Download Packet 4 - 16-17 Periodic Table

Packet #4
The Periodic Table
Reference Table: Periodic Table & Table S
“The Elements”
Development of Periodic Table

Dmitri Mendeleev, a Russian chemist is
given credit for being the first scientist to
arrange elements in a usable manner

Mendeleev observed that when the
elements were arranged in order of
increasing atomic mass, similar chemical
and physical properties appeared at regular
intervals

Mendeleev developed the first periodic
table according to increasing atomic mass
Dmitri Mendeleev
Modern Periodic Table

The modern periodic table is not arranged by
increasing atomic mass, but rather increasing
atomic number

Henry Mosely an English scientist used X-rays to
identify the atomic number of the elements

He arranged elements according to increasing
atomic number which led to the modern atomic
law
Periodic Law

States that the properties of elements are periodic
functions of their atomic numbers

This means that when elements are arranged by
increasing atomic #, those with similar properties
will be located at regular intervals (in the same
group)

The placement of an element on the Periodic
Table gives an indication of the chemical and
physical properties of that element
Periods
Periods

Periods are horizontal rows on the periodic table

Period 1 contains H and He

The number at the beginning of the period
indicates the energy level where valence electrons
are located for atoms in that period
Groups or Families
Groups or Families

Vertical Columns

Elements in a group have the same number of valence
electrons.

Elements in a group have similar properties and react
similarly because they have the same number of valence
electrons (this is known as Periodic Law)
Common Group Names
Group 1: Alkali Metals
Group 2: Alkaline Earth Metals
Groups 3-12: Transition Elements (metals)
Group 17: Halogen Group
Group 18: Noble Gases
Classifying Elements
• Elements are classified as either:
• Metals
• Non-metals
• Metalloids
• Noble Gases
• All elements to the left of it are metals.
• All elements to the right are non-metals except for
Group 18 that are known as Noble Gases, and
• All elements touching the zigzag are called
metalloids.
• Aluminum an Polonium are exceptions, it is a metal
although it touches the zig zag
Metalloids
Noble Gases
Metals
Non-Metals
Classifying Elements
• The most reactive metal on the PT is
francium.
• The most reactive non-metal on the PT is
fluorine.
• Representative Elements: Groups 1, 2, and
13-17 – these groups follow a trend we will
soon discuss.
• Transition Elements: Groups 3-12 – these
elements do NOT follow the general
trends – more than 1 charge produce a
COLOR!!
Metals lose electrons – become (+)
Non-metals gain electrons – become (-)
Most reactive
metal and nonmetal
Representative
Groups – Follow
the “rules”
Transition
Elements – Don’t
follow the
“rules”
•SOLIDS: Most of the elements
of the PT
•LIQUIDS: Hg & Br
•GASES: 11 TOTAL
(always reactive)H2, N2, O2, F2, Cl2
(typically non-reactive)Noble Gases
Liquids – 2
Gases – 11
Solids – the rest of
the elements on the
PT
Properties of Elements
Physical Properties of Metals
• Metallic luster (shine)
• Malleable (can be made into sheets)
• Ductile (can be made into wires)
• Metals are good conductors of heat and
electricity
• Most metals are solids at room temperature or
STP which stands for standard temperature and
pressure (exception is mercury which is liquid at
room temperature).
Properties of Elements
• Elements in Group 1 form compounds that are
soluble like sodium chloride, potassium sulfide
and lithium sulfate.
• Elements in Group 2 form compounds that some
of which are soluble and some are not.
• Density of Group 2 is greater that Group 1 (see
table S).
• Group one can be cut with a knife, elements in
Group2 are harder, and elements in Group 3-12
(transition elements) are much harder.
Properties of Elements
Physical Properties: Non-metals, Metalloids, and
Noble Gases
• Non-metals: Lack metallic luster and are brittle
in the solid phase; they are poor conductors of
heat and electricity; non-metals are usually gases,
molecular solids or network solids (exception is
bromine which is a liquid at room temperature).
• Metalloids: Have some properties of both metals
and nonmetals.
• Noble Gases: Are all gases. Have 8 valence
electrons (helium is the exception with 2).
Properties of Elements
Chemical Properties
• Group 1 & Group 2: Elements in Group 1 react
faster than elements in group 2 because Group 1
only has one valence electron and Group 2
• Non-metal Groups (13-17): Elements in Group 17
react very fast and occur in compounds only;
they need to gain only 1 electron to become
stable.
• Noble Gases: He, Ne, and Ar do not react (these
are known as small noble gases) while Kr, Xe,
and Rn can react with fluorine and oxygen (these
are known as heavier noble gases).
•Reactivity of Metals in Water
Periodic Trends (Table S)
Ionization Energy (IE): The energy
required to lose an electron.
• The lower the IE, the easier it is to lose an
electron
• Remember, metals want to lose electrons, and
non-metals want to gain
Ionization energy down a group
As you go down a group ionization energy
decreases because the number of PELS increase,
and so the valence electrons are further away
from the positive nucleus; there is less attraction
which results in less energy needed to remove
electrons
 Look at the ionization energies on Table S
Li
520
Na
496
K
419
Rb
403

Ionization Energy across a Period

As you go from left to right ionization energy
increases because as you go across a period, the
number of valence electrons increase by 1, and
therefore the less likely an element wants to lose
an electron (on the contrary, they want to gain
them).

