AP Chemistry Chapter 7
Atomic Structure and Periodicity
Expected Test Date
Thursday Feb 5th-6th
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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
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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
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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
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Chapter 7.1 Electromagnetic Radiation
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SA Question 1 on Chapter 7 AP Chem
Exam. Book Sample Exercise 7.1
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Solution
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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
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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
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SA Question 2 on Chapter 7 AP Chem
Exam. Book Sample Exercise 7.2
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Solution
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7.11 The Aufbau Principal and the
Periodic Table
 Electron configuration

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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.
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7.11 The Aufbau Principal and the
Periodic Table
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7.11 The Aufbau Principal and the
Periodic Table
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7.11 The Aufbau Principal and the
Periodic Table
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7.11 The Aufbau Principal and the
Periodic Table
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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.
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7.11 The Aufbau Principal and the
Periodic Table
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7.11 The Aufbau Principal and the
Periodic Table
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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
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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
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SA Question 4 on Chapter 7 Test,
sample question 7.7
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Solution
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Solution
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7.12 Periodic Trends
 Valance electrons = Roman number = s + p number
All atoms are unstable until they have 8 valence electrons (same
as noble gasses)
1. Answer these questions about the atoms.
a. What is the s or the s + p orbitals for the following?
b. How many valance electrons does it have?
 Li =
 Ne =
 I=
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7.12 - Atomic Radius
 Atomic radius is approximately the distance from the nucleus
of an atom to the outside of the electron cloud where the
valence electrons are found. The reactivity of the atom
depends on how easily the valence electrons can be removed,
and that depends on their distance from the attractive force
of nucleus. Since protons and electrons are attracted to each
other the size of the radius changes based on how many
protons there are. Also whenever an s orbital is added the
atomic radius increases.
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7.12 Atomic Radius
 Think of it like this: Across a period, protons increase. Down
a group, s orbitals increase
 So as you move from left to right across a period, the atomic
size? __________

Why?
 So as you move down a group the atomic size? _________

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Why?
7.12 Ionization energy
 Ionization energy is the energy needed to overcome the
attraction between the positive charge of the nucleus and the
negative charges of the electrons and remove electrons from
an atom. Think of ionization energy as how strongly an
atom’s nucleus holds onto its valence electrons(outermost
electrons). A high ionization energy value indicates that an
atom has a strong hold on its valence electrons and is less
likely to lose its electrons. A low ionization energy indicates
that an atom has a weak hold on its valence electrons and is
likely to lose one or more electrons.
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7.12 Ionization energy
 Think of it like this: If an atoms want to lose an electron it
has a low ionization energy. Also if this electrons are far away
from protons, it is easier to lose it.
 So as you move from left to right across a period, the
ionization energy? __________

Why?
 So as you move down a group the
ionization energy? _________

Why?
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7.12 Electronegativity
 The electronegativity of an element indicates the relative
ability of its atoms to attract electrons in a chemical bond.
Keep in mind all atoms want 8 total valance electrons. These
values are calculated on a number of factors and are
expressed in terms of a numerical value of 4.0 or less. The
units used to express electronegativities are called Paulings.
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7.12 Electronegativity
 Think of it like this: Atoms that want electrons will have a
higher electronegativity
 So as you move from left to right across a period, the
electronegativity? __________
Why?
 So as you move down a group the
electronegativity? _________
Why?
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7.12 Electron Affinity
 The electron affinity of an element is the energy given off
when a neutral atom in the gas phase gains an extra electron
to form a negatively charged ion. A fluorine atom in the gas
phase, for example, gives off energy when it gains an electron
to form a fluoride ion.
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7.12 Electron Affinity
 Think of it like this: An atom wants to lose an electron then it
will release more energy.
 So as you move from left to right across a period, the
electronegativity? __________
Why?
 So as you move down a group the electronegativity energy?
_________
Why?
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