In a video store, the latest movies are usually placed on the shelves in alphabetical order. Older movies are grouped into categories such as Action or Comedy. The manager has to choose a set of categories and then place each movie in the most

1
In a video store, the latest movies are usually
placed on the shelves in alphabetical order.
Older movies are grouped into categories such as
Action or Comedy. The manager has to choose a set
of categories and then place each movie in the
most appropriate location.
2
Scientists faced a similar challenge when they
looked for a logical way to organize the
elements.
3
Mendeleev arranged the elements into rows in
order of increasing mass (not atomic ) so that
elements with similar properties were in the same
column.
4
There was a hole in this table a missing element
that had not been discovered at the time.
Mendeleev predicted the properties of a missing
element in his table. He said that eka-aluminum
would be a soft metal with a low melting point
and a density of 5.9 g/cm3.
5
Gallium is a soft metal with a melting point of
29.7C and a density of 5.91 g/cm3.
6
The close match between Mendeleev's predictions
and the actual properties of new elements showed
how useful his periodic table could be.
7
In the modern periodic table, elements are
arranged by increasing atomic number (number of
protons).
8
periodic lawthe pattern of repeating properties
displayed by elements in the periodic table
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Groups are verticaland have similar
propertiesGroup 1 H through FrPeriods are
horizontalPeriod 2 Li through Ne
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Elements are classified as metals, nonmetals, and
metalloids
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Metals are elements that are good conductors of
electric current and heat. Most metals are
malleable, they do not shatter when hit. Many
metals are ductile that is, they can be drawn
into thin wires.
12
Nonmetals are elements that are poor conductors
of heat and electric current. All the gases in
the periodic table are nonmetals. The nonmetals
that are solids at room temperature tend to be
brittle. If they are hit with a hammer, they
shatter or crumble.
13
Metalloids are elements with properties that fall
between those of metals and nonmetals. For
example, metals are good conductors of electric
current and nonmetals are poor conductors of
electric current.
14
The elements in Group 1 are called alkali metals.
These metals have s1 electrons and are extremely
reactive(Group 2-alkaline earth metals,
Group17-Halogens, p.162)
15
Group18 noble gases. Helium s2all others are
stables2p6
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s, p, d, f blocks
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Electronegativity how much the nucleus wants
the electronAtomic radii decreases as
electronegativity increases.
18
Ions- have lost or gained electrons

• Would something with a high electronegativity
  want to lose or gain electrons?

19
Sketch a table, and leave some space
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Periodic Trends
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First ionization energy energy needed to remove
1 electron
23
Which would take more energy to remove an
electron from?

• Fluorine or Oxygen

24
Electrons have a negative charge

• How does the charge of an atom change if the atom
  gains an electron?
• How does the charge of an atom change if the atom
  loses an electron?

25
Atom vs Common Ion Radii p 178
26

• Ions with positive charges are smaller than atoms
  (lost electrons)
• Ions with negative charges are larger than atoms
  (gained electrons)