Periodic Table Structure: Periods, Groups, Metals, & Metalloids Explained

hello everyone and welcome back this is Mr kovalt and in this video we're going to be talking about the structure of the

periodic table so what we need to talk about is this word

periodic so periodic means that there's something that occurs at regular or predictable intervals so something that

repeats over and over again uh like for example the the The Swinging back and forth of a of a pendulum is considered

periodic things like that so we're going to look at what is periodic in the periodic table

so when we're talking about periodic law um what we mean there is that there are physical and chemical properties of of

the elements in the periodic table that are periodic meaning there's a repeating pattern

so this repeats by atomic number okay so we're going to see that pattern later on so the periodic table of

elements is arranged by atomic number and this shows patterns in the properties

okay elements so let's uh talk a little bit about elements let's remind ourselves what an element is an element

is one of those pure substances remember there's two categories of pure substances there's elements pure there's

elements and then there's also compounds so elements is one of those categories of pure substances there's only one kind

of atom so you as long as you have only one kind of atom you've got an element it could be bonded together in in a

molecule like O2 and H2 or P4 or S8 so even though they are bonded together in a molecule it's still one kind of

atom bonded together and so it's a pure substance and an element okay so these cannot be broken down into

simpler substances uh because you only got that one kind of atom to break it down further would be basically to

destroy the atom and not have an element anymore so 90 of the elements occur naturally on

Earth so the first 90 are going to be naturally occurring

and then 25 of these were synthesized or made by scientists in the lab so you you make these kind of like in

the super collider uh the Hadron Collider uh will are is a place where these elements can be synthesized

okay let's talk about the periodic table and the first name that you should know is Dimitri

Mendeleev so Dimitri Mendeleev it was a Russian scientist

so he was around in the 1860s and he grouped the elements according to atomic masses and properties so he took the

information that was that was gathered by other scientists he kind of put together and he decided to kind of

organize and group elements according to their properties and then ordered his table according to Atomic massive so

everything was kind of ordered according to the mass of the elements today the periodic table is ordered by atomic

number but he he ordered it by atomic mass so

uh so then uh he created his own periodic table and this is the periodic table

that he originally set up so um you could see that it is in German um and so you could see here

that the elements here are ordered you have sodium here you have

lithium sodium beryllium boron carbon nitrogen oxygen fluorine so it's kind of you got

hydrogen and lithium here but you got beryllium in this grouping here and then you got magnesium so his groupings are

kind of across so brillium magnesium so it's kind of hard to see a little bit of what his table was doing

but you will notice that there are these question marks in the table they're like gaps or holes in his table

so why do you think these question marks are here so mendeleev's table allowed him to make

predictions so those holes in the table had to be filled so Mendeleev based on the pattern of his periodic

table and what he saw the way he arranged it he said that those holes should be filled so there should be some

elements out there that are missing that we need to discover they're waiting to be discovered so mendeleev's table

uh had those gaps but he was able to predict the characteristics of these missing elements based on the

periodicity or the periodic law that he noticed in the table so for example on the left hand side is his predicted

element called eka silicon and so he predicted that the uh atomic mass would be 72 the density

would be 5.5 grams per centimeter cubed the bonding power would be four right and then what he means by the

bonding power is basically how many how many bonds can this element make and he predicted the color would be dark gray

and so all of this was based on the surrounding elements in the periodic table and the pattern that he saw and so

he had predicted this element in 1871 and then in 1886 not long after about 15 years later the element germanium was

discovered and so it was discovered to have an atomic mass of 72.6 a density of 5.47 grams per centimeter cubed which is

basically really close to what he had predicted it has a bonding power of four it can it can make four bonds and it's a

grayish white color so notice here how mendeleev's prediction or predictions were very

accurate when compared to germania's actual characteristics that's amazing so he was able to predict uh these

properties of a missing element based on the periodicity and the patterns in the periodic table

so then now comes along Henry Mosley and Henry Mosley in 1914 rearrange the elements in the periodic table according

