hey there it's Kaeleigh in this lesson we will learn about the periodic table how
it's organized and how to read it let's jump in this is the periodic table of
elements and it's made up of you got it elements each one of the boxes that you
see is a specific element but what is an element elements are often known by
another name you may have learned in one of your lessons atoms you might already
know that atoms are the building blocks of life they are super tiny microscopic
blocks of matter that can't be broken down into any smaller parts since atoms
are so small scientists have decided to make a table to keep track of them all
we're going to learn how this table is organized let's start with the basics
the periodic table is broken up into columns and rows but to be tricky
scientists call them groups and periods groups go down like columns for example
Group one can be found here can you find group 14 yep right here
we keep similar elements in the same group or groups periods go across like
rows for example here is row five can you find row two yep there are a lot of
empty spaces in row two now let's take a look into how the periodic table is
organized the periodic table is mostly made up of elements that are metals in
fact 75% of the table is metals we're going to start with Group one way over
here on the left side but only the yellow boxes period 2 through 7 these
are called the alkali metals
this group is the most reactive group of elements on the table they really react
a lot when they come in contact with water some of the elements can even
explode now let's zoom in on Group two right next to our alkali metals lab our
alkaline earth metals just like alkali metals the alkaline
earth metals live in periods two through seven this is the second most reactive
group of elements on the periodic table they are very unstable and reactive
elements but there are less reactive than the alkali metals now we are going
to look at the biggest set of elements on the table all of these red boxes here
that stretch from group three to group 12 are called the transitional metals
the transitional metals are metals just like the alkali and alkaline earth
metals but the metals in group three to Group twelve hold their electrons
differently than any other elements on the table and that is why they are
called transitional the dark teal boxes are called the post transitional metals
notice that they are grouped to get there after the transitional metals in
groups 13 through 16 and periods 3 through 7 sometimes scientists refer to
the post transition metals as polar metals compared to the transitional
metals the post transition metals are softer and have a lower melting point
meaning they turn to liquid at lower temps let's check out these bottom rows
now first we will take a peek into these pink boxes if we follow the arrow up it
would appear that they technically belong in period 6 these are called
Lanthanides the lanthanides are all metals that are found natural
occurring in the Earth's crust but they are very rare on earth that means that
they're hard to find and there's not a lot of them that exist now if we move
below to the purple boxes we will see that these belong in period 7 we call
this group of elements that actinides the actinides
are found in the very bottom of the periodic table and they also fall into
the metal category but most of them are man-made that means they were created in
a laboratory and cannot be found naturally on earth now what if something
is sort of like a medal but not exactly that's what we call this staircase of
elements in groups 13 through 17 these we call the metalloids metalloids are
not metals but they have a lot of the same properties as metals and there are
seven of them on the periodic table over here in group 17 we have the halogens
they run from periods to to period seven halogens are not metals but they are
reactive especially at the top element as your work weight your way down the
periods they become more stable halogens like to make bonds with elements from
Group one the alkali metals we have another group that we refer to as other
nonmetals since the metalloids and halogens are nonmetals as well but also
have their own specific categories the other nonmetals are found in groups 14
15 and 16 other nonmetals are you guessed it not metals but unlike
metalloids the other nonmetals do not have similar characteristics to metals
and they can exist in all three states of matter at room temperature now we're
going to zoom in here on group 18 periods one through six these are called
the noble gases these noble gases are very stable and hardly ever react what
does it mean for an element to be stable it means the nucleus is tightly held
together with very strong bonds sometimes people refer to them as inert
gases lastly we're going to point out these gray boxes down here these are
called unknown elemental composition and they're all in period seven these
elements in period seven are all made by scientists in the lab and most of them
are metals and very unstable so far they're only used for research to help
scientists understand how atoms work now what does it look like if we zoom in on
just one element what do all those symbols mean this is a super zoom on an
element box for helium helium is a noble gas so it goes in group 18 of the
periodic table we can tell that this is helium because the element name can be
found down here at the bottom but sometimes it's handy to have a short
name for the elements that is what these big letters in the element box are we
call it the element symbol for helium it's h e up in the left corner is the
atomic number it is called the atomic number because it represents how many
protons are in the elements atom how many protons says helium have two and up
here in the right corner we have the atomic mass the atomic mass is that an
average mass for each atom in any form that it takes well look at you now when
you look at this picture you can identify each group on the periodic
table and decode the boxes for each element
great job now practice what you know by playing our online games and doing the
online quizzes and remember to always be clever