Warmup 9/8/15
Elements come in different sizes. Which do you think is
the biggest and why?
Objective
Tonight’s Homework
To determine which element
is the biggest
none
Trends in the Periodic Table
We’ve looked at many things so far, but we
haven’t focused much on the periodic table.
We’re going to review a few things on the table.
The goal here is that you get a bit of
appreciation for just how well-laid out this table
is.
Trends in the Periodic Table
Atomic Size
This trend refers to the size of each atom.
Which is the biggest?
How do we define the edge?
Trends in the Periodic Table
Atomic Size
This trend refers to the size of each atom.
Which is the biggest?
How do we define the edge?
Since electrons pop in and out of existence,
“edge” is a bit hard to define. But we can define
it roughly as the level where the outer electrons
are.
Trends in the Periodic Table
So what kind of sizes are we talking about?
Atoms are in picometers.
1 picometer = 1/1,000,000,000,000 of a meter
Trends in the Periodic Table
So what kind of sizes are we talking about?
Atoms are in picometers.
1 picometer = 1/1,000,000,000,000 of a meter
Smallest atom: Helium – 31 pm
Biggest atom: Cesium – 298 pm
Trends in the Periodic Table
So what kind of sizes are we talking about?
Atoms are in picometers.
1 picometer = 1/1,000,000,000,000 of a meter
Smallest atom: Helium – 31 pm
Biggest atom: Cesium – 298 pm
Add these two to your periodic table. Let’s see if
there’s a trend as well…
Trends in the Periodic Table
Atomic Size
Trends in the Periodic Table
Atomic Size
Larger atomic size to the left and down
Trends in the Periodic Table
Huh. Pretty neat that this follows such a clean
pattern, right?
Let’s see what other patterns there are…
Trends in the Periodic Table
Ionization Energy
This is the amount of energy that it takes to rip
off the outermost electron from the atom.
Remember, each atom wants to fill up its ‘s’ and
‘p’ shells. This means each atom wants 8
electrons in outer shells.
Trends in the Periodic Table
Ionization Energy
This is the amount of energy that it takes to rip
off the outermost electron from the atom.
Remember, each atom wants to fill up its ‘s’ and
‘p’ shells. This means each atom wants 8
electrons in outer shells.
At the top of your table, you wrote the numbers
1 through 8. These show how many electrons
are in the outer shells.
Trends in the Periodic Table
So how much energy does it take to rip off that
outer electron?
Trends in the Periodic Table
So how much energy does it take to rip off that
outer electron?
Lowest: Cesium – 380 kiloJoules / mole
Highest: Helium – 2370 kiloJoules / mole
Trends in the Periodic Table
So how much energy does it take to rip off that
outer electron?
Lowest: Cesium – 380 kiloJoules / mole
Highest: Helium – 2370 kiloJoules / mole
What this means is that for every mole of
Cesium you have, you will have to use 380
kiloJoules of energy to rip the outermost
electron from all of those atoms.
Look at your periodic table. See a pattern
again?
Trends in the Periodic Table
Ionization Energy
Higher Ionization Energy Up and to the Right
Exit Question
Which element is the biggest?
a) Helium
b) Gold
c) Hydrogen
d) Radon
e) Rubidium
f) Cesium