00:10 Good day students, my name is Uche Ugo.

00:17 I will be teaching basic science and the topic for today is chemical.

00:26 At the end of this teaching, I would respect every one of you to have achieved several objectives.

00:33 The first one is to be able to define in clear terms what chemicals are.

00:40 And secondly, each student should be able to list and describe the various forms

00:48 in which chemicals can exist.

00:51 Thirdly, you should be able to list and describe chemicals based on how hazardous they are,

00:59 whether they are very hazardous, moderately hazardous, or not even hazardous.

01:06 Then the last objective for the day is for each student to be able to discuss the various

01:15 procedures that ensure safety when using these chemicals.

01:20 Now, what are chemicals?

01:24 We say chemicals are substances that have specific molecular composition.

01:32 That is, the molecules within them are very composed.

01:38 If you look at the board, what we have are some liquid chemicals inside a flask.

01:45 Now, a chemical can exist in several forms.

01:49 Now, the first form is whether it is in gaseous, liquid, or solid state.

01:58 Now, the type of state in which the chemical exists depends or determines its movements.

02:07 If it is in a gaseous state, the movement tends to be more random than when it is in a liquid

02:14 or solid state.

02:15 Now, chemicals can also exist in forms based on their complexity.

02:25 So, some chemical substances can be said to be simple, some can say to be more complex.

02:32 Now, for simple chemical substances, we say these substances, when you isolate them

02:39 from other substances, they stand alone.

02:43 That is, their state or situation or their composition is not altered.

02:49 Now, complex chemical substances, they are formed from several or more than one simple

02:58 substances. And when you isolate any of them, they are altered.

03:03 Examples are oxides of salt, sodium, oxides, calcium, oxides, and so on.

03:11 Then, we have your basis or alkaline.

03:14 The base and the alkaline are the same.

03:16 The difference being that an alkaline is a base that has been dissolved in water.

03:21 We also have acids which are complex chemical substances.

03:26 We have organic compounds, some of these organic compounds include your alcohol,

03:32 your paraffin, and your aldehydes.

03:35 Now, chemicals can also exist in another form that is as elements that is single state

03:47 or as compounds or as mixtures.

03:50 Now, what is an element?

03:54 An element is a pure substance made of single type of atom.

04:00 Now, an atom is the smallest unit of an element.

04:05 Elements are building blocks.

04:08 What we mean by building block is that they make up other compounds or mixtures.

04:13 So, everything comes from being a single or everything originated from an element.

04:20 Elements include your ion, which is called FE.

04:26 That's the symbol. We have oxygen, that's your O, we have hydrogen, H, we have gold,

04:32 which is HHG rather than we have helium, your HE.

04:37 Now, this diagram before the screen is a periodic table showing the arrangement of each element

04:48 according to their periodicity.

04:50 Now, we have what's referred to as atomic number.

04:57 It is a very important part of every element because it gives the uniqueness of the element.

05:02 Every atom contains what is referred to as a proton.

05:06 Now, the number of proton in the atom of an element is what we call the atomic number of that

05:14 element. For example, we have a gold.

05:19 Gold has 79 protons in one atom. Therefore, you say its atomic number is 79.

05:26 Now, you need to understand that the number of protons in a particular atom

05:34 is normally equal to the number of electrons except for special circumstances.

05:42 The diagram on the screen is a silicon compound. You can see it is dark gray. This is silicon.

05:51 It is an element. Now, forms of an element.

05:56 Elements come in different forms but they all have the same type of atoms.

06:03 Now, depending on whether it has a high temperature or a low temperature,

06:11 elements can exist in solid, liquid or gearshot state.

06:15 So, we say that if the atoms are tightly packed together

06:22 or their atoms are loose, it determines the level of randomness of their atoms.

06:30 Now, for one carbon present in any particular compound of carbon,

06:40 you have to use it to determine what's referred to as alotrupy.

06:44 Alotrups of carbon talks about the shapes in which carbon can exist.

06:49 Now, we have diamond, which is an alotrupe of carbon.

06:53 We have coal, the popular coal, and we have the graphite.

06:58 Now, the question is how many elements do we have present in the world as are today?

07:06 Generally, studies reveal that there are about 118 elements, but the ones which man has access to,

07:14 which we use to produce or carry out a research are just about 94 of them, families of elements.

07:23 Elements can be grouped according to their properties, so you find that some elements have similar

07:32 properties, and they don't share the same properties with some other elements.

07:37 For example, we have the noble gases.

07:39 Under our grouping, these are referred to as the group 8 elements.

07:45 They consist of elements such as your helium, your neon, your argon.

07:51 They share the same properties, and they are in gearshot states.

07:55 They are referred to as noble gases, and they are uniqueness or the same

08:00 property, which they share is that they are outer shell of their atomic distribution is full.

