# Periodic Table and Its Trends - PowerPoint - PowerPoint

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```							Periodic Table and Its Trends
2A.6 – A.8, and A.10
Characteristics of Elements

atomic #
19

K
Potassium
element symbol

element name

atomic mass
39.098
Atomic Number
 The number
of PROTONS
in the
nucleus of
the atom of
that
ELEMENT.
Nucleus
 The nucleus of an Atom
is composed of
PROTONS & NEUTRONS.
 Positive Charge
 Occupies a very small
portion of the volume of
the atom.
 VERY   HIGH DENSITY
Atomic Mass Number
 Most  of the MASS
is concentrated in
it’s nucleus.
 Therefore, the
total number of
protons and
neutrons is the
MASS NUMBER.
Isotopes
 Atoms that have the same
number of PROTONS but different
numbers of NEUTRONS
 They are however chemically
alike, because they have the
same numbers of PROTONS and
ELECTRONS
 These subatomic particles
(protons and electrons) are
responsible for the elements
behavior.
Isotopic Notation
• There are two ways to represent elements:
• Symbol Form:
mass number         #
atomic #
(# of   p +)
#   X    element
symbol

OR    mass number   #
X   element
symbol
• Shorthand Form:
name of element followed by atomic mass
number.     • Ex... Aluminum - 27
Nitrogen - 14
Carbon - 14
• You can find mass #, atomic #, # of n0, and #
of e- with either notation!
Average Atomic Mass
 Is the weighted average of the
isotopes of that element. The
weighted average reflects both
the mass and the relative
abundance of the isotopes as they
occur in nature.
 This is why there are decimals in
the average atomic mass i. e.
molar mass.
PERIODIC LAW
When the elements are
arranged in order of
increasing atomic #: there
is a periodic repetition of
their physical and chemical
properties
PERIODIC TABLE
A  column of elements =
GROUP
 Arranged according to
SIMILARITIES in their
properties
 A row of elements =
PERIOD
Columns (Vertical)

   Called Groups or Families
   Eight main Columns
   Elements within a Family are
similar but not identical in
properties
– Same # of valence electrons
– All similar in chemical reactivity
– All similar in physical appearance
Rows (Horizontal)

 Also called Periods
 Determines the # of energy
levels
 Elements in a period – not alike
in properties but pattern exists.
 First elements in a Period –
VERY ACTIVE SOLIDS
 Last element in a Period –
Always very Inactive Gas
FAMILIES
 ALKALI      METALS
– Group I – 1 valence electron +1
– Most Active metals
– Ex. Lithium, Sodium, Potassium
– Soft, shiny metals low melting points, good
conductors of heat and electricity
– React vigorously with water
– React rapidly with O2
ALKALINE EARTH
METALS
–Group II – 2 valence
electrons +2
–Second most reactive metals
–Examples: Beryllium,
Magnesium, Calcium
–Gray-White luster, Harder than
alkali metals
–Less reactive; Reacts with air
Rare-Earth Elements
–So similar that they belong in
same square of periodic table
–Lanthanide Series
Soft,malleable metals
High luster & conductivity

–Actinide Series

Allare synthesized except for
three elements.
Noble Gases (Inert)

–Group VIII A
–Outermost energy level
is full.
–Stable: Non-Reactive
–Ex: Helium, Neon,
Argon, Krypton, Xenon,
FAMILIES
 Halogen        Family
– Group VII A
– 7 valence electrons
   (-1) charge
– Most reactive of non-metals
– React with metals to form SALTS
– Example: Fluorine: most reactive of
halogens, Chlorine, Bromine, Iodine
Transition Metals
–Properties similar to one
another, but do not fit any
other family
–Less active than alkali or
alkaline earth metals
–Form compounds that are
brightly colored
–Example: Iron, Cobalt,
Nickel, Copper, Gold, Silver
FAMILIES
 Boron   Family
–Group III A
–(+3) charge
 Carbon   Family
–Group IV A
–(-4) or (+4) charge
 Nitrogen   Family
–Group VA
–(-3) charge
Oxygen Family
–Group VI A
–(-2) charge
–Contains non-metals O
and S
–Contains metalloids:
Selenium, Tellurium
–Contains metal: Polonium
The Periodic Table
Part II—Periodic Trends
Unit 2A.9
The Periodic Law