to atomic numbers instead of atomic masses and so here uh he determined that the

number of protons is equal to what is called the atomic number and so this uh allows us to have the

periodic table that we have today and so now we see that there are groupings here so if we using this as a

guide we could color code your periodic table to show the three classes so there's this highlighted zigzag normally

in the periodic table that's in yellow and so that usually is a key for dividing the periodic table into two

parts there's actually three major parts or classes of elements that we see here there's this part on the right I'm sorry

on the left the biggest part of the table is on the left of this stairway this yellow highlighted stairway

and then you got the reddish part on the right that's the second part and then you got this green part that's on the

stairway itself and so those are the three parts so we're going to talk about those three

parts in a moment okay so here are the classes so the metals are the light blue so everything

that is light blue are metals and you can see right away that Metals occupy the largest part of the periodic

table about two-thirds of it it seems or three-fourths

and then you have the non-metals the nonmetals are in the red so they're to the right of this stairway and the the

metals are to the left and then you got what are called the metalloids which are the green elements and the metalloid

kind of sounds like something um like if you know what a humanoid is that's something that's human-like right

maybe not quite human but it's got human characteristics and maybe it's got characteristics of other other things

right so a metalloid is something that's metal like it's got characteristics of metals but it also has characteristics

of non-metals too so they're in the middle on this stairway and so let's talk about Metal so Metals

they're on the left of that zigzag line that stairway on the periodic table uh and it's and hydrogen is an exception

a hydrogen is obviously a gas it's not a metal and some chemical properties of metals

is that they have few uh valence electrons so they're all the way to the left of the periodic table so if we're

looking at valence electrons you know those groups 1A and 2A and 3A they those have like three valence electrons

up to most one two and three valence electrons so not a lot of valence electrons for the metals uh they lose

electrons easily right they want to be like a noble gas and so since they have only a few valence electrons it's easy

just to lose those three those valence electrons to become like a noble gas and therefore they will have a positive

charge and that makes them cations some physical properties is that they're malleable malleable means you can beat

it and pound it into shape right ductile means that you can draw it into wires you can pull it so that it thins out in

the wires they're good conductors they're shiny and they are solid at room temperature

so can you guess what metal is not a solid at room temperature if you guessed Mercury you would be

right okay so atoms with few electrons in their outer energy level these are

metals so you could see that in the outermost energy level of beryllium you only have two valence electrons for

sodium you only have one so notice that there's only two in this one and there's only one electron in the

outer one so losing those electrons is no big deal for these these atoms they want to lose those electrons so they

could be like a noble gas so what about no uh non-metals uh so they're to the right of this zigzag line

that highlighted stairway that I pointed to you earlier so some chemical properties these are pretty much the

opposite of metal properties so if you can remember what the metal metallic properties are or the properties of

metals then you just think the opposite so they are instead of being almost empty or have only a few valence

electrons they're almost full right so they have a lot of valence electrons so they're they're like they're like five

six seven and eight right um so they're full or almost full with their valence electrons they tend to

gain electrons and the reason they gain electrons is because gaining electrons makes them more stable because then

they're they can be like a noble gas so gaining electrons makes them more like a noble gas instead of losing electrons

and because they're gaining electrons this gives them a negative charge so they tend to have negative charges and

they make anions so what are the physical properties so again the physical properties are kind

of the opposite of metals right so metals are ductile and malleable and uh non-metals are not ductile or malleable

they're actually you know brittle brittle means that they can break off into pieces pretty easily that you can't

really pound them with the hammer and bend them into shape though they're going to crack and break up into pieces

and you're not going to pull them into wires uh they're bad conductors so metals are

good conductors non-metals are very bad conductors they hardly conduct anything they're mostly solid

although there's a lot of gases as well and maybe a liquid here and uh summer you know gases it

at room temperature okay so here's some examples so we have oxygen fluorine and helium these are all

on the right side of the of that stairway that highlighted stairway on the periodic table

