Download Atomic Structure… Electrons

2017 SSNI
Atomic Fundamentals
Marissa Reigel
A discussion and activities about the
building blocks of matter.
Matter
Term that describes all of
the physical substances
around us
 your table
 your body
 your pen or pencil
Everything!
Matter…
Anything that
 has mass and
 takes up space (has
volume)
Matter is made up of
different kinds of atoms
Matter…
Includes all things that
can be




seen
tasted
smelled
touched
Does not include
 heat
 sound
 light
Activity: How big is an atom?
Materials
 Sheet of paper
 Scissors
Procedure
 Cut paper in half
 Discard half and cut
remaining sheet
 Repeat 90 times
Models
Often used for things that
are too
 small to be observed
 large to be observed
 difficult to be understood
easily
Models…
In the case of atoms, scientists use large models to
explain something that is very small
 Models of the atom are used to explain data or facts that
were gathered experimentally
 Models are theories
Early Models of the Atom
Empedocles (490 BC)
 Suggested there were four basic elements
•
•
•
•
Earth
Air
Fire
Water
 Ratio of elements determined the substance
• Stone was thought to contain a high amount of earth
• Animals were thought to have a higher ratio of both water
and fire
Early Models of the Atom…
Democritus (550 BC)
 Proposed the universe
was made of empty space
and tiny bits of stuff
called “atomos”
 Atoms could not be
divided
 Reasoned, “All that exists
are atoms and space.
Everything else is
opinion.”
Early Models of the Atom…
John Dalton
 All elements are
composed of indivisible
particles (atoms)
 Atoms of the same
element are the same
 Atoms of different
elements are different
 Compounds consisted of
atoms of different
elements combined
together
Element A atom
Element B atom
Element C atom
Compound with
elements A, B, & C
Early Models of the Atom…
JJ Thomson
 Plum pudding model
 Atom is
• Made of a positively
charged material
(pudding or soup)
• With the negatively
charged electrons
scattered through it
Early Models of the Atom…
Ernst Rutherford




Mostly empty space
Small, positive nucleus
Contained protons
Negative electrons
scattered around the
outside
Early Models of the Atom…
Niles Bohr
 Electrons move in definite
orbits around the nucleus
(like planets around the
sun)
• Nucleus (sun) is composed
of protons and neutrons
• Electrons (planets) orbit
around the nucleus
 Neutrons discovered by
James Chadwick
E
P
P
E
E
Atomic Structure
Nucleus
 Protons
 Neutrons
Electrons
Space
Atomic Structure
If an atom could be
enlarged to the size of a
football stadium…
 The nucleus (protons and
neutrons) would be the
size of a grape or a
marble at midfield
 Orbiting electrons would
be size of salt grains
swirling around the upper
deck
Atomic Structure – Bohr’s model based on
results of Gold Foil Experiment
Atomic Structure – Bohr’s model based on
results of Gold Foil Experiment
(Zinc Sulphide)
Activity: What’s Inside the Atom?
?
Roll marble
Determine the geometric
shape underneath
Atomic Structure…
Electrons
 Tiny, very light particles (negligible mass)
 Have a negative electrical charge (-)
 Move around the outside of the nucleus
Atomic Structure…
Protons





Much larger and heavier than electrons
Have a mass of 1 AMU
Protons have a positive charge (+)
Located in the nucleus of the atom
Atoms with same number of protons are the same
element
Number of protons = atomic number
Atomic Structure…
Neutrons





Large and heavy like protons
Have a mass of 1 AMU
Neutrons have no electrical charge
Located in the nucleus of the atom
Neutralize repulsive force of positive protons
• Acts as a “glue” that keeps protons in the nucleus
Number of protons + number of
neutrons = atomic mass
Isotopes
Atoms that have
 Have the same atomic number
 Have different atomic mass numbers
• Same number of protons
• Different number of neutrons
Isotopes…
Atomic Structure Recap
Describing Atoms
Atomic Number is the number of protons
 In a stable atom, the number of protons equals the
number of electrons
Atomic Mass Number
 Number of protons and neutrons
Atomic Weight
 Average mass of the naturally occurring isotopes of an
element
Pop Quiz!
Which atoms are the same element?




Atom A has 65 protons, 65 neutrons, and 65 electrons
Atom B has 65 protons, 66 neutrons, and 65 electrons
Atom C has 66 protons, 65 neutrons, and 65 electrons
Atom D has 65 protons, 65 neutrons, and 66 electrons
What is the mass of…




Atom A?
Atom B?
Atom C?
Atom D?
Pop Quiz Answers
Which atoms are the same element?




Atom A has 65 protons, 65 neutrons, and 65 electrons
Atom B has 65 protons, 66 neutrons, and 65 electrons
Atom C has 66 protons, 65 neutrons, and 65 electrons
Atom D has 65 protons, 65 neutrons, and 66 electrons
Atoms A, B, and D are the same element
What is the mass of…




Atom A? 130 amu
Atom B? 131 amu
Atom C? 131 amu
Atom D? 130 amu
Periodic Table of the Elements
Ions…
An atom that carries an
electrical charge
 If a neutral atom gains an
electron, the atom
becomes negatively
charged
• Because it has more
negative charges than
positive charges
++
--
Ions…
An atom that carries an
electrical charge
 If a neutral atom loses an
electron, the atom
becomes positively
charged
• Because it has more
positive charges than
negative charges
++
-
-
Ions…
Have either
 More protons than electrons (positive charge)
 More electrons than protons (negative charge)
The number of protons does not change in an ion
The number of neutrons does not change in an ion
So, both the atomic number and the atomic mass
remain the same
Ions…
This atom has lost an
electron
 Now it has one more proton
than electron
 One more proton means one
more positive charge
 This makes the total charge of
the atom POSITIVE
This atom has gained an
electron
 Now it has one less proton
than electron
 One less proton means one
less positive charge
 This makes the total charge of
the atom NEGATIVE
Pop Quiz!
What is the overall charge of an atom that has
 50 protons , 51 neutrons, and 50 electrons?
 50 protons , 51 neutrons, and 49 electrons?
 50 protons , 51 neutrons, and 51 electrons?
Pop Quiz Answers
What is the overall charge of an atom that has
 50 protons , 51 neutrons, and 50 electrons? Neutral
 50 protons , 51 neutrons, and 49 electrons? +1
 50 protons , 51 neutrons, and 51 electrons? -1
Review
 Matter is comprised of
atoms
 Atoms are comprised of
three types of particles
• Protons
• Neutrons
• Electrons
 Protons
•
•
•
•
Define an element
Located in the nucleus
Have a positive charge
Have a mass of 1 amu
 Neutrons
• Located in the nucleus
• Have no charge
• Neutralize protons
repulsive force
• Have a mass of 1 amu
 Electrons
• Orbit the nucleus
• Have a negative charge
• Have a negligible mass
 Isotopes
• Same number of protons
• Different number of
neutrons
Final Exam – Fill in the table
Complete the table.
Atom
Protons
Neutrons
Electrons
A
B
C
80
80
90
80
79
D
E
F
G
95
95
95
90
100
110
Charge
Mass
-1
0
165
90
180
+2
-2
112
Which atoms are the same element?
200
220
Final Exam Answers
Complete the table.
Atom
Protons
Neutrons
Electrons
Charge
Mass
A
B
C
80
80
90
80
85
95
79
81
90
+1
-1
0
160
165
185
D
E
F
G
90
95
95
110
90
100
105
110
90
93
97
112
0
+2
-2
-2
180
195
200
220
Which atoms are the same element?
A and B / C and D / E and F