When elements are arranged in
order of increasing atomic
number, there is a repeating
pattern of their chemical and
physical properties
Example of The Periodic
Law
Periodic Trends

• Electronegativity

•Shielding Effect

•Ionization Energy

•Metallic vs. Non-metallic
Character
Periodic Table Trends
•   Atomic Radii: one-half of the distance
between the nuclei of two like atoms in a
diatomic molecule
•   Increases as you move down a group
•   Outer e- are farther from the nucleus as you go
down the group; more energy levels
•   Decreases as you move across a period (left
--> right)
•   Increase in nuclear charge while shielding
effect remains constant
Periodic Table Trends
•   Electronegativity: the ability of an atom to
attract electrons to itself when chemically
combined with atoms of other elements
•   Electronegativity values have been calculated
(Pauling electronegative scale) F = 4.0, Cs = 0.7

•   Decreases as you move down a group
•   Increases as you move across a period (left -
-> right)
Periodic Table Trends

   Shielding effect- the decrease in
attraction between an electron and the
nucleus in any atom with more than
one electron shell
   Increases as you move down a group
   Remains the same as you move across
a period
Periodic Table Trends

   Ionization Energy- the energy
necessary to remove an electron from
the outermost orbital of a neutral
atom
   Decreases as you move down a group
   Increases as you move across a period
Periodic Table Trends
•   Metallic Character: the ability of an atom
to loose electrons
•   Increases as you move down a group
•   Decreases as you move across a period (left --
> right)

•   Non-metallic Character: the ability of an
atom to gain electrons
•   Decreases as you move down a group
•   Increases as you move across a period (left -->
right)
2A.1 – A.2
&
2A.4
Aproperty that can be observed or
measured without changing the identity of
the sample of matter.
– Color, size, shape, density, odor, ductility,
malleability, luster, melting point, boiling
point, state of matter, etc.
A change in matter in which the identity
of the material involved does not change
– The material remains the same, although its
form appears to have changed
– Melting, boiling, bending, etc.
Aproperty that can only be observed or
measured by changing the identity of the
sample of matter.
– Chemical reactivity
Asubstance changes into one or more
new substances
– A chemical reaction takes place
– Burning or rusting
– Can often be detected by a permanent color
Allowing the copper to react with
Bending does not alter
the chemical identity   nitric acid does alter the chemical
identity
Cu + HNO3  H2 + Cu(NO3)2
 The physical and
chemical
properties of
different
substances
influence the
applications for
which they are
used.
 We  are going to start looking at ways to
classify the elements of the periodic
table.
 The two major classes of the elements
are metals and nonmetals.
 Metals are to the left of the stair step
(SS) on the periodic table while
nonmetals are to the right of the SS.
To the left of the SS
Elements form positive ions
(cations)
Of 115 known elements, 88 are
metals
Elements that have a high luster
and high electrical conductivity
To  the right of the SS
Elements form negative ions
(anions)
Tend to be brittle solids or gases
at room temperature
– Low densities/melting points
These  substances have properties
similar to those of metals and
nonmetals
–They exhibit both properties
Border  the SS
Elements form negative or
positive ions
 Each  element is composed of atoms
 Gold atoms differ from sulfur atoms in
the number of protons in the nucleus.
Clockwise
from the
top: sulfur,
antimony,
iodine,
phosphorus,
copper, and
bismuth
Intensive vs. Extensive
Properties
Intensive   Properties
–Do NOT depend on the amount
of substance
–Examples: Density, color,
melting point, phase, ductility,
etc.
Extensive   Properties

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