02:32 chloride.

02:33 Sodium channels are naturally 5, and the likes of them.

02:35 The number of atoms in the molecule of element is called atomicity.

02:39 For example, the molecules of the ion, neon, agon, ammonatomic, whereby you can see the

02:46 way they are reaching down, you are not seeing any number.

02:51 Compared to the molecules of hydrogen, oxygen, nitrogen and chlorine that are atomic, you

02:56 can see them by H2, O2, N2.

03:01 The molecule of the zone, for example, O3 is charatomic, it has 3 atoms, and the molecule

03:06 of the spheroes is tetra atomic, it has 4 atoms.

03:10 The molecule of SO4 is polyatomic, having more than 4.

03:14 The nest is Dalton's atomic theory, and according to Dalton in 1808, it proposed some

03:21 theories, which form the basis for atoms.

03:25 The first is all elements are made up of small individual particles, called atom.

03:30 The nest is atom cannot be created nor destroyed.

03:33 Atoms of the same elements are exactly alike in every aspect, and different from atoms

03:39 of all other elements.

03:40 Also, atoms of different elements can combine in small own number, ratio, and the number

03:45 of atoms, not these, says, or chemicals, this results from combination or separation of

03:51 atoms.

03:52 Structural of atoms, there are three fundamental particles of atoms.

03:55 These are protons, neutrons, and electrons.

03:59 Rudar Ford in 1906 discovered that neutron amplitude make up the nucleus of an atom.

04:05 The proton is positively charged, and the neutron is neutral, why the electron is negatively

04:10 charged.

04:11 The proton and the neutron are in the nucleus.

04:14 High electron revolve around the orbits.

04:18 Atoms are electrical in neutral because they contain the same number of electrons and protons.

04:23 What are the characteristics of these subparticles of atoms?

04:27 The first proton, the last electron, and neutron.

04:30 You can see that in the nest line.

04:33 The charge, the mass of proton, is plus 1.

04:37 By that of electron is negative 0.005, which is actually minus 1 over 1,040, and for neutron

04:47 it is zero.

04:51 Atomic number, a mass number.

04:53 What is atomic number?

04:54 This is number of protons present in the nucleus of an element, and it is denoted towards

04:59 z.

05:00 The mass number of an element is the sum of the protons and the neutrons in the nucleus

05:05 of an element.

05:07 It is noted by a, and generally an element is represented as a, if we have an element s, then

05:16 you have n or z to represent atomic number.

05:24 Mass number is usually represented above why atomic number is presented below of the element.

05:31 What is relatively atomic mass?

05:33 The relatively atomic mass of an element is the number of times the average mass of one

05:37 atom of the element is heavier than 1/12, the mass of one atom of carbon 12.

05:43 It has no unit.

05:45 What are isotopes?

05:47 From isotopes, which is the phenomenon, isotopes are atoms with the same atomic number, but different

05:52 mass number.

05:53 This is due to difference in the number of neutrons present.

05:57 As well as elements, it is the different physical properties.

06:00 What this same chemical property because of what the neutron is what causes the differences.

06:07 Examples of isotopes, isotopes of chlorine, which is 36, chlorine and 37, have the same atomic

06:13 number below 17.

06:15 We have three isotopes of carbon, 12, 13 and 14, have the same atomic number of 6, and then

06:20 we have four oxygen, mass, atomic mass, 16 and 17, why atomic number remains 8.

06:28 The rate of atomic mass of an element is the average mass of its various isotopes as

06:34 they occur naturally in any quantity.

06:37 We are going to prove that with chlorine, chlorine 35 and chlorine 37, giving the relative

06:44 abodeances of 75% and 25%, giving chlorine 35 and chlorine 37, with relative abodeances

06:59 of 25% of this and 75% of this.

07:07 You just find the abodeance by saying 75 over 100 times the 35 plus 25% of this 37.

07:25 If you evaluate very well, which I am now having completed with me, you do that.

07:30 You have 26.5, 26.25 here, and then you have 9.35 here.

