This document provides an overview of the periodic table and periodic trends. It begins with the history and development of the modern periodic table. It then discusses the organization of the periodic table into groups and periods. Several periodic trends are explained, including how atomic mass, atomic radius, electronegativity, ionization energy, and electron affinity change across periods and down groups. Reasoning for these trends is given based on electron shielding and distance from the nucleus. Ionic charge and radii are also covered. The document aims to teach the key aspects of the periodic table and periodicity in chemistry.

1. High School Chemistry Rapid Learning Series - 14
Rapid Learning Center
Chemistry :: Biology :: Physics :: Math
Rapid Learning Center Presents …
p
g
Teach Yourself
High School Chemistry in 24 Hours
1/52
http://www.RapidLearningCenter.com
The Periodic Table and
Chemical Periodicity
HS Ch i t R id Learning Series
Chemistry Rapid L
i
S i
Wayne Huang, PhD
Kelly Deters, PhD
Russell Dahl, PhD
Elizabeth James, PhD
Rapid Learning Center
www.RapidLearningCenter.com/
© Rapid Learning Inc. All rights reserved.
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
1

2. High School Chemistry Rapid Learning Series - 14
Learning Objectives
By completing this tutorial you will learn…
The organization of the
periodic table.
table
How properties of an
element can be
determined from trends of
the periodic table.
How electronegativity,
ionization energy electron
energy,
affinity relate to atomic
radii.
How ionic radii relates to
atomic radii.
3/52
Concept Map
Previous content
Chemistry
New content
Studies
Matter
One type of is
Periodic
Table
Organized on
Elements
Atomic
Mass
Used to predict properties of elements according to trends
Atomic
Radii
Electronegativity
Ionization
Energy
Electron
Affinity
Ion Charge
& Radii
4/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
2

3. High School Chemistry Rapid Learning Series - 14
History of the
Periodic Table
5/52
Development of the Modern Table
Scientists went through many revisions to
arrive at the current Periodic Table.
Many scientists
organized the elements
in different ways.
Mendeleev organized the
elements by atomic
mass in rows/columns
g
p p
according to properties.
Some holes were left if no
known element had the
properties needed to fit
p
the pattern.
More elements were
discovered.
6/52
These systems had
various flaws.
The holes were filled in.
Elements were reorganized by atomic
number.
A couple of elements
switched places.
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
3

4. High School Chemistry Rapid Learning Series - 14
Organization of
the Periodic Table
of Elements
7/52
Definition: Periodic Table
Periodic Table – A tool used
by chemists. It organizes the
elements and provides
information about them.
Elements are organized by
increasing order of atomic
number (Z).
The atomic number is the
number of protons and
determines the identity of the
atom.
8/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
4

5. High School Chemistry Rapid Learning Series - 14
Groups and Periods
The periodic table is organized by:
Periods
Rows are called
“periods”
Groups
Columns are called
“groups” or “families”
groups
families
9/52
Information for Each Element
Most periodic tables give the following information,
but it can be in a different location.
Element Symbol
If there’s a second
letter, it’s lowercase.
Atomic Mass
Number with decimals.
Give the mass for 1 mole
of atoms.
6
C
Carbon
C b
12.01
Atomic Number
Whole
Wh l number—
b
elements are ordered
by this on the
periodic table.
Element Name
El
tN
10/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
5

6. High School Chemistry Rapid Learning Series - 14
Metals and Non-Metals
The stair-step separates the metals & non-metals.
Metalloids touch the stair-step.
Most active
non-metals
Most active
metals
11/52
Properties of Metals and Non-Metals
There are several characteristics of each type of
element:
Metals
High electrical
conductivity
Low electrical
conductivity
High melting
points
Low melting
points
Malleable &
ductile
12/52
Non-Metals
Brittle
Bi l
Gold (Au)
Graphite (C)
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
Metalloids
Have
properties of
both metals
and nonmetals.
Silicon (Si)
6

7. High School Chemistry Rapid Learning Series - 14
How to Memorize
the Elements 1-20
13/52
Mnemonic for the First 20 Elements
Happy H
H
Henry, Th Li l B
The Little Beach B
h Boy, C N dO FiN
CaN
FiNe;
Naughty Megan, the Alpine
Sister, Pretends to Ski at ClArK Canyon
14/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
7

