If two elements have similar
chemical properties, you would
expect them to have _____
A.) similar atomic radii
B.) the same number of electrons in the highest
energy level
C.) the same number of energy levels
D.) similar atomic mass
Properties are based on the number of valence
electrons
Periodic Trends
A property that changes
predictably as you travel down
a group or across a period
  Nuclear
charge measures charge on
nucleus, based on number of protons
  Period
(Nuclear Charge increases)
  Group
(Nuclear Charge increases)
  Electrons
are attracted to the nucleus due to
opposite charges
  Electrons
in lower energy levels “shield”
the electrons in outer energy levels from the
nucleus
  The
attraction between electrons and the
nucleus weakens as you move towards
higher energy levels
  Describes
the size of an atom
  Period
(Atomic Radius decreases):
Li
+3
  same
F
+9
number of shells of electrons but an
increasing nuclear charge (+) pulls the
electrons (-) closer to the nucleus causing the
radius to decrease
  Group
(Atomic Radius increases):
Fr
Li
  increasing
number of inner electron shells
shields the positive charge of the nucleus
causing the radius to increase
The size of an atom
________________ as you go from
left to right on the periodic table
A.) decreases
B.) increases
C.) remains constant
D.) varies at random
The atomic radius of F, Br, and I are
64, 114, and 138 pm respectively.
From this estimate a reasonable
atomic radius of Cl.
A.) 53 pm
B.) 89 pm
C.) 126 pm
D.) 162 pm
E.) 196 pm
  Size
of atom after losing or gaining electron(s)
  Metals
tend to lose electrons
  Radius of a metal ion is smaller than atom
Li
Li+
  Nonmetals
tend to gain electrons
  Radius of a nonmetal ion is larger than atom
F
F-
Why is the radius of a negative ion
always greater than the radius of its
neutral atom?
A.) because repulsion between electrons increases
B.) because electron speeds are reduced
C.) because the electron clouds contract
themselves
D.) because the number of energy levels in
reduced
  amount
of energy required to remove
outermost electron
  Period
(Ionizations Energy increases):
  Increasing nuclear charge makes electrons
more tightly bound to nucleus making
electrons harder to remove
  Group
(Ionization Energy decreases):
  Outer electrons are farther from the
nucleus and more shielded, making them
easier to remove
As you move through a period from
metals to non-metals the ionization
energy
A.) decreases
B.) increases
C.) remains constant
D.) varies at random
Atoms get smaller and electrons are held tighter
as you move across a period
Which of the elements below would
you predict to have the highest first
ionization energy?
A.) Sodium
B.) Aluminum
C.) Calcium
D.) Sulfur
Which of the following factors
contributes to the lower ionization
energy of the higher atomic number
elements in a family?
A.) greater distance from the nucleus
B.) smaller distance from the nucleus
C.) greater nuclear charge
D.) same number of shells of electrons
  Metals
hold their electrons loosely and thus lose
them easily
  Period
(Metallic Character decreases)
  Outer electrons are held increasingly tighter to
the nucleus
  (M  SM  NM)
  Group
(Metallic Character increases)
  Electrons are held increasingly looser by the
nucleus
Which element in Group 15 has the
strongest metallic character?
A.) Bi
Metal
B.) As
Metaloid
C.) P
Nonmetal
D.) N
Nonmetal
  Electronegativity
= attraction for electrons when bonding
  Scale
is from 0 – 4.0, with Fluorine the most
electronegative element assigned the highest value, 4.0
  Period
(Electronegativity increases)
  Increased nuclear charge while number of shells remains
constant strengthens pull on available electrons
  Group
(Electronegativity decreases):
  Increased shielding of nuclear charge by adding shells of
electrons weakens its pull on available electrons
As atoms of elements in Group 16
are considered in order from top to
bottom, the electronegativity of each
successive element
A.) decreases
B.) increases
C.) remains the same

Moving Across a Period:
  Same number of shells of electrons and an increase in
nuclear charge causes the electrons to be more tightly
bound to the nucleus

Moving Down a Group:
  Adding shells of electrons shields the outer electrons,
causing them to be loosely held

Vocabulary:
  Nuclear Charge, Shielding, Atomic Radius, Ionization
Energy, Ionic Radius, Metallic Character, Electronegativity
Atomic Radius decreases
Ionization Energy increases
Metallic Character decreases
Electronegativity increases
Atomic Radius
increases
Ionization Energy
decreases
Metallic Character
increases
Electronegativity
decreases
  Francium
is the most reactive metal
  Metal reactivity increases as you get
closer to Francium
  Fluorine
is the most reactive nonmetal
  Nonmetal reactivity increases as you get
closer to Fluorine
The least reactive element in Group
17 is
A.) Fluorine
B.) Chlorine
C.) Bromine
D.) Iodine
Nonmetals become less reactive as they move away
from fluorine (less electronegative)
Which of the following increases
with increasing atomic number in
group 2?
A.) ionization energy
B.) valence electrons
C.) atomic radius
D.) electronegativity