08:08 For sake of knowledge, the outer shell occupies 8 electrons, and their outer shell is usually filled up.

08:18 We have the alkali-ed metals.

08:24 Now, this set of elements also share the same characteristics.

08:29 We have lithium, we have sodium, we have potassium.

08:33 These are mostly metals that make up your salt.

08:37 They are known to be very reactive, and this is because their outer shell has just one

08:43 electron. It is not filled up.

08:47 We also have some other groups, which include the transition metals.

08:53 We have the non-metals.

08:54 We have the halogens. The halogens are referred to as your group 7 elements.

08:59 That's where you have your chlorine, your fluorine, your bromine, and some other substances.

09:04 We have the alkali-ed metals, we have the actinites, the actinites, the radioactive elements,

09:12 which you use for your bombs, we have the antennites.

09:15 Now, this is a periodic table. Now, as you can see clearly,

09:22 this is the periodic table showing a vertical arrangement of elements that share the same properties.

09:29 I mentioned the group 7 elements. If you move to the group 7, look at this,

09:34 vertically. You find F, which is the fluorine. You see the C, which is the chlorine,

09:39 the 17th element. You see the 35th element, which is bromine,

09:43 the M502, which is the iodine, and some other elements.

09:48 The only two that are no arranged vertically are your lanterites and your actinites.

09:54 Now, what are compounds? The difference between compounds and mixture is that compounds

10:02 are chemically combined. So, they are referred to as two or more chemically combined elements.

10:08 They are bonded. We have what we refer to as bonds.

10:12 Bonds are activities that hold particles of different elements together or elements of the same

10:19 origin together. So, we have different bond types, but the two most useful in this context

10:28 or topic is the covalent and the ionic bond. If you look at this particular diagram,

10:35 this is a diagram of water. So, you see an atom of oxygen. You see two atoms of hydrogen

10:44 on this side, which is H2O. Now, what is covalent bonding? This is a type of bonding that involves

10:54 sharing of electron piers between atoms and it is done in a fixed ratio. Now, we also have

11:03 ionic type of bond. This is a bond that has positive charge on like the covalent bond.

11:12 And in this type of bond, the bond is formed with a negatively charged ion,

11:18 bonding with another type of electron, which is positive, and the form compounds such as your

11:28 commosal sodium chloride, which has an atom of sodium and an atom of chlorine.

11:34 An example of this kind of process of bonding system is the issue of, is the water as the one

11:44 of water. I explained earlier, water has a ratio of two hydrogen to one oxygen. So, it has two

11:53 ratio one. So, that is how it combines in a ratio two to one. We also have table salts,

12:03 which I showed earlier, your sodium chloride. So, the ratio of the sodium ion to the chloride

12:11 ion is one to one. That's why I have NACL. Then we have methane, which is CH4. It's an organic compound.

12:20 So, you have an atom of carbon and four atoms of hydrogen. So, the ratio of hydrogen to the carbon

12:28 is four ratio one. We also have our glucose, which falls under our type of sugar. So,

12:37 the ratio of the hydrogen carbon and oxygen is two, one, one. So, when you give the chemical

12:45 composition of your glucose, you have just one carbon atom, one oxygen atom and two hydrogen

12:53 atom. And you should also note that compounds can be decomposed chemically and they return back

13:00 to the original constituents elements. What are mixtures? Mixtures are materials made up of two

13:09 or more substances. Now, the difference between these compounds is that they are not chemically

13:16 combined. Mixtures are physically combined. Now, we have three forms in which mixed

13:24 materials can occur. We have solutions. We have suspension and we have colloids.

13:32 Now, solution is that type of mixture in which both constituent elements agree with each other.

13:41 That is, they mix conveniently. What do I mean by mix conveniently? This particular mixture

13:50 involves a solute material and a solvent and the form what is referred to as solution.

13:57 Take, for example, what's every one of us, we are used to, that's drinking of Gary. When

14:04 you pour the Gary into the water, it mixes properly to form your Gary solution. That's an ideal

14:11 explanation of a solution. Now, the solvent material is usually liquid and water is the most

14:18 common solvent that helps the solute material to dissolve to form solution. The solvent material is

14:26 usually solid in nature. Suspension is a heterogeneous mixture unlike the solution. So, in this case,

14:37 the solute material which is placed on the liquid does not dissolve properly. Then we have colloid,

14:45 which is the third mixture type. Now, for colloid, the materials which are two or more elements or

14:52 constituent elements are dispersed over a relatively large particle body. Now, you use liquid to

15:00 dispass them either liquid or gas medium, but they are just dispersed. Now, mixture can either be

15:12 homogenous or heterogeneous from the earlier explanation. If you look at the diagram before the screen,

15:18 you find that the homogenous mixtures are uniform. The particles are uniformly distributed.

