Elements and Periodic Table
Chapter 3
Unit- Introduction to chemistry
Mrs. Castro
Lesson 1
Pages 72 – 79
INTRODUCTION TO ATOMS
Introduction to atoms

Atomic Theory
This is the theory that explain with details the
component of the atoms and their organization.
 Grew as a series of models that developed from
experimental evidence. As more evidence was
collected, the theory and models were revised.

Introduction to atoms

Democritus – Greek philosopher – 430 B.C.
 Proposed
that matter was formed of small pieces that
could not be cut into smaller parts.
 He called the particles atoms – means “uncuttable”
 Atoms is the smaller particles that still can be
consider an element.

1600 – people did experiments and the theory
began to take shape.
Introduction to atoms
John Dalton – English chemist
 Dalton’s Atomic Theory:

 All
elements consist of atoms that cannot be divided.
 All atoms of the same element are exactly the same
and have the same mass. Atoms of different
elements are different and have different mass.
 An atom of one element cannot be changed into an
atom of a different element by a chemical reaction.
 Compounds are formed when atoms of more than
one element combine in a specific ratio.
Introduction to atoms

J.J. Thomson – 1897
 Discovered
that the atoms contain negatively charged
particles called electrons.
 He reasoned that atoms must also contain some sort
of positive charge, balance the negative charge of the
electrons.
Introduction to atoms

Ernest Rutherford – 1911
 Suggested
that the atoms is mostly empty space but
has a positive charge at its center (nucleus).
 He called the positively charged particles in an atom’s
nucleus protons.
Introduction to atoms

Niels Bohrs – 1913- Danish scientist
 Suggested
that the electrons are found only in
specific orbits around the nucleus.
 Each possible electron orbit in Bohr’s model has a
fixed energy.
Introduction to atoms

Cloud Model – 1920
 Electron
are moved rapidly within a cloudlike region
around the nucleus.
 An electron’s movement is related to its energy level,
or the specific amount of energy it has.
 Electrons at different energy levels are likely to be
found in different places.
Introduction to atoms

James Chadwick – 1932 – English scientist
 Found
a no electric charge particle. He called
neutron.

Modern model of atom

At the center of the atom is a tiny, dense
nucleus containing protons and neutrons.
Surrounding the nucleus is a cloudlike region of
moving electrons.
Introduction to atoms

Model of Modern Atom:
Introduction to atoms

Important details:
1.
2.
3.
4.
5.
6.
Proton = p+, positive charge
Electron = e-, negative charge
Neutron = n, no charge
The number of protons equals the number of
electrons. As a result, the positive charge is
equals to the negative charge.
The charge balance, make the atom neutral.
Neutrons don’t affect the charge of an atom
because they have a charge of zero.
Introduction to atoms

Answer the following questions:
1.
2.
3.
4.
5.
6.
What is in the center of an atom?
What particles we found inside the center of an
atom?
Where the electrons are found?
Why the atom is neutral?
What is the effect of the neutrons on the charge
of an atom?
If the atom has 8 p+, how many e- does it
have? What is the atom’s charge?
Introduction to atoms

Atomic mass (Z) = n + p+


The mass of the atom is in the nucleus.
Atomic number (A) = p+

Atomic number = eAnswer:
1. Z =
2. A =
3. Element name =
4. Element symbol =
Introduction to atoms

Identify Z, A and element name, electron’s
quantity and proton’s quantity :
A = atomic number
Hydrogen
Z = atomic mass
e- = 1
p+ = 1
Introduction to atoms

Remember:

Atomic mass (Z) = n + p+
 From

this equation: n = p+ - atomic mass (Z)
Atomic number (A) = p+ = e-
Introduction to atoms

Complete the following table:
Atom’s
Name
Symbol
Atomic
number
Atomic
mass
52
128
Sr
p+
38
103
Pb
e-
50
45
82
125
209
Zr
n
126
40
51
Introduction to atoms