Look at ionization energy values on Table S
Li (520)  Ne (2081)
Periodic Trends (Table S)
Electronegativity (EN): The affinity to
gain an electron.
• The larger the EN the more the atom attracts
electrons
• Remember, metals want to lose electrons, and
non-metals want to gain
Electronegativity energy down a group
• As you go down a group EN decreases
because as you go down a group, the
number of PELS increase, and therefore the
outermost shell of electrons is further from
the positively charged nucleus making the
attraction for electrons decrease.
• Look at the electronegativity values on Table S
Li
Na
K
Rb
1.0
.9
.8
.8
Electronegativity across a Period
• As you go from left to right EN
increases because as you go across a
period, the number of valence electrons
increase by 1, and therefore the more
likely an element wants to gain an
electron (metal  non-metal)
• Look at ionization energies on Table S
Li (1.0)  F (4.0)
Periodic Trends (Table S)
Atomic Radius (AR): Is the distance from the
nucleus to the outer valence electrons.
radius increases.
Atomic Radius down a group
• As you go down a group , each element has an extra PEL and
therefore a larger radius
• Look at atomic radius on Table S
Li
155
Na
190
K
235
Rb
248
Atomic Radius Across a Period
• As you go across a period the radius
decreases because as you go across a
period the # of protons in the nucleus
increases which increases the nucleus’ pull
on the electrons.
• Look at atomic radius on Table S
Li (155)  F (57)
Ionic Radius (IR)
• The distance of the nucleus to the
outermost valence electron in an ion.
• Remember that an ion is a charged
particle. Metals lose electrons and
therefore are positively charged ions,
and non-metals gain electrons and
therefore are negatively charged ions.
Ionic Radius
• RULE: Positive Ion (cation)
LOSING AN ELECTRON MEANS THAT THE IONIC
RADIUS IS LESS THAN THE ATOMIC RADIUS
(LOSE = LESS)
AR > IR
• RULE: Negative Ion (anion)
GAINING AN ELECTRON MEANS THAT THE IONIC
RADIUS IS GREATER THAN THE ATOMIC RADIUS
(GAIN = GREATER)
AR < IR
Allotropes
Two or more forms of the same element that differ in
their molecules. Allotropes have different properties.
Oxygen has 2 allotropes: O2 is the oxygen we breathe,
and O3 makes up the ozone layer.
Carbon has many different allotropes which differ in
arrangement of atoms
• Diamond: every carbon bonded to 4 other
carbons = very hard
• Graphite: arranged in sheets or layers = lead
pencils.
• Coal: no definite pattern.
• Buckminsterfullerence: rings of 5 and 6 carbon
atoms, looks like the outside of a soccer ball
Review Questions
1) Which element is in Group 2 and Period 7 of
the Periodic Table?
A) radium
B) manganese
C) radon
D) magnesium
2) On the Periodic Table, an element classified as
a semimetal (metalloid) can be found in
A) Period 4, Group 15
B) Period 3, Group 16
C) Period 2, Group 14
D) Period 6, Group 15
3) Which compound contains an alkali metal
and a halogen?
A) RbCl B) CaCl2 C) CaS D) Rb2S
4) The pair of elements with the most similar
chemical properties are
A) S and Ar
B) Mg and Ca
C) Ca and Br
D) Mg and S
5) As the atoms of the metals of Group 1 in the
ground state are considered in order from top to
bottom, the number of occupied principal energy
levels
A) remains the same
B) decreases
C) increases
6) The elements of Period 2 have the same
A) atomic mass
B) atomic number
C) number of occupied sublevels
D) number of occupied principal energy levels
7) Which atom has the largest atomic radius?
A) Ca B) Mg C) Na D) K
8) As the elements of Group 16 are considered
from top to bottom on the Periodic Table, the
atomic radii
A) decrease and the ionization energies
decrease
B) increase and the ionization energies
decrease
C) decrease and the ionization energies
increase
D) increase and the ionization energies increase
9) As a chlorine atom becomes a negative ion, the
atom
A) gains an electron and its radius increases
B) loses an electron and its radius increases
C) gains an electron and its radius decreases
D) loses an electron and its radius decreases
10) Which of the following elements has the
highest electronegativity?
A) H
B) K
C) Ca
D) Al
11) As a neutral sulfur atom gains two
electrons, what happens to the radius of
the atom?
12) Potassium ions are essential to human
health. The movement of dissolved
potassium ions, K+(aq), in and out of a
nerve cell allows that cell to transmit an
electrical impulse.
What is the total number of electrons in a
potassium ion?
13) The table below shows the EN of selected
elements of Period 2 of the Periodic Table.
(a) On the grid below, set up a scale for electronegativity on the y-axis.
(b) Plot the data by drawing a best-fit line.
(c) Using the graph, predict the electronegativity of nitrogen.