15:24 Why the heterogeneous mixture? The particles are scattered. Example is the sand in water. The

15:32 particles will be scattered. An example of mixture is your air. We say air is a mixture of gases.

15:42 So, within the air you find gases such as nitrogen, oxygen, and small amount of some other

15:48 gaseous substances. Now, we also have mixture that involves salt, sugar, and some other substances

15:57 that you can mix with water. Those ones are homogenous mixtures. Now, homogenous mixtures involve

16:05 solutes and solvent which are present in solution, and this mixture can have any amount of ingredient.

16:14 Now, mixtures are different from compounds and we can look at some reasons why they are different.

16:24 Now, one of them is being that mixtures can easily be separated physically using

16:32 mixtures such as filtration, freezing, distillation. Then mixture unlike compounds do not require

16:43 high energy level. Then mixtures have various variables and these variables have different

16:53 compositions. Now, for a compound the composition is fixed and they usually have a defined formula.

17:02 Now, for a mixture the properties of the mixture are kept by the constituent substances.

17:10 Whereas in compounds the properties change once the new substance is formed.

17:18 Classification of chemicals. Chemicals can be classified based on how harmful they are to

17:28 animals, man and the environment. The level of harmfulness of a chemical is dependent on the use

17:38 and the composition. Now, how body of organisms absorb these chemicals is what to refer to as each

17:47 hazardous nature. Now, let's look at different chemicals based on their uses.

17:55 The first one is pharmaceutical chemicals also referred to as cosmetics

18:00 and drugs actually. We also have the nuclear chemicals. We have the agrochemicals

18:10 used in agroalite industries. We have industrial chemicals. We also have laboratory chemicals which

18:19 are used in the laboratory. Let's look at them from top, pharmaceutical chemicals.

18:27 These particular chemicals are used to produce certain drugs and cosmetics that help people to

18:35 remedy defects in their living cell tissues. We talk of production of antibiotics. We have the

18:43 antiseptics. We have drugs which can be consumed internally. We also have some herbs.

18:52 So, basically, pharmaceutical chemicals can either be herb or chemically synthesized.

18:58 Now, for nuclear chemicals, we say these particular chemicals are created

19:08 and they act based on their functions in the nucleus of the body which is absorbing them.

19:16 Now, these chemicals can either be split or decayed through a process referred to as radioactivity.

19:25 Now, we have positive or negative uses of these chemicals. Example of its use is estuary which

19:34 is used in hospitals for detecting the sex of a baby. Now, we have agrochemicals. Agrochemicals,

19:41 as the name implies, are those used for agricultural purposes. We have the fertilizers, the organic

19:47 manuals. We have the pesticide, herbicides. Then, the industrial chemicals are divided into two.

19:55 We have those ones which are used in the process of production. Those ones help the

20:02 equipment to function properly. They are like catalysts to boost production. Then, we have those

20:08 chemicals which are the final products of the processes carried out in these industries.

20:15 Now, some examples are the solvents. We have the reactants. We have lubricants.

20:22 Reactants refer to those substances which you use to derive a product. We have lubricants

20:29 for us lubricating materials. We have coatings. Those coatings are what you use for your

20:35 electroplating or coating of other elements like your coating another meta with gold. So,

20:44 it is part good and part of another meta. We have dyes. We have plasticizers. We have colorants.

20:51 We have inks, fragrances for your perfumes, your deodorants and all that. We have conductors and

20:59 insulators. Conductors refer to elements that help conduct whether heat or electricity and

21:07 insulators repair heat or electricity. Then, lastly, laboratory chemicals. They are used in the

21:14 laboratory to carry out research, findings and investigation or investigative procedures.

21:22 Now, some of them are oxidizing acids. We have the inorganic basis or alkaline.

21:30 We have the flammable liquids. We have the cyanides. We have the sulfides. That's your

21:35 acids of your sulfuric acids. We have the inorganic acids and organic base.

21:43 Now, let's look at the classification based on how harmful they are or their hazardous nature.

21:51 The first ones are those ones that are very or highly hazardous. Now, we say hazardous or highly

21:57 hazardous chemicals are those ones that are both toxic and reactive because there are some chemicals

22:05 that are toxic but not reactive and there are some which are reactive but not very toxic.

22:11 Now, the ability for a chemical to be both toxic and reactive causes serious injury to

22:18 human when it comes in contact with them. This can lead to cancerous growth,

22:23 defects in births of children. It can cause genetic alteration which is called induced genetic

22:31 damages, miscarriages. It can even cause deaths. This includes formaldehyde which is used to preserve

22:40 dead bodies. We have chloroform. We have mercury, the green substance which is used in a tamometer.

22:49 We have the refrigerants which is used as your refrigerating coolants. We have the drugs and of course

22:58 your fuel or petrol. The second one are the moderately hazardous chemicals.

