Transcript The Periodic Table!

The Periodic Table!
Important People to
Remember
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Dmitri Mendeleev
- published 1st periodic table in 1869
- arranged elements by atomic mass
Important People to
Remember
Henry Moseley
- arranged the periodic table for today
- arranged elements by atomic number
Groups and Periods
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On the periodic table:
Elements are arranged according to
similar properties.
Periods
Groups
Copyright © 2008 by Pearson Education, Inc.
Publishing as Benjamin Cummings
Metals, Nonmetals, and
Metalloids
The heavy zigzag line
separates metals and
nonmetals.
• Metals are located to the
left.
• Nonmetals are located to
the right.
• Metalloids are located
along the heavy zigzag
line between the metals
and nonmetals.
Copyright © 2008 by Pearson Education, Inc.
Publishing as Benjamin Cummings
Metals
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To the left of the Zigzag
Malleable (smashed into thin sheets)
Ductile (stretched into wires)
Conduct heat and electricity
Shiny
Reactive
High Melting Points
Mostly Solids at room temperature
- except Hg (liquid)
Examples of Metals
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Fe
Non-Metals
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Right of the zigzag (Upper right side)
Poor conductor of electricity
Dull
Brittle
Low Melting Points
Mostly gases at room temperature
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Liquid (Bromine)
Solids (Sulfur, Phosphorus, Carbon)
Examples of Nonmetals
Sulfur
Carbon
Metalloids
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Along the zigzag line!
Has properties of both metals AND
nonmetals!
Somewhat shiny solids, not much luster
Semiconductive
B, Si, Ge, As, Sb, Te, Po, At
Examples of Metalloids
Silicon
Names of Some
Representative Elements
•
Several groups of representative
elements are known by
common names.
Copyright © 2008 by Pearson Education, Inc.
Publishing as Benjamin Cummings
Alkali Metals
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Group 1: Li, Na, K, Rb, Cs, Fr
VERY reactive
Soft Metals
Rarely exist in nature alone
Form salts when combined
Alkaline Earth Metals
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Group 2: Be, Mg, Ca, Sr, Ba,
Ra
Reactive
Found in compounds that are
in the Earth’s Crust
More dense and harder than
alkali metals
Transition Metals
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In the middle (dblock)
Much LESS reactive
Electron in highest
energy level can
change
Therefore when
they form ions, their
charges can vary.
Examples:
Cu+2
Cu+1
Halogens
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Group 7: F, Cl, Br, I, At
Most reactive non metals
Fluorine most reactive non metal
Physical properties very within group
Noble Gases
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Group 8: He, Ne, Ar, Kr, Xe, Rn
Don’t react or combine with
anyone! (Unless forced) INERT
GASES
Low Boiling Points
All gases at room temperture
Lanthanides
Elements 58-71
- All occur in nature except 61
Rare earth metals
 Very reactive
 High melting points and boiling points
 Used in lamps, lasers, magnets, and
motion picture projectors.
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Actinides
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Elements 90-103
Most are synthetic (man-made)
Almost all are radio active
Very dense
Can be found in smoke detectors,
nuclear weapons, and radio active
minerals
Periodic Law
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Periodic Law = trends that occur
throughout the periodic table
-Atomic Radius
-Ionization Energy
-Electronegativity
How are the elements
organized?
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Atoms in the same group have the
same number of valence electrons.
Outer shell = valence shell (outside
electrons)
8 valence electrons= stable
Valence electrons determine reactivity
and how strongly an atom will bond
with other atoms.
Determine Valence Electrons
- These atoms want 8
valence electrons
- Is it easier for them
to gain or lose a
certain amount of
electrons?
Atomic Radius Trend
What is atomic radius?
- Distance from the nucleus to the valence
electrons
- It’s the size of the atom!
Atomic Radius
-As you go across the period
what happens to the atomic
radius?
-As you go down a group
what happens to the atomic
radius?
Atomic Radius Trend
As you go across a period, the number of protons increases (eincrease too, but on the same energy level). More p+ can pull
in e- closer, decreasing the radius.
More attractions = SMALL atomic
radius
As you go down a group, e- are added to new energy levels. Each level is
further from the nucleus, which increases the radius.
More energy levels = LARGE atomic
radius
Electronegativity
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Electronegativity is the atom’s want to gain
electrons
An atoms LOVE for electrons!!
Electronegativity
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- What happens
when you go
across a period?
- Down a group?
Electronegativity
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As you go across a period, electrons are held more closely because the atomic
radius decreases. It is easier to attract electrons, so electronegativity increases.
Small radius (more attractions) = HIGH
electronegativity
As you move down a group, electrons are further away from nucleus because
the atomic radius increases. It is harder to attract electrons, so
electronegativity decreases.
Large radius (less attractions) = LOW
electronegativity
Electronegativity
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Look at the dot structures!
The atom that wants to GAIN electrons
will have a high electronegativity!
Ionization energy
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Ionization Energy is the energy needed
to remove a valence electron
-What do see as you go
across the period?
-What happens to the
energy going down a
group?
Ionization energy
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•As you go across a period, electrons are held more closely
because the atomic radius decreases. It is easier to attract
electrons, so electronegativity increases.
Small radius (more attractions) = HIGH
ionization energy
As you go down a group, electrons are further from nucleus
because the atomic radius increases. It takes less energy to
remove an electron, so the ionization energy decreases.
Large radius (less attractions) = LOW ionization
energy
You can also look at the dot structures!