07:37 If you send them together, you discover the relative atomic mass of chlorine will give

07:43 us 35.5.

07:45 I believe you understand this simple example.

07:49 A isotope is phenomena by atoms of elements are the same atomic number, but different mass

07:55 number.

07:56 The next is empirical and molecular formula.

08:00 What is empirical formula?

08:01 This is the simplest formula, giving the ratios of atoms in the molecular of the compound.

08:05 And what is molecular formula?

08:07 This formula is expressing the correct ratio by mass of the element present, which confirmed

08:12 the relative molecular mass of the compound.

08:14 It actually gave us the actual number of moles of atoms of each element in one mole of

08:19 the compound, as we are going to see with a particular example.

08:29 The compound was found by analysis to contain 65.45% carbon, 9.09% hydrogen, and 25.45% nitrogen

08:40 calculate its empirical formula, follow me as we saw.

08:45 The elements are carbon, the elements are carbon, hydrogen, and oxygen.

08:54 Those are the relative percentages, you have 65.45%, you have 9.09%, and you have 4x

09:08 5, oh sorry, nitrogen, nitrogen, nitrogen, nitrogen, you have 25.45%, denesis you do for

09:25 the mole ratio, you calculate there are mole ratios.

09:29 For carbon, we know that carbon is over 12, hydrogen is over 1, and nitrogen is over 14.

09:36 If you do that, you are going to obtain 5.45% and 9.09% and this is 1.82%.

09:46 The nest is divided by the smallest number, divided by the smallest number, or the smallest

09:58 ratio, which is 1.82, 1.82, divided by 1.82, and what do you get after doing that?

10:09 You are going to obtain 3-year ratio, 5-rissue-1.

10:14 By this you get your empirical formula to C to be carbon-3, hydrogen-5, and nitrogen-1.

10:28 You do not need to write the one day.

10:30 You can see that on the board, clearly I believe, you understand the example.

10:34 The nest is to be able to calculate for the molecular formula, and how do you go about

10:39 this?

10:40 Take this question for example, if the relative molecular mass of the compound is 60, and the

10:45 empirical formula is this, calculate its molecular formula.

10:50 Because you already understand how to calculate the empirical formula, that is why I choose

10:54 to give you the practical formula for the empirical formula, yes, so that you can easily calculate

10:58 for the molecular formula.

11:01 Follow me as we saw.

11:02 Write the molecular mass of the compound is 60, you take that down.

11:09 And the empirical formula is CH2O, calculate its molecular formula, calculate its molecular

11:23 formula.

11:24 How do you go about this?

11:26 That is why I am giving the atomic masses of each element, carbon, hydrogen, and oxygen.

11:32 First, with the empirical formula and your value of n, which are going to determine first,

11:40 empirical formula times n will be equal to the relatively molecular mass.

11:48 This is CH2On, equals to the molecular mass, 60, put the values EA, 12 for carbon, 2 times

12:02 the 1 of hydrogen, plus 16 of oxygen, times n equals to 60.

12:09 If you do this very well, you have 12 plus 2 times 1, which is 2, plus 16, or times n,

12:17 equals to 60.

12:18 I don't know, they're 12 plus 2, give us 14, 14 plus 16, we give us 30.

12:22 So you have 30 n equals to 60, divided both sides by the coefficient of n, which is,

12:34 which is 30, you have to say, by the coefficient of n, which is 30, then EA12, n equals to 2.

12:43 The value of n equals to 2, you will be coupled for your molecular formula, and I'm going

12:48 to go about that.

12:49 Molecular formula is empirical formula times subscript n, and the empirical formula we're

12:57 doing is CH2O times n, what's the value of our n, 2?

13:03 Finally, our molecular formula will simply be C times this 2, H times water times 2, 4,

13:11 n, o, 2.

13:13 I believe you understand that, and you can see that from here.

13:17 The molecular formula is CH2, H4, o2, if you arrange it, you have CH3, C, o, o, H, that

13:24 is a tonic acid.

13:27 Thank you.

13:28 My name is Adekunli, till next time.