elements and periodic table chapter 3 unit- introduction to chemistry mrs. castro
TRANSCRIPT
Elements and Periodic TableChapter 3
Unit- Introduction to chemistry
Mrs. Castro
INTRODUCTION TO ATOMS
Lesson 1
Pages 72 – 79
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. Proton = p+, positive charge
2. Electron = e-, negative charge
3. Neutron = n, no charge
4. The number of protons equals the number of electrons. As a result, the positive charge is equals to the negative charge.
5. The charge balance, make the atom neutral.
6. Neutrons don’t affect the charge of an atom because they have a charge of zero.
Introduction to atoms
Answer the following questions:1. What is in the center of an atom?
2. What particles we found inside the center of an atom?
3. Where the electrons are found?
4. Why the atom is neutral?
5. What is the effect of the neutrons on the charge of an atom?
6. 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 = e-
Answer: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 :
Z = atomic mass
A = atomic number
Hydrogen
e- = 1p+ = 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
e- p+ n
52 128
Sr 38 50
103 45
Pb 82 125
209 126
Zr 40 51
Introduction to atoms
AnswerAtom 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:
1. The ______ is the very small, dense center of an atom.
2. The positively charged particle of an atom is called ___________.
3. A particle with no charge is ________.
4. An _______ is the particle of an atom that moves rapidly in the cloudlike region around the nucleus.
nucleus
proton
neutron
electron
Introduction to atoms
5. The ___________ tells the number of protons in the nucleus of every atom of an element.
6. Atoms of the same element that have the same number of protons but diffrent numbers of neutrons are called _________.
7. The sum of p+ and n in the nucleus of the atom is the _________.
Atomic number
isotopes
Atomic mass
Introduction to atoms
Read pages 73 to 79.Perform all the excises.
ORGANIZING THE ELEMENTS
Lesson 2
Pages 80 - 87
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. Atomic number - # p+ and e-
2. Chemical symbol 1. Is one or two letters. First letter is capital letter,
second letter is lowercase letter.
2. Is an abbreviation of the element’s name in English.
3. Some of them, have symbols that are abbreviations of their Latin names.
3. 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
Name Symbol Atomic mass
p+ and e-
n
9
12
79
17
53
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
C – arbon As – Arsenic Tr - ________ O - Oxygen
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
METALS
Lesson 3
Pages 88 – 95
Metals
Are the majority of elements. Properties:
1. Luster – shiny
2. Malleability – material is one that can be hammered or rolled into flat sheets or other shapes.
3. Ductile – material is one that can be pulled out, or drawn into long wires.
4. Thermal conductivity – transfer heat.
5. Electrical conductivity – carry electric current.
Metals
6. Reactivity – react with other substance by loosing electrons to other atoms.
7. Corrosion – deterioration due to chemical reaction in the environment.
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
Let made some excises
NONMETALS AND METALLOIDS
Lesson 4
Pages 96 - 105
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 2.Rh
3. Br 4. Eu
5. Co 6. F
7. Cs 8. Pb
9.Sb 10. Ag
Fun Practice
PERFORM ALIEN PERIODIC TABLE ON PAGES 104 - 105
Period Table Exercise – See teacher for instructions
Review and assessmentPages 115 -116
END
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