8. High School Chemistry Rapid Learning Series - 14
Periodicity
15/52
Definition: Periodicity
Periodicity of the Periodic Table – The
predictable pattern by which properties of
elements change across or down the
l
t h
d
th
periodic table.
There are always exceptions
to these periodicity trends…
each of the trends is a
“general” trend as you move
across a period or down a
group.
16/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
8

9. High School Chemistry Rapid Learning Series - 14
Atomic Mass
17/52
Definition: Atomic Mass
Atomic Mass – the mass in grams for 6.02 ×
1023 atoms, i.e. the mass of one mole of
atoms, found on the periodic table.
,
p
Atomic Mass = Abundance-weighted average
of all of its element’s isotopes.
Atomic Mass vs Mass Number
Atomic Mass – Average mass
of an atom (a decimal
number).
i.e. Pt = 195.1 amu
Mass Number – Sum of
#protons and neutrons (a
whole number).
i.e. Pt = 78 + 117 = 195
18/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
9

10. High School Chemistry Rapid Learning Series - 14
Atomic Mass Trends
In general, the atomic mass:
Increases
Increases
19/52
Atomic Mass Trends Reasoning
Why does atomic mass increase across a period?
• Moving left to right, the number of protons, neutrons
and electrons all increase.
• M
More subatomic particles l d t higher mass.
b t i
ti l lead to hi h
Why does atomic mass increase down a group?
For the same reason as above!
e
e
n
p
n p
n p
e
Move across the
periodic table
Mass increases
Lithium atom
e
e
pn
p p
nn p
n
e
e
Beryllium atom
20/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
10

11. High School Chemistry Rapid Learning Series - 14
Atomic Radii
21/52
Definition: Atomic Radius
Atomic Radius – Half of the distance
between the nuclei of two bonded atoms
b t
th
l i ft
b d d t
(the measure of the size of its atom).
H
H
Distance between nuclei (d)
Atomic radius of hydrogen atom
(r = d/2)
22/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
11

12. High School Chemistry Rapid Learning Series - 14
Atomic Radii Trends
In general, atomic radii:
Decreases
Increases
Max
23/52
Memory Tip: For its trend, just memorize the maximum value position (Max).
Atomic Radii Trends Reasoning, Part 1
Why does atomic radii decrease across a period?
Moving left to right, the number of protons, neutrons and
electrons all increase.
e
e
e
n
p
n p
n p
e
Move across the
periodic table
Radius decreases
Lithium atom
e
e
pn
p p
p
n
n n
e
Beryllium atom
As the # of protons and electrons increase, the attraction
between the positive nucleus and negative electron cloud
increases.
This attraction “pulls” in on the electrons – “Electron Shielding”.
24/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
12

13. High School Chemistry Rapid Learning Series - 14
Atomic Radii Trends Reasoning, Part 2
Why does atomic radii increase down a group?
Protons, neutrons and electrons are also added as you
move down a group.
e
e
Move down the
periodic table
e
+
e
e
Radius increases
e
e
e
e
e
+
e
e
e
e
Lithium atom
Sodium atom
However, the electrons are added in new energy levels.
25/52
The inner electrons “shield” the new outer electrons from the
pull of the nucleus, therefore it doesn’t pull in like the last slide.
Electronegativity
26/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
13

14. High School Chemistry Rapid Learning Series - 14
Definition: Electronegativity
Electronegativity (EN)
– Th pull a nuclear has on
The
ll
l
h
the electrons it shares in a
bond with another atom
(i.e. A measure of the
attraction of an atom for
electrons in a covalent
bond).
27/52
Electronegativity Trends
In general, electronegativity:
Increases
Max
Decreases
28/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
14

15. High School Chemistry Rapid Learning Series - 14
Electronegativity Trends Reasoning - 1
Why does electronegativity increase across a
period?
Moving left to right, the radius of the atom decreases as
more protons pull on more electrons.
Move across the
periodic table
e
e
n
p
n p
n p
e
e
e
pn
p p
p
n
n n
Radius decreases
e
Electronegativity increases
Lithium atom
e
Beryllium atom
When an atom is smaller, the electrons are closer to the
nucleus, and therefore feel the pull more strongly.
Smaller atoms will have a higher electronegativity.
29/52
Electronegativity Trends Reasoning - 2
Why does electronegativity decrease down a
group?
As you move down a group, the radius increases as more
electrons shells are added
added.
e
e
e
+
Move down the
periodic table
e
e
e
e
e
e
Electronegativity decreases
e
+
Radius increases
e
e
e
e
Lithium atom
Sodium atom
As the outer electrons (those involved in bonding) are farther
from the nucleus, they will feel the “pull” of the nucleus less.
30/52
Larger atoms have lower electronegativity.
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
15

