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Unit 4 - Stevens [Type the document title]
1
Unit 4: Atomic Structure and the Periodic Table
Vocabulary:
Term Definition
Atom
Proton Sub-atomic particle with positive (+) charge; located in nucleus of atom;
determines identity of element
Neutron
Electron Sub-atomic particle with negative charge; much smaller than protons and
neutrons
Nucleus
Valence Electron Electron found in outermost shell of an atom; determines atoms chemical
properties
Atomic Number
Mass number
Atomic Mass Weighted average of masses of isotopes of each atom
Isotope Atom with same # of protons as other atoms of that element, but different #
of neutrons
Ion
Bohr Model Model used to visualize atomic structure
Lewis Dot Structure
pH scale
Acid
Base Compound which increases hydroxide ions (OH-) when dissolved in H2O
Gravitational Force Attraction of objects due to their masses and distance; weakest force
Electromagnetic
Force Force
Weak Nuclear Force
Strong Nuclear Force Holds the atomic nucleus together; Counteracts the electromagnetic force
Periodic Table e
Unit 4 - Stevens [Type the document title]
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Group Vertical (up and down) column of periodic table; elements in group share
chemical properties (same # valence electrons)
Period
Metals
Non-metals usually gases or brittle solids at room temp; are poor conductors; to right of
stair step
Metalloids Have characteristics of metals and non-metals; make up stair step
Section 1: Atomic Structure
Key Ideas
• Know the structure of atoms
• Explain how sub-atomic particles are different in terms of mass, electrical charges, and location in
the atom
• Understand Hydrogen ion concentration in acids and bases, and how the pH scale measures acids
and bases
Vocab:
• Atom Valence Electron Ion
• Proton Atomic Number Bohr Model
• Neutron Mass Number Lewis Dot
• Electron Atomic Mass pH scale
• Nucleus Isotope Acid
Base
Watch video and answer:
How small are atoms? _______________________________________________________
If they are so small, how do we know they exist? __________________________________
__________________________________________________________________________
History of the Atom:
• For thousands of years, many scientists have been trying to figure out what makes up all matter? Of
course, its atoms. But what are they made of? What do they look like? How do they work?
• After many scientists contributions, and many experiments, we now have a __________________
____________________________________, that is supported by all previous evidence
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Progression of the Atomic model and History of the Atom Timeline:
Scientist Picture of Model Name Discovery
Billiard Ball Model
Plum Pudding Model The Electron
The Proton
Bohr Model
Electron Cloud Model Can not predict exactly
where an electron will
be; electrons have erratic
behavior
The Neutron
What are the building blocks of matter? __________________________________________
What is matter? _____________________________________________________________
What are atoms made of?
• Smallest possible unit into which matter can be divided, while still maintaining its properties.
• Made up of:
– _________________________________
– _________________________________
– _________________________________
• The solar system is commonly used as an analogy to describe the structure of an atom
Atoms are so small that:
• It would take a stack of about 50,000 aluminum atoms to equal the thickness of a sheet of aluminum
foil from your kitchen.
• If you could enlarge a penny until it was as wide as the US, each of its atoms would be only about 3
cm in diameter – about the size of a ping-pong ball
• A human hair is about 1 million carbon atoms wide.
• A typical human cell contains roughly 1 trillion atoms.
• A speck of dust might contain 3x1012
(3 trillion) atoms.
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• It would take you around 500 years to count the number of atoms in a grain of salt.
Protons:
• _________________________________________________________________________________
• _________________________________________________________________________________
• _________________________________________________________________________________
• _________________________________________________________________________________
• Help identify the atom (could be considered an atom’s DNA)
Neutrons:
• _________________________________________________________________________________
• _________________________________________________________________________________
• _________________________________________________________________________________
• _________________________________________________________________________________
• Mass number – protons = neutrons
Electrons:
• Negatively charged particles
• Found outside the nucleus of the atom, in the electron orbits/levels;
• Each orbit/level can hold a maximum number of electrons ( 1st = 2, 2
nd = 8, 3
rd = 8 or 18, etc…)
• Move so rapidly around the nucleus that they create an electron cloud
• Mass is insignificant when compared to protons and neutrons (smallest)
• = to number of protons, in a neutral atom
• Involved in the formation of chemical bonds
Valence Electrons:
• _________________________________________________________________________________
• Electrons that can be gained, lost or shared in ____________________________________________
• How many valence electrons does this atom have?
• What element is this atom? __________________________________________________________
Unit 4 - Stevens [Type the document title]
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Bohr Model:
• Even though this model is not correct, we use it to easily visualize what is happening with protons,
neutrons and electrons.
• