Transcript Atomic Structure & The Periodic Table

Atomic Structure &
The Periodic Table
Chapter 5
Objectives
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Students will be able to:
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Recognize where atoms of some common elements are
found and how they are named.
Describe atomic structure and how that structure
determines an elements identity.
Identify number of proton, electrons, and neutrons using a
periodic table.
Interpret information about an element using a periodic
table.
Evaluate and calculate the number of atomic particles and
the atomic mass using a chocolate chip cookie.
All matter is made of atoms!
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Everything in this room is made up of atoms!
2400 Years Ago….
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Greek philosophers proposed that everything
on Earth was made of only four basic
substances– air, water, fire, and earth.
Everything else contained a mixture of these
substances.
Today chemists know that about 100 basic
substances, or elements, account for
everything we see and touch.
Types of Atoms in Earth’s
Crust and Living Things
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Hydrogen atoms account for about 90% of
the total mass of the universe, but make up
only 1% of the Earth’s crust. Most of these
atoms are combined with oxygen atoms in
the form of water.
Living things contain at least 25 types of
atoms. Primarily oxygen, carbon, hydrogen,
and nitrogen.
Names and Symbols of
Elements
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Elements get their names in many different
ways.
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Magnesium was named for the region in Greece
known as Magnesia.
Lithium comes from the Greek word lithos, which
means “stone”
Neptunium was named after the planet Neptune.
Mg
Np
Li
Element Symbols
Each element has its own unique symbol. For
some elements, the symbol is simply the first
letter of its name.
Hydrogen- H
Sulfur- S
Carbon- C
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The symbols for other elements use the first letter
plus one other letter of the element’s name. The
first letter is capitalized but the second letter is
not.
Aluminum- Al Platinum- Pt
Zinc- Zn
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Element Symbols
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The origin of some symbols, however, are
less obvious.
The symbol for gold is Au.
The symbol for lead is Pb.
The symbol for iron is Fe
Symbols you need to know!!!
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Pb-Lead
Sn-Tin
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Au- Gold
Zn-Zinc
Symbols you need to know
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Ni- Nickel
Mn-Manganese
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K- Potassium
S- Sulfur
Symbols you need to know
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Al- Aluminum
Na- Sodium
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O- Oxygen
C- Carbon
Symbols you need to know
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He- Helium
Hg- Mercury
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I- Iodine
Ag- Silver
Symbols you need to know
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Cu- Copper
Fe- Iron
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Ca- Calcium
Cl- Chlorine
Symbols you need to know
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Si- Silicon
Mg- Magnesium
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Ne- Neon
Ni- Nitrogen
Symbols you need to know
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B- Boron
H- Hydrogen
John Dalton
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In the early 1800’s British scientist John
Dalton proposed that each element is made
up of tiny particles called atoms.
Dalton stated that all of the atoms of a
particular element are identical but are
different from atoms of all other elements.
Daltons theory also assumed that atoms
could not be divided into anything simpler.
Scientist later found that atoms are made of
even smaller particles.
The Structure of an Atom
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A key discovery leading to the current model
of the atom was that atoms contain charged
particles. The charge is either positive or
negative.
The structure of an Atom
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Atoms are composed of three types of
particles--- electrons, protons, and
neutrons.
Proton- Positively charged particle. Inside
the nucleus.
Neutron- An uncharged particle, Has the
same mass as a proton. Inside the nucleus.
Electron- Negatively charged particles that
move around outside the nucleus.
Atomic Structure: Electrons
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Atoms are extremely small. In fact, you could
fit millions of atoms in the period at the end of
this sentence.
Electrons are much smaller than protons or
neutrons. About 2000 times smaller.
They also move about the nucleus very
quickly.
Negative electrons are attracted to the
positive charged protons.
Atomic Numbers
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The identity of an atom is determined by the
number of protons in its nucleus, called the
Atomic number.
Every hydrogen atom- atomic number 1- has
exactly one proton in its nucleus.
Gold has 79 protons which means the atomic
number is 79.
Atomic Mass Numbers
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The total number of protons and neutrons in
an atom’s nucleus is called its atomic mass
number.
While the atoms of a certain element always
have the same number of protons, they may
not always the same number of neutrons, so
not all atoms of an element have the same
atomic mass number.
These are called isotopes.
Chlorine isotopes
Isotopes
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You can find the number of neutrons
in a particular isotope by subtracting
the atomic number from the atomic
mass number.
Atomic Mass
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The atomic mass of the
atoms of an element is
the average mass of all
the element’s isotopes.
Mendeleev
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Russian Chemist:
Dmitri Mendeleev
Arranged elements
based on their physical
and chemical
properties. He
arranged them in rows
on a chart.
In 1869 he produced
the first periodic table of
elements.
Mendeleev
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Mendeleev left some empty spaces where no
known elements fit the pattern. He predicted
new elements would be discovered.
