Transcript Periodic Table - Mrs. Sousa`s Science Site

Periodic Table
The Basics
Chemistry
Mrs. Sousa & Mr. Pickin
4/13/2015
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Introduction
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This presentation will give you all
the information you need to know
about the basic organization of the
periodic table
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Origin
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The periodic table was first devised
by Dmitiri Mendeleev in Russia in
1869
Based on the “Periodic Law”
which states that the properties of
the elements repeat periodically
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Basics
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Elements listed by increasing atomic number
(Unique for each element) (thus properties)
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Atomic number is the number of protons
contained in the nucleus of an atom of an
element
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Major Divisions in Table
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Metals (<4 valence electrons)
form + ions (cations). Ionic bonds
Non-metals (>4 valence electrons)
form - ions (anions). Covalent bonds
Metalloids (semi-metals)
Separated by zig-zag line
Image
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Periods
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Horizontal (across) rows are called periods.
Properties of elements change across the
period.
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7 periods (maximum)
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Period number is the number of energy
levels each element contains in that row
(quantum # n value as well)
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Groups/Families
Either term acceptable
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Vertical columns 18 families
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Numbered from left to right
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Members of the same family have very
similar chemical and physical properties.
Atoms increase in size as you get lower in a
group.
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Representative Families.
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Representative families are 1,2,13,
14,15,16,17,18
Ones place is the number of valence electrons
In other words- for 13-18 put your finger over the #1!
Ex. Family 16 has 6 valence electrons
Valence electrons are those in the outer energy level –
they are used for bonding and come from the s & p orbital
space
Noble Gases (group #18) all have 8 valence electrons.
Exception to the octet rule: He (helium) has 2 valence
electrons
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Common Names
 1-Alkali metals (most active metals)
 2-Alkaline earth metals
 16-Chalcogens
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17-Halogens (most active non-metals)
18- Noble gases (not reactive)
3-12 Transition metals (1 or 2 valence
electrons)
Lanthanide series (AN 57-71)
Actinide series (AN 89-103)
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Regions of the Periodic Table
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Group 1: Alkali Metals
Reaction of
potassium + H2O
Cutting sodium metal
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Group 2: Alkaline Earth Metals
Magnesium
Magnesium
oxide
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Group 17: The
Halogens (salt
makers)
F, Cl, Br, I, At
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Group 18: The Noble (Inert)
Gases
He, Ne, Ar, Kr, Xe, Rn
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Lighter than air
balloons
“Neon” signs
Very Unreactive
because they have
full electron levels
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XeOF4
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Transition Metals (elements)
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Families 3-12
Lanthanide series click
Actinide series
Multivalent – can have 1, 2, 3 valence
electrons – depending on what other
atoms they are bonding with.
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Transition
Elements
Lanthanides and actinides
Iron in air gives
iron(III) oxide
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s, p, d, f blocks
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Atomic Radius (size)
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The trend is that:
•Atoms get smaller going across a period
(Noble gases are the exception)
•Atoms get larger going down a family
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Atomic Radius (cont.)
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Atomic Radius (cont)
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Ionization Energy (IE)
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The amount of energy necessary to remove
one or more electrons from an atom in its
gaseous state
Generally:
Metals have low IE
 Non-metals have high IE
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Ionization Energy (IE)
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IE increases across a period
IE decreases down a family
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Electronegativity (EN)
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The tendency of an atom to attract electrons (affinity for
electrons)
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An atom's electronegativity is affected by both the positive
charge in the nucleus and the distance that its valence
electrons reside from the charged nucleus.
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The higher the associated electronegativity number, the
more an element or compound attracts electrons towards it.
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Range of EN’s for the elements is 0.7 (Fr) to 4.0 (F)
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Trend:
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EN increases across a period and decreases
down a family
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Electronegativity (EN) Trend
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Electronegativity (cont.)
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Electron Affinity
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The energy released when an electron is
added to a neutral atom. (exothermic
process) for the first added electron the
process is exothermic
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