Download Section 2 – A Guided Tour of the Periodic Table

Section 2 – A Guided Tour
of the Periodic Table
Chapter 4 Study Guide
Definitions
Periodic law:
• The law stating that repeating
chemical and physical properties
of elements change periodically
with the atomic numbers of the
elements
Period:
• Horizontal rows
of elements
K
Ca
Sc
Ti
V
Group:
• Vertical
columns of
elements
• Elements in the
same group
have similar
properties
Li
Na
K
Rb
Cs
Ion:
• Atoms that either lose electrons
or gain electrons
–Have positive or negative
charge
Atomic number:
• The number of Protons an
element has
• Determines the sequence of the
periodic table
Mass number:
• The total number of subatomic
particles
–Mass # = Protons + Neutrons
Isotope:
• Atoms of an element that have
different numbers of neutrons
–Carbon-12, Carbon-14
Atomic mass unit (amu):
• Standard unit of atomic mass,
equal to one-twelfth the mass of a
Carbon-12 atom
Average atomic mass:
• A weighted average of the
masses of all naturally occurring
isotopes. More common isotopes
count more than less common
ones.
Questions?
Objecive 1: Relate the
organization of the periodic
table to the arrangement of
electrons in an atom.
Objective 1
• (1) The order of elements in the
periodic table is based on the
number of protons in the nucleus.
Objective 1
• (2) Atoms of elements that are in
the same group have the same
number of valence electrons.
Objective 1
• (3) Valence electrons determine
an atom’s chemical properties.
Objective 1
• (4) The periodic table organizes
elements into groups that have
similar properties.
Objective 1
• (5) Magnesium (Mg) is located
to the right of sodium (Na)
because Mg has more electrons
and more protons.
Objective 1
• (6) Elements that have one
valence electron tend to be
highly reactive, form ions, and
become charged.
Objective 1
• (7) The order of elements in the
periodic table is based on the
number of protons in the nucleus.
Objective 1
• (8) Because atoms of elements in
the same group of the periodic
table have the same number of
valence electrons, they have
similar properties.
Objective 1
• (9) The periodic law states that
when elements are listed in order
of atomic number, similarities in
their properties will emerge in a
regular pattern.
Questions?
Objective 2: Explain why some
atoms gain or lose electrons to
form ions.
Objective 2
• (10) Ionization refers to the
process of losing or gaining
electrons.
Objective 2
• (11) A lithium ion is much
less reactive than a lithium
atom because it has a
full outermost energy level.
Objective 2
• (12) Some elements are highly
reactive because their outermost
energy levels are only partially
filled.
Objective 2
• (13) The valence electron of a
lithium atom is easily removed to
form a lithium ion or cation with a
charge of 1+.
Questions?
Objective 3: Determine how
many protons, neutrons, and
electrons an atom has, given its
symbol, atomic number, and
mass number.
Objective 3
• (14) Oxygen’s atomic number is
8. This means that an oxygen
atom has eight protons in its
nucleus.
Objective 3
• (15) An atom’s mass number
equals the number of protons plus
the number of neutrons.
Objective 3
• (16) An element’s atomic number
is equal to its number of protons.
Objective 3
• (17) Two different isotopes of
an element have different
number of neutrons.
Objective 3
• (18) The mass number of an
element that has 19 protons,
19 electrons, and 20 neutrons
is 19 + 20 = 39.
Objective 3
• (19) As you move left to right
across the periodic table,
elements have more protons and
higher mass numbers.
Objective 3
• (20) An iron atom has an
atomic mass of 56. Its atomic
number is 26. This iron atom
has 56 – 26 = 30 neutrons.
Objective 3
• (21) An atom of potassium has an
atomic mass of 39 amu and an
atomic number of 19. It therefore
has 39 – 19 = 20 neutrons in its
nucleus.
Questions?
Objective 4: Describe how the
abundance of isotopes affects
an element’s average atomic
mass.
Objective 4
• (22) An element’s average atomic
mass is a weighted average, so
common isotopes have a greater
effect than uncommon ones.
Objective 4
• (23) An atomic mass unit is equal
to one-twelfth the mass of a
carbon-12 atom.
Objective 4
• (24) More abundant isotopes will
have more effect on the average
atomic mass of an element.
Objective 4
• (25) An element’s average atomic
mass refers to the weighted
average of the masses of all of its
naturally occurring isotopes.
Objective 4
• (26) Isotopes of an element have
the same atomic number but
different atomic mass.
Questions?