16. High School Chemistry Rapid Learning Series - 14
Ionization Energy
31/52
Definition: Ionization Energy
Ionization energy (IE) –
The energy needed to pull
off the furthest out
electron.
(i.e. First ionization
energy: X
X+ + e-)
).
Outmost electron
32/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
16

17. High School Chemistry Rapid Learning Series - 14
Ionization Energy Trends
In general, Ionization Energy:
Increases
Max
Decreases
33/52
Ionization Energy Trends Reasoning - 1
Why does Ionization Energy increase across a
period?
Moving left to right, the radius of the atom decreases as
more protons pull on more electrons.
Move across the
periodic table
e
e
n
p
n p
n p
e
e
e
Radius decreases
IE increases
Lithium atom
e
pn
p p
p
n
n n
e
Beryllium atom
When an atom is smaller, the electrons are closer to the
nucleus, and therefore feel the pull more strongly.
It is harder to pull electrons away from these smaller atoms.
34/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
17

18. High School Chemistry Rapid Learning Series - 14
Electronegativity Trends Reasoning - 2
Why does electronegativity decrease down a
group?
As you move down a group, the radius increases as more
electrons shells are added
added.
e
e
Move down the
periodic table
e
+
Radius increases
IE decreases
e
e
e
e
e
e
e
+
e
e
e
e
Lithium atom
35/52
Sodium atom
As the outer electrons (those involved in bonding) are farther
from the nucleus, they will feel the “pull” of the nucleus less.
It is easier to remove an electron from a larger atom.
Electron Affinity
36/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
18

19. High School Chemistry Rapid Learning Series - 14
Definition: Electron Affinity
Electron Affinity (EA) –
The amount of energy
released when an
electron is added to an
atom.
i.e.
i X + eX-
eEA
Outmost electron
37/52
Electron Affinity Trends
In general, electron affinity:
Increases
Max
Decreases
38/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
19

20. High School Chemistry Rapid Learning Series - 14
Electron Affinity Trends Reasoning - 1
Why does Electron Affinity increase across a
period?
Moving left to right, the radius of the atom decreases as
more protons pull on more electrons.
Move across the
periodic table
e
e
n
p
n p
n p
e
e
e
pn
p p
p
n
n n
Radius decreases
e
EA increases
Lithium atom
e
Beryllium atom
When an atom is smaller, the electrons are closer to the
nucleus, and therefore feel the pull more strongly.
39/52
A smaller atom can handle an extra electron more easily as it
can be more “controlled” by the closer nucleus.
Electron Affinity Trends Reasoning - 2
Why does electron affinity decrease down a group?
As you move down a group, the radius increases as more
electrons shells are added.
e
e
e
+
Move down the
periodic table
e
e
e
e
e
e
EA decreases
e
+
Radius increases
e
e
e
e
Lithium atom
Sodium atom
As the outer electrons (those involved in bonding) are farther
from the nucleus, they will feel the “pull” of the nucleus less.
40/52
The larger atom is less able to “control” a new electron added.
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
20

21. High School Chemistry Rapid Learning Series - 14
Ionic Charge & Radii
41/52
Definition: Ion
Ion – Atom (or group of atoms) with a charge
(i.e. Cl-, NH4+).
Cation – Positively charged ion
(i.e. Na+, Fe3+). Results from loss
of electrons (i.e. Na
Na+ + e-).
Anion – Negatively charged ion
(i.e. F-, HSO4-). Results from gain
of electrons (i.e. F2 + 2e- 2F-).
Mnemonic: Cation = Ca+ion (letter “t” appears like
“+”, hence a positive ion; ANION = A Negative ION.
42/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
21