23:04 These particular ones are not two hazardous and they are not friendly either. So, they are partly

23:14 hazardous and partly friendly in the sense that their level of toxicity is very low.

23:21 So, what they do is when they come in contact with the human skin they can cause what is

23:26 referred to as irritation. They are very harmful especially to the eyes. They can cause blindness

23:33 and they are used in areas of cosmetics. We have paints used for buildings and metals. We have

23:41 detergents for washing. We have welding fumes which you find in the instruments for welding

23:48 called tongs. We have the degreasers. Now, the non-hazardos chemicals are split into two. We have

23:58 the ones that are known hazardous and non-talksy. Remember I said there is toxicity and there is reaction

24:05 of a chemical. So, we look at the two separately. So, in this case we know that they are not harmful

24:14 and they can easily be flushed down the drains. So, for non-hazardos we have the folic acid which

24:21 we consume for blood to improve the blood in the body. We have your calcium carbonate. We have

24:30 your egg alone. Then, for non-talksy chemicals which have environmentally friendly we have the

24:38 baking soda for which it can be used to deodorize an environment to stop bad odor. It can also be

24:46 used to soften hard water. We have your lemon. The lemon helps to kill bacteria. For example, when

24:53 you have wheatloin in your hand, you use lemon or lime. They kill bacteria, household bacteria.

24:58 And we have the washing soda which is used to remove top stains in fabric materials.

25:06 Now, let's look at the safety measures. Those things which you observe when using these chemicals.

25:14 Now, the first one is that you need to understand the chemical which you are using.

25:21 Understanding the type of chemical which you are using helps you to prepare your hand glove,

25:26 your head, your warmer, whatever you need to deal with this particular chemical, especially if it

25:35 is a hazardous chemical. Also, you need to wear properly your protective gears. For example, in the

25:42 lab, you properly suit up with your lab coat, your hand gloves, your safety glasses that is your eye

25:49 wear. Also, you need to know how to handle this chemical and hazardous chemicals properly so it

25:55 doesn't spill on any part of your body. Then, thirdly, we have some flame-abuse substances that

26:02 needs to be stored properly in a cabinet. Also, you need to learn the measurement or quantity that

26:08 you need to remove depending on what procedure you are carrying out. Also, labeling is very important.

26:15 If a particular bottle for a substance is not properly labeled, you can mistake

26:22 a very flame-abuse substance for a less flame-abuse one. Take, for example, you're trying to do

26:28 a practical and you pick up something that is an acid, thinking it is a base because there is no

26:35 label. It can be very disastrous in the lab. So, you also know how to dispose your waste properly.

26:44 Also, you need to note that hazardous chemicals are not handled on weekends. Being that

26:55 it is very important that you should not be alone in the laboratory and during weekends,

27:00 the likelihood of you being within people who can salvage a particular situation that has

27:08 gone out of hand is very low. So, you should avoid using hazardous chemicals at nights and on weekends.

27:13 Now, you should also know that you should avoid clothing, clothes materials like the one

27:22 called hood that covers the head in the lab, avoid the hood. There is also what's referred to as

27:28 clutter material, be free from clutter, then the floor is very important, most be well cleaned and

27:36 dried so that you don't trip when handling a hazardous chemical. Also, you should make sure that

27:44 you use a film that is ideal so that you don't come to a working environment and what's the perfume

27:54 you are wearing on your body reacts with the hazardous chemical which may be volatile. Also,

28:00 make sure that your hand is washed when you come in contact with a hazardous chemical so that it

28:06 doesn't have irritation on your skin. Now, maintain a good level of contact of the eye

28:17 with your eyes. Also, make sure that your eye is properly washed whenever you finish handling

28:26 a hazardous chemical. Now, you should also make sure you know the position of your shower and the

28:34 exits those of the building in case of danger or explosion of chemicals. It is also important to

28:44 memorize the emergency procedures which is required to evacuate or exit the building at any point in time.

28:52 Also, while you are in the lab, it is encouraged that you do not take cigarettes or any form of

28:59 smoke and do not place anything in form of food in a laboratory. Also, do not apply any form of

29:06 cosmetics because these things can react with a volatile or hazardous chemical. Now, for the sake of

29:15 this teaching, I have drafted some questions which I believe will help you evaluate yourself and

29:22 your level of understanding of the teaching so far. The first question is what does it mean for an

29:29 element to be in its standard state? The second question says what are allotrups of an element?

29:37 Number three question says from the group, the grouping table, that's the periodic table,

29:46 mention the elements that fall under the group 8. Number four question says,

29:53 mention one difference between a covalent bond and anionic bond. Then the last question says

30:01 differentiates between highly hazardous chemicals and moderately hazardous chemicals. Thank you for

30:09 watching. My name is Uche Ugo. Till the next class.