AP Chemistry Chapter 7
Atomic Structure and Periodicity
Expected Test Date
Thursday Feb 5th-6th
What is Atomic Structure and
Periodicity?
 Evidence of the atomic structure
 How groups and periods show similar properties
 Most of this has to do with the arrangement of atoms in an
element
Chapter 7.1 Electromagnetic Radiation
 Electromagnetic Radiation: Energy that travels through space
at the speed of light; examples
 Light from sun, energy for microwave, X Rays
 These seem different but they all travel in waves and have
specific wavelengths
 Wavelengths: Distance between two consecutive peaks
between wavelengths
 Symbol λ
Chapter 7.1 Electromagnetic Radiation
 Frequency: Number of wavelengths per second
 Symbol v
 EQUATION TO REMEMBER c = λv
 Given to you on ap exam formula sheet
 c = speed of light which is 2.998X10ms-1
 Speed of light also given to you on AP Chemistry formula sheet
Chapter 7.1 Electromagnetic Radiation
SA Question 1 on Chapter 7 AP Chem
Exam. Book Sample Exercise 7.1
Solution
7.2 Nature of Matter
 All matter emits an electromagnetic radiation. At first this
made scientists think that matter and energy are the same
things however in the early 20th century Max Planck showed
again that energy and matter are the same thing
 Planck determined that energy can be gained or lost only in
whole number multiplies of hv where h is planck’s constant
7.2 Nature of Matter
 Equation to know for nature of matter
 E = nhv
 E is energy, n is an integer, h is Planck’s constant (6.626X10-34 Js), and v
is frequency
SA Question 2 on Chapter 7 AP Chem
Exam. Book Sample Exercise 7.2
Solution
7.11 The Aufbau Principal and the
Periodic Table
 Electron configuration

7.11 The Aufbau Principal and the
Periodic Table
 What is the electron configuration of stromium? Draw a
picture of how electrons move around the nucleus.
7.11 The Aufbau Principal and the
Periodic Table
7.11 The Aufbau Principal and the
Periodic Table
7.11 The Aufbau Principal and the
Periodic Table
7.11 The Aufbau Principal and the
Periodic Table
7.11 The Aufbau Principal and the
Periodic Table
 Aufbau Principle: As protons are added one by one to the
nucleus to build up the elements, electrons are similar added
to these hydrogenlike orbital's.
 Hund’s rule: the lowest energy configuration for an atom is
the one having the maximum number of unpaired electrons.
7.11 The Aufbau Principal and the
Periodic Table
7.11 The Aufbau Principal and the
Periodic Table
7.11 The Aufbau Principal and the
Periodic Table
 Write the long hand and short hand electron configurations
for the following elements…
 Chlorine
 Argon
 Potassium
SA Question 3 on Chapter 7 Test
 Know where the s, d, p, and f block elements are and the
numbers associated with them. Hence be able to label the
periodic table in last slide.
 Be able to identify an element based on the configuration
number
 i.e. 4s2 = Calcium
SA Question 4 on Chapter 7 Test,
sample question 7.7
Soliution
Solution
7.12 Periodic Trends in Atomic
Properties
7.12 Periodic Trends in Atomic
Properties
7.12 Periodic Trends in Atomic
Properties
7.12 Periodic Trends in Atomic
Properties
SA Question 5 on Chapter 7 Test,
sample question 7.9
Solution
7.12 Periodic Trends in Atomic
Properties
7.12 Periodic Trends in Atomic
Properties
 Electron affinity increases upward for the groups and from left to right across periods of
a periodic table because the electrons added to energy levels become closer to the
nucleus, thus a stronger attraction between the nucleus and its electrons. Remember that
greater the distance, the less of an attraction; thus, less energy is released when an
electron is added to the outside orbital. In addition, the more valence electrons an
element has, the more likely it is to gain electrons to form a stable octet. The less valence
electrons an atom has, the least likely it will gain electrons.
 Electron affinity decreases down the groups and from right to left across the periods on
the periodic table because the electrons are placed in a higher energy level far from the
nucleus, thus a decrease from its pull. However, one might think that since the number
of valence electrons increase going down the group, the element should be more stable
and have higher electron affinity. One fails to account for the shielding affect. As one goes
down the period, the shielding effect increases, thus repulsion occurs between the
electrons. This is why the attraction between the electron and the nucleus decreases as
one goes down the group in the periodic table.
7.12 Periodic Trends in Atomic
Properties
7.12 Periodic Trends in Atomic
Properties
SA Question 6 on Chapter 7 Test,
sample question 7.9
Solution
7.13 Properties of a Group: The Alkali
Metals
 Consists of lithium, sodium, potassium, rubidium, cesium,
and francium, Group 1A, group 1, most reactive of all
metals, contain 1 valence electron, as you move down the
group the first ionization energy decreases and the atomic
radius increases which agrees is rules, the ability of the
element to react (reducing agent) increases as you move up a
periodic table, which is typical, hence Cs is the most reactive
and lithium is the least reactive.