22. High School Chemistry Rapid Learning Series - 14
Predicting Ion Charge
Some ion charges can be determined from the
element’s placement on the periodic table.
Periodic Table - Charges of Common Ions
H+
Li + Be 2+
N3-
Na + Mg2+
K+ Ca 2+
F-
P3-
Al3+
O2S2-
Cl -
Zn2+ Ga 3+
Rb+ Sr2+
Se 2- Br-
Ag+ Cd2+
I-
Cs+ Ba 2+
Fr+ Ra 2+
43/52
Note: Elements with multiple charges are called multivalent, such
as many transition metals, i.e. Cu(I) and Cu(II).
Ionic Radii - Cations
How does the radius of a cation compare to the
parent atom?
Atoms lose electrons to create positive ions.
e
e
e
+
Creating a cation,
losing electrons
Radius decreases
Lithium atom
e
e
+
Li+ ion
When electrons are lost, there are now more protons than
electrons.
44/52
Therefore, the protons have a greater “pull” on each of the
electrons.
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
22

23. High School Chemistry Rapid Learning Series - 14
Ionic Radii - Anions
How does the radius of an anion compare to the
parent atom?
Atoms gain electrons to create negative ions.
e
e
e
e
e
+
e
e
Creating an anion,
gaining electrons
e
e
e
+
Radius increases
e
e
e
e
e
e
e
Oxygen atom
e
O2- ion
When electrons are gained, there are now more electrons than
protons.
45/52
Therefore, the protons have a weaker “pull” on each of the
electrons.
Trend
Summary and
Examples
46/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
23

24. High School Chemistry Rapid Learning Series - 14
Summary of Trends
In general:
Atomic Mass: Increases
Atomic Radii: Decreases
Electronegativity: Increases
Ionization Energy: Increases
Electron Affinity: Increases
Periodic Trend Mnemonic:
Atomic Mass: Increases
Atomic Radii: Increases
Electronegativity: Decreases
Ionization Energy: Decreases
Electron Affinity: Decreases
(Word beginning with “E”)
Max: EN, IE & EA
Max: Mass, Radii (No “E”)
47/52
Trend Mnemonic: “E” word containing properties (EN, IE and EA) have their max
value on the upper right corner of the periodic table and Non-”E” word containing
properties (Atomic Mass and Atomic Radii) have their max value at the lower left.
Example #1
Example:
List Li, Cs and K in increasing order of:
These elements are in the same group.
A: Atomic radii
Li < K < Cs
Size of the atom
As you move down a group, electron shells are added.
This makes a larger atom.
The element at the top will be the smallest.
B: Electronegativity Pull an atom has on electrons it shares in a bond.
Cs < K < Li
As you move down a group, atoms get larger.
The larger the atom, the less pull on the electrons.
Smallest atom will have the highest electronegativity.
C: Ionization Energy Energy needed to remove the outermost electron.
electron
Cs < K < Li
D: Electron Affinity
Cs < K < Li
48/52
As you move down a group, atoms get larger.
The larger the atom, the less pull on the electrons.
Smallest atom will have the highest ionization energy.
Energy released when another electron is added.
As you move down a group, atoms get larger.
The larger the atom, the less pull on the electrons.
Smallest atom will have the highest electron affinity.
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
24

25. High School Chemistry Rapid Learning Series - 14
Example #2
Example:
Put in order of increasing size: Ca, Ca2+ and Ca+.
Ionic Radii:
Cations are formed by removing electrons
electrons.
When electrons are removed, there are more protons per electron.
The pull on each electron from the nucleus is now greater.
The cation will be smaller than the parent atom.
Ca2+ < Ca+ < Ca
49/52
Learning Summary
Other periodic trends
(Electronegativity,
Ionization Energy
and Electron Affinity)
can be reasoned
through using the
atomic radii trend.
The periodic
table
t bl organizes
i
the elements by
atomic number.
The periodic table can
be used to determine
chemical properties of
an element based on
periodic trends.
Ions gain or lose
electrons to form a
g
charge. Cations
are smaller and
anions are larger
than the “parent”
atom.
Radii decreases across
the periodic table and
increases down the
periodic table.
50/52
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
25

26. High School Chemistry Rapid Learning Series - 14
Congratulations
You have successfully completed
the tutorial
Periodic Table and
Chemical Periodicity
y
Rapid Learning Center
Rapid Learning Center
Chemistry :: Biology :: Physics :: Math
What’s N t
Wh t’ Next …
Step 1: Concepts – Core Tutorial (Just Completed)
Step 2: Practice – Interactive Problem Drill
Step 3: Recap – Super Review Cheat Sheet
Go for it!
52/52
http://www.RapidLearningCenter.com
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com
26