Transcript Chapter 14.1 The Structure of The Atom

Chapter 14.1 The Structure of The
Atom
Vocabulary
 Electric Charge
 Stable
 Elementary Charge
 Radioactive
 Electron
 Nucleus
 Proton
 Neutron
 Atomic Number
 Isotopes
 Mass number
Electric Charge
 It was once believed that atoms were the smallest
particles of matter
 We now know that matter consists of three basic particles
 Proton
 Neutron
 Electron
 Only two of these product an electric charge
 An electric charge is a fundamental property of matter
that can be positive or negative
Positive and Negative Charges
 There are two different kinds of electric charges; Positive
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and Negative
Which parts of the atom have a positive charge and which
have a negative charge?
A positive and negative charge will attract each other
Two positive charges will repel each other
Two negative charges will also repel each other
Opposites attract!!!
Protons, Electrons, Neutrons
Elementary Charge
 An elementary charge is the
smallest unit of electric charge in
ordinary matter. It is represented by
the letter e
 Atoms can only have whole number
electric charge such as +e, -e, +2e, 3e
 What are the elementary charges for
the pictures to the right?
Nucleus, Protons, Neutrons, Electrons
 The nucleus is located at the CENTER of the atom and
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contains 99% of all the mass and ALL of the positive charge
What do you think is found inside the nucleus? Protons,
neutrons, or electrons
Protons are found in the nucleus and have a positive
charge (+e) EXACTLY opposite to the electron
Electrons are found inside atoms, but OUTSIDE of the
nucleus and have a negative charge (-e) exactly opposite of
a proton
Neutrons are also found inside the nucleus, but have no
electric charge
 The mass of a proton is
1,836 times heavier
than an electron!!!
Forces inside atoms
 Electromagnetic Force – this is causes by the
attraction between the electrons and protons
 Strong nuclear force – This is the strongest force
known to science. It attracts protons and neutrons to
each other at EXTREMELY small distances inside the
nucleus
 Weak nuclear force – This is weaker than both
electromagnetic forces and strong nuclear forces
 Gravity – This is even weaker than weak nuclear
forces inside an atom. Why is gravity so weak in
atoms?
How atoms are different
 We previously learned that atoms from
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different elements are all different from one
another. A gold atom will have different
properties than a silver atom
The number of protons are what determine
the properties of an atoms.
The number of protons is called the atomic
number.
All carbon atoms have the same number of
protons, all hydrogen atoms have the same,
etc.
How many protons in each of the atoms
listed to the right?
Electric Charge
 Complete atoms are ELECTRICALLY NEUTRAL.
 What does this mean?
 It means that they have the same amount of electrons
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and protons
How many protons and electrons are in a hydrogen
atom? Helium atom? Carbon?
We also have ions, which have a different number of
protons and electrons, therefore they have a charge
Positively charged ions have more ____________
Negatively charged ions have more ____________
Isotopes
 All atoms of the same element have the
SAME NUMBER OF PROTONS, but they
can have DIFFERENT NUMBERS OF
NEUTRONS
 ISOTOPES are atoms of the SAME
ELEMENT that have different numbers of
neutrons
 A common element that has isotopes is
carbon. They are all carbon because they
have 6 protons, so what make it an
isotope?
 The ratio between Carbon 14 and Carbon
12 is what is used to carbon date an
object
Carbon Dating
 What country is the Turin Shroud located in?
 Carbon 14 was originally what element?
 How many protons, neutrons, and electrons in Carbon
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14
What is half-life?
How long is Carbon 14’s half-life
What is the purpose of using the rings on the trunk of
a tree to verify the half-life?
Starting at what year does carbon dating no longer
work and why?
Mass Number
 Again isotopes of the same element have the SAME
NUMBER of PROTONS, but a DIFFERENT NUMBER of
NEUTRONS.
 The MASS NUMBER of the isotope tells you the
number of protons plus the number of neutrons
 Aluminum has a atomic number of 13 and a mass
number of 27. How many protons and neutrons does
this isotope of aluminum have?
Radioactivity
 Almost all elements have one of more isotopes that
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are stable
If the nucleus is unstable, it breaks apart.
Carbon 12 and Carbon 13 are stable, but Carbon 14 is
radioactive because the nucleus is unstable, which is
why we use it for carbon dating
Radioactivity is a process in which the nucleus
spontaneously emits particles or energy as it changes
into a more stable isotope
Is radiation always dangerous??
Closing questions
 What determines what element an atom is? Protons,
neutrons, or electrons?
 What is the difference between the ATOMIC NUMBER
and MASS NUMBER?
 How many neutrons are present in a magnesium atom
with a mass number of 24
 Find the number of neutrons in a calcium atom that
has a mass number of 40?
Homework
 Everyone has been assigned a different element
 You will need to make a model of your atom including
the nucleus, the number of protons, neutrons, and
electrons
 MAKE SURE TO HAVE THE RIGHT AMOUNT OF EACH
PARTICLE
 You will then write one paragraph detailing what this
element can be used for
Atom Building Game
 Neutrons are represented by the BLUE MARBLES
 Protons are represented by either the RED or GREEN
MARBLES
 Electrons are represented by the YELLOW marbles
 Each group must build each of the atoms below:
 Lithium (Li)
 Carbon (C)
 Neon (NE)
 Aluminum (Al)
 The winner of the game is the first player to run
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completely out of marbles
Each player should start with 6 blue marbles, 5 green
marbles, and 5 yellow marbles
Each player takes turns adding 1-5 marbles, but not
more than 5. The marbles may include any mixture of
electrons, protons, and neutrons
Marbles played in a turn are added to the marbles
already in the atom
Only atoms where the electrons, protons, and
neutrons match one of the naturally occurring
elements on the table are allowed.
The player must name the element for it to count!!!!