and you'll notice that that fluorine has seven electrons seven valence electrons on its

outer shell so it only needs one electron to be like a noble gas so it's going to pick up that one electron

helium is a noble gas it has a full outer shell with two electrons so that's going to be stable and also notice

oxygen has six valence electrons so it only needs two more to be stable at like a noble gas so it's going to pick up

those electrons pretty easily and so as I said helium is uh full outer shell

oh yeah what about the metalloids they're the green ones that we saw that are smack on the middle so they're along

that stairway so those metalloids have basically uh properties of both metals and non-metals so they're kind of in the

middle as far as their properties go so they border on that zigzag line chemical properties most have half a full uh

Half-Life I'm sorry have a full valence shell so they have half full valence shells most of them do so they're like

in the middle they don't they don't have a little bit they don't have a lot there in the middle and so these guys are

going to make anions or can ions depending on their environment depending on what compound they make so the

physical properties are going to be smack in the middle right so they have properties of metals and nonmetals you

know um so they're very good conductors a lot of uh the the metalloids or what are

also called semi-metals are very [Music] um

they tend to be the semiconductors right so they uh they're in the middle as far as conducting uh and there's no way to

know which properties of each so they have a they have a lot of different properties a mixture of properties

so here uh you'll notice that we have two of these so you have boron and you have a silicon so boron

has three valence electrons and silicon has four so the middle is that's a four is the

half of eight and so these are in the middle they have pretty much half half complete outer energy

level so only have three electrons for the outer energy level and for Boron and

four four silicon so what are the important features of the periodic table so first of all we

need to know we need to we need to use our terminology properly and we we're going to use this very often in science

class in in chemistry you got to know the terminology when we're talking about the periodic table so the first thing

you need to know is that the rows are we don't call them rows they're called periods and they're called periods

because that's where the the periodic repeating pattern occurs it's along the row it's along the period so as you go

from left to right in a period you'll notice that there are certain certain patterns that repeat itself when you go

from one period to the next there's this repeating pattern and so you'll also notice that the uh the elements that are

put together in these columns they have similar characteristics so the similarity of the characteristics as you

go across from left to right repeats when you go down to the next uh period so when you look at lithium

certain characteristics beryllium has certain characteristics boron has certain characteristics carbon and so on

all the way to Neon which is non-reactive and then when you follow from neon which is 10 to sodium you get

the repeating pattern so sodium behaves like lithium magnesium behaves like beryllium aluminum behaves like Boron to

some extent and so on so you get this repeating pattern so the rows are called periods

so each horizontal row of elements is on the periodic table that's called a period

okay so left to right okay

so we have period one only has two elements in it period two has eight elements in it

period three has eight elements in it period four has 18 elements in it so as we're going down these are our periods

so you can see that the periods are numbered on the side on the on the left hand side here

and so we keep going so this would be period five period six now this lanthanide series

here the lanthanides actually fits in between uh the barium and uh the ruthenium here so here it

fits right here in the middle and then same for period seven so the actinides uh this row here fits in

between uh 89 and or I'm sorry 80 88 and 103 so that's where you're going to fit these in so these two rows here fits in

the periods six and seven so they're part of that period as well so how many periods of rows are there on

the periodic table of elements there are seven seven periods so

periodic Properties or period properties so the seven periods they're numbered from the top down numbered from top down

so the first period is on top second third fourth working your way down as we saw in the previous previous slide

so atomic numbers and atomic masses increase as you go from left to right in a period so that's the first thing

masses and atomic numbers increase atomic numbers are going to increase because that's the way the table has

been set up by Mosley so Mosley set it up according to atomic numbers so as we go across period atomic numbers are

going to increase as you go numerically through the periodic table from one element to the next the the the

atomic numbers are increasing so left to right and mass increases as well there are some exceptions where the mass

decreases when you go from one element to the other but I think there's only those two exceptions

so all the elements in the same period have the same number of energy levels that's another thing to keep in mind so

the period number matches the number of energy levels that the atoms in that period have so if you're an element in