Answer
Atom
Name
Symbol
Atomic
number
Atomic
mass
e-
p+
n
Tellurium
Te
52
128
52
52
76
Strontium
Sr
38
88
38
38
50
Rhodium
Rh
45
103
45
45
58
Lead
Pb
82
207
82
82
125
Bismuth
Bi
83
209
83
83
126
Zirconium
Zr
40
91
40
40
51
Introduction to atoms

Isotopes
Atoms with the same number of protons and
different numbers of neutrons.
 Isotopes are identified by its mass number or
atomic mass.
 Examples:

Carbon atomic number is 6. Protons = 6
C-12
C-13
C-14
n=12-6
n=13-6
n=14-6
6
7
8
Atom
Isotope
Isotope
Introduction to atoms
Fill the blanks:
nucleus
1. The ______
is the very small, dense center
of an atom.
2. The positively charged particle of an atom
is called proton
___________.
neutron
3. A particle with no charge is ________.
electron
4. An _______
is the particle of an atom that
moves rapidly in the cloudlike region
around the nucleus.

Introduction to atoms
5.
6.
7.
Atomic number
The ___________
tells the number of
protons in the nucleus of every atom of an
element.
Atoms of the same element that have the
same number of protons but diffrent
isotopes
numbers of neutrons are called _________.
The sum of p+ and n in the nucleus of the
Atomic mass
atom is the _________.
Introduction to atoms
Lesson 2
Pages 80 - 87
ORGANIZING THE ELEMENTS
Organizing the elements





1860 – 63 elements were discovered.
Dmitri Mendeleev discovered a set of patterns that
applied to all the elements.
He noticed that the pattern of properties appeared
when he arranged the elements in order of
increasing atomic mass.
He found that the properties of the elements
repeated.
Properties studies: melting point, density , color
and atomic mass.
Organizing the elements
Mendeleev created the first Periodic Table in
1869.
 This is a table in which is an arrangement of
elements showing the repeating pattern.

Organizing the elements
As scientists discovered new elements and
learned more about atomic structure, the
periodic table changed.
 At the present, the Periodic Table is
arranged in order of increasing atomic
number.
 It is now know that the number of protons in
the nucleus, given by the atomic number,
determines the chemical properties of an
element.

Organizing the elements
Organizing the elements
Organizing the elements

Periodic Table Information;
1.
2.
Atomic number - # p+ and eChemical symbol
1.
2.
3.
3.
Is one or two letters. First letter is capital letter,
second letter is lowercase letter.
Is an abbreviation of the element’s name in English.
Some of them, have symbols that are abbreviations
of their Latin names.
Atomic mass – n + p+
Organizing the elements

Fing the element’s name or symbol.
Element’ name
Symbol
Tin
Na
Barium
Br
Galium
C
Neon
B
Nickel
Al
Organizing the elements

Fing the element’s name or symbol.
Element’ name
Symbol
Tin
Sn
Sodium
Na
Barium
Ba
Bromine
Br
Galium
Ga
Carbon
C
Neon
Ne
Boro
B
Nickel
Ni
Aluminum
Al
Organizing the elements

Find the element, identified by the atomic
number, complete the information:
Atomic
Number
9
12
79
17
53
Name
Symbol
Atomic
mass
p+ and
e-
n
Organizing the elements

Find the element, identified by the atomic
number, complete the information:
Atomic
Number
Name
Symbol
Atomic
mass
p+ and e-
n
9
Fluorine
F
19
9
10
12
Magnesium
Mg
24
12
12
79
Gold
Au
197
79
118
17
Chlorine
Cl
35
17
18
53
Iodine
I
127
53
74
Organizing the elements

Find your name using the element’s symbols

Example: CASTRO
– arbon
 As – Arsenic
 Tr - ________
 O - Oxygen
C
Organizing the elements

An element’s properties can be predicted from their location
in the Periodic Table.
 Period – rows - Are 7
 Group or family – column – Are 18 – Each of them have
different name and properties.
Find the name of the element using the period and
group:
Period
Group
Name
3
14
2
17
5
18
4
8
Lesson 3
Pages 88 – 95
METALS
Metals
Are the majority of elements.
 Properties:

1.
2.
3.
4.
5.
Luster – shiny
Malleability – material is one that can be
hammered or rolled into flat sheets or other
shapes.
Ductile – material is one that can be pulled out,
or drawn into long wires.
Thermal conductivity – transfer heat.
Electrical conductivity – carry electric current.
Metals
Reactivity – react with other substance by
loosing electrons to other atoms.
7. Corrosion – deterioration due to chemical
reaction in the environment.
6.
Metal Classification
I.
Alkali Metals (metales alcalinos)
Group 1
 Most reactive.
 They are never found as uncombined elements
in nature. Always are in compound.
 Some of them are so soft you can cut them with
a plastic knife.
 Low densities and melting point.

Metal Classification
II.
Alkaline Earth metals (metales
alcalinotérreos)





Group 2
Harder and denser.
Melt at high temperature than alkaline metals.
Very reactive, but not as the alkaline.
Never found uncombined in nature.
Metal Classification
III.
Transition metals







Groups 3 to 12
Most are hard and shiny solids.
Mercury is liquid at temperature room.
Except Mercury, they have high melting point
and densities.
Good conductors of heat and electric current.
Very malleable.
Are less reactive than the groups 1 and 2.
Metal Classification
IV.
Metals in mixed groups
Only some of the elements on groups 13
through 17 are metals.
They are: Al, Ga, In, Sn, Tl, Pb, Bi, and Po.


V.
Lanthanides and Actinides (Lantánidos y
Actínidos)
Top row after the main part of the PT.Lanthanides
Below the Lanthanides – Actinides



Not found in nature but are artificially in laboratories.
Metal Classification
VI.
Transuranium Elements (elmentos
transuránicos)


Elements follow uranium (U). These elements
are made or synthesized, when nuclear
particles are forced to crash into one another.
Elements with atomic number greater than
111 do not yet have permanent names or
symbols. In the future, scientists around
the world will agree on permanent names
and symbols for these elements.
Metals
Lesson 4
Pages 96 - 105
NONMETALS AND METALLOIDS
Nonmetals and metalloids

Nonmetals:
Elements that lacks most of the properties of a
metal.
 Except for H, the non metals are found on the
right side of the PT.
 Properties:

 Poor
conductors of electric current and heat.
 Solid nonmetals are dull and brittle.
 Lower densities that metals.
 Most are gases at room temperature.
Nonmetals and metalloids

Properties cont.
 Usually
gain or share electrons when they react with
other atoms.

The families that containing nonmetals include
the carbon family, nitrogen family, oxygen
family, halogen family, the noble gases and
hydrogen.
 Complete
blue table on page 99.
Nonmetals and metalloids

Carbon family:
Group 14
 Only Carbon is nonmetal.
 It is an important element for life.


Nitrogen family:
Group 15
 Nitrogen and Phosphorus are nonmetals.

Nonmetals and metalloids

Oxygen family:
Group 16
 Oxygen, sulfur and selenium are nonmetals.


Halogen Family:
Group 17
 Fluorine, chlorine, Bromine and iodine are
nonmetals.
 Astatine (At) are rare and properties are unknown.
 Are vary reactive. Fluorine are the most reactive.

Nonmetals and metalloids


Noble gases:
 Group 18
 Do not form compounds because do not gain, lose or
share electrons.
 Nonreactive.
Hydrogen:
 The element with the simplest atom.
 The properties are very different from those of the other
element, so it cannot be grouped in with a family.
 Is rarely found on earth as a pure element. It found
combined with oxygen as water.
Nonmetals and metalloids

Metalloids:
Are between metals and nonmetals.
 They have some properties of metals and some
form nonmetals.
 Are solids at room temperature.
 Brittle, hard and somewhat reactive.
 Most common is Silicon. Is in sand.
 The conductivy of electric current , depend on
temperature, exposure to light or presence of
impurities. Some of them are semiconductors.

Practice

First find the name and then classify the
following elements in metals, nonmetals and
metalloids:
1. Si
3. Br
5. Co
7. Cs
9.Sb
2.Rh
4. Eu
6. F
8. Pb
10. Ag
Fun Practice
END