He even described some of the properties of
the unknown elements. Six years after the
periodic table was published an element,
aluminum, was discovered that matched
some of Mendeleev’s descriptions!
Periodic Table
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We call it the periodic
table because it shows
a periodic, or repeating
pattern of properties of
the elements.
The background colors
of the square indicate
whether the element is
a metal, nonmetal, or
metalloid.
Reading the Periodic Table
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The number at the top of the square is the atomic
number- the number protons in an element.
The chemical symbol is an abbreviation for the
element’s name
The name of the element is written below the symbol
The number below the name indicates the average
atomic mass of all the isotopes of the element
The Periodic Table (p. 148-149)
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The color of the element’s symbol indicates
the physical state of the element.
White letters indicate a gas
Blue letters indicate a liquid
Black letters indicate a solid
Groups
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Elements in a vertical column of the periodic
table show similarities in their chemical and
physical properties.
Columns are known as groups
Example: Halogen group: Combine easily
with many other elements and compounds.
Example: Some metals react violently with
water and are all located in the same group.
Period
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Each horizontal row in the periodic table is
called the period.
The chemical properties of the elements
show a progression
Atomic size decreases as you travel across
the periodic table.
Review
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Q: What are the particles that make up an
atom?
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A: Protons, neutrons, and electrons
Review
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Q: The atomic number of potassium is 19.
How does potassium-39 differ from
potassium-41?
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A: Potassium-41 has two more neutrons.
Review
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Q: How is the modern periodic table
organized?
A: By the atomic Number
Review
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Q: What information about an atom’s
properties can you read from the periodic
table.
A: The number of protons in an atom’s
nucleus, the average mass of one atom of
that element, the element’s symbol, and the
elements name.
Review
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Q: Would you expect strontium (Sr) to be
more like potassium (K) or bromine (Br)?
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A: Potassium, because it is closer on the
periodic table
Now We Are Ready for the
Atomic Cookie Activity!
Section 5.3 The Periodic Table
is a Map of Elements
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Objectives:
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Classify elements as metals, nonmetals, and
metalloids.
Identify different groups of elements.
Describe radioactive elements.
How Are Elements Different?
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Each element is located in a different part of
the periodic table, and each has a very
different use.
http://www.dayah.com/periodic/
Periodic Table has distinct
Regions!
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The Periodic Table is like a road map.
Just as a map shows you where your going,
an atoms position on the periodic table
indicates the properties of an element.
The Periodic table has 3 main regions:
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Metals on the left
Nonmental on the right (except- H)
Metalloids in between
The Periodic Table
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An element’s position in the table also
indicates how reactive it is.
Reactive indicates how likely an element is
to undergo a chemical change.
Atoms in Groups 1 & 7 are the most reactive.
Elements in Group 8 are the least reactive.
Most Elements are Metals
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Metals are elements that conduct electricity
and heat well and have a shiny appearance.
They can also be shaped by bending or being
drawn into a long wire. Except for Mercury,
Hg. Mercury is a liquid at room temperature.
Most metals are solid at room temperature.
Reactive Metals
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Group 1: Alkali Metals are extremely reactive.
In fact, Sodium and Potassium are usually
stored in oil, to keep them from reacting with
air. When exposed to air these elements
react rapidly with oxygen and water vapor.
The ions of these metals are important for
life, and play an essential role in the
functioning of living cells.
Reactive Metals
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Group 2: Alkaline Earth Metals are less
reactive than the Alkali metals.
Calcium ions are an essential part of your
diet.
Magnesium is a light, inexpensive metal that
is often combined with other metals and used
in airplane frames.
Transition Metals
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The elements in Groups 3-12
The earliest known elements: Cu, Au, Ag, and
Fe.
Generally less reactive than other metals.
This is why Gold and Silver are easily shaped
and used for jewelry.
Ancient artifacts made from transition metals
can be found, remained unchanged.
You can even find transition metals in foods
you eat!
Transition Metals
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The properties of transition metals make
them very important to industries.
Iron used to make steel- bridges and
buildings
Copper used to make electrical wire
Many are important for modern technology
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Incandescent light bulbs made of tungsten
Platinum is used in catalytic converters
Alloys
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Two or more metals combine to form an alloy.
Alloys can be stronger, less likely to corrode,
and easier to shape than pure metals.
Example: Steel- contains iron, nickel,
chromium, and manganese.
Rare Earth Metals
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Found in the top row of the rows of metals
outside the main body of the periodic table.
Known as lanthanides because they follow
the element lanthanum on the table.
Called Rare Earth Metals because scientist
once thought they were only found in tiny
amounts on Earth. Eventually scientist
learned that they are not SO rare, but they
are hard to isolate in pure form!
Rare Earth Metals
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More and more uses
are being found for the
rare earth metals.
Europium, Eu, is used
as a coating for
television tubes.
Praseodymium, Pr,
provides a protective
coating against harmful
radiation in a welder’s
helmet