Period four then you have four energy levels if you're if you're an element in Period two then you have two energy

levels so all the elements in a period have the same energy levels and that and that number of energy levels is

indicated by the period number so period number one equals one energy level

two equals two energy levels period three has three energy levels and Etc so and what we mean by the

energy levels if we're thinking about the Bohr model with the Solar System model with the nucleus in the center and

the and the electrons traveling around in orbits then each orbit is an energy level and so

um the number of energy levels is going to equal the uh the number period that you're in so

here's some examples of period elements that have the same number of energy levels at in their atoms so you could

see here that they all have uh these two on top they both have two energy levels right these two orbits

each orbit is an energy level so these two elements have two energy levels and then these two on the bottom have

three energy levels so these two elements whichever elements they are we know that they are in Period two because

they have two energy levels the two on the bottom we know that they have to be in Period three whichever elements they

are because they have three energy levels so in what period do you think these

atoms are we just said two period two and the ones on the bottom are going to be in Period three

okay so the other thing you need to know is that the columns these up and down columns are we don't call them columns

we call them groups or families and the reason we call them groups or families is because they have similar

characteristics so just like members of your own family have similar characteristics right maybe the the you

know the children the family have certain physical characteristics maybe they have you know their father's eyes

or maybe they have the mother's hair or colored or whatever the case may be so we share certain characteristics when

you're in a family so because the elements in a group or in a column they share the same kinds of characteristics

we call them families or groups so each column of elements is is considered a group or family in the

periodic table so they go from the top to the bottom or the bottom to the top so this first one would be group one

this is has a special name called The Alkali Metals and then you have group two next to it those are the alkaline

earth metals and then we have these groups throughout the table now these groups starting with

three this gets into what are called the transition elements this is that d block area that we were talking about they're

also called transition elements so we can go through these 10 elements at a time so that's the transition

element and then we got 13. 13 is also called 3A so on the top you can see the numbers of the groups or families

numbered 1 through 18 but we can also call groups one two thirteen fourteen fifteen we can number those 1A 2 a 3A

and so on and so you've got group 14 15 16 17 and 18.

so how many groups or families there are there are 18 groups uh in the periodic table

so what are the properties of these families or groups so there's 18 groups they're numbered from left to right

and the atomic number and masses increase as you go down the group right so going down the group the atoms get

bigger so from the top downward atomic mass is getting bigger atomic numbers are

getting bigger atoms in the same group have the same number of valence electrons so we if we

said this before that if you're in group one especially 1A if we're talking about the

a groupings so if we go back and look at the periodic table here so groups 3 through 12 in this table are

called the transition elements we can ignore those as far as as far as uh valence electrons go so we can label

the other ones starting from left to right we could say this group one is also called 1A and

this group 2 is also called 2A but then we can skip over these middle ones and jump over to 13 and we can call that 3A

and then 14 is 4A 15 is 5A and so on and so those groups those numbers match with the number of valence electrons in your

group so if you're in group 1A you've got one valence electron if you're in group 3A you have three valence

electrons if you're in 5A you've got five analyst electrons 6A you've got six valence electrons and so on

so there are exceptions we talked about uh with the D Block and F block so the group numbers there don't match the

valence electrons the valence electrons are by and large only two so if you have a transition element or an element in

that D and F block uh you're likely to only have one or two valence electrons so groups of elements elements in the

same group have similar physical and chemical properties because they all have the same valence electrons so

remember why do elements react the way they do it goes back to the valence electrons so the number of valence

electrons your atom has dictates the kinds of properties it's going to have so if your elements have the same

valence electrons then they're going to have the same properties that's it for this video I hope you

enjoyed this video I hope this was a learning experience if you like my videos please smash that like button uh

subscribe to my channel hit that notification Bell so you'll be notified by other videos I put out and put

comments in the comment section let me know what you think if you have any questions thanks for joining me have a

great day