1
Chapter 5 Key Terms
Series
Electron Affinity
Period
Noble Gas
Halogen
Sulfide
Oxide
Family
Electronegativity
Ionization Energy
Atomic Radius
Transition Metals
Post-transition Metal
Metalloid
2
Chapter 5
ELEMENTS
3
Periodic Table


Organizes the elements showing similarities and differences
Johann Döbereiner (1829)
 Arranged
elements by atomic mass and noticed groups of elements
with similar properties
 Triads: groups of 3 similar elements
 His work was important step in concept of periodicity of elements

John Newlands (1864)
 Grouped
elements by their increasing atomic masses
 Law of Octaves
 Every
8th element had similar properties
4
Periodic Table

Mendeleev
 Also
arranged elements by their increasing atomic masses
 He
left blanks where he believed undiscovered elements
belonged
 Also

included transition metals
Periodic Law: properties of the elements vary with their atomic
masses in a periodic way
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Periodic Table

Problem – ordering them by atomic mass did not always put
similar elements under each other

Henry Moseley
 Developed
way to count protons in nucleus
 When
atoms were placed in order of amount of protons,
problems went away
 Periodic
Law: properties of an element vary with their atomic
numbers in a periodic way
6
Structure of the Periodic Table

Each block on the periodic table contains certain information
about each element
 Name
of element
 Element

symbol
 Atomic
number
 Atomic
mass
Each periodic table contains other select information

Oxidation states, electron configuration, properties, radioactivity
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Structure of the Periodic Table

Table
 Column:
 Rows:
Family (group) – similar properties
Periods (series) – increasing atomic number
 Metals,
Metalloids, Nonmetals
 Electron
configuration
 Arranged
number
by increasing atomic
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Organization

Metals
 Middle
 Most
act like a metal
 Solid,

and left side
lustrous, malleable, ductile
Metalloids
 Stair-step
line divides these
 Characteristics
 Lustrous,
of metals and nonmetals
brittle, solid
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Organization

Nonmetals
 Far
right side
 Gases,
 Poor

soft solids (exception: Bromine)
conductors
Inner transition metals
 Lanthanide
 Many
& Actinide Series
are radioactive
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Periodic Trends

An atom’s size is dependent on the e- cloud
 Atomic

radius
Atomic Radii decrease from left to right
 Electrostatic
attraction: opposites attract

Atomic Radii increase from top to bottom

Transition metals same size
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Ionic Radii

Cations
 Smaller
 Lost

than regular atom
electron
Anions
 Bigger
 More
than regular atom
repulsion with extra electron
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Ionization Energy

1st ionization energy
 Minimum
electron

Decreases from top to bottom
 Electrons

energy required to remove neutral atom’s outermost/first
farther from nucleus
Increases from left to right
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Electron Affinity

Amount of energy required to add e- to a neutral atom

Measures how strongly an atom attracts additional e-

Decreases from top to bottom

Increases from left to right
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Review

Atomic Radius
 Size

of the atom
Electrostatic Attraction
 Attraction

Ionization Energy
 Energy

between charged particles
needed to remove an electron
Electron Affinity
 Energy
needed to gain an electron
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Electronegativity

Measure of an atom’s ability to attract and hold electrons in a
compound

Increases left to right

Decreases top to bottom
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
The attraction of the electrons to the nucleus affects periodic
trends

In your notes draw 4 boxes labeled:
 Atomic
Radius
 Ionization
 Electron
Energy
Affinity
 Electronegativity

Draw arrows indicating the increasing trend on the chart
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Hydrogen

Simplest and most abundant of all elements

Name means “water-former”

Is a diatomic element

Can act like part of group 1A or 7A

Bonds with many elements to form
important compounds
 Ammonia
(NH3), HCl, H2O, CH4
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Alkali Metals (1A)

So reactive they never exist by themselves in nature

Typically form cations

React violently with water
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Alkaline Earth Metals (2A)

Have 2 valence electrons

Usually form +2 cations
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Transition Metals (B groups)

Typical metal characteristics

Found in trace amounts in body

Many uses
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Inner Transition Metals

Lanthanide Series
 Found

Actinide Series
 Most

in earth’s crust
are manmade and radioactive
Transuranium Elements
 Any
element with an atomic number higher than Uranium has
radioactive isotopes

Paramagnetism
 Any
substance weakly attracted by a magnetic field because of
unpaired electrons
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Post Transition Metals & Metalloids

Post Transition Metals: metals after the transition metals on the
periodic table

Metalloids: semiconductors
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Halogens (VIIA)

“Salt-formers”
 When
they bond with reactive metals

Very reactive

High electronegativity

Cl, Br, I are poisonous gases
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Noble Gases (VIIIA)

Do not readily react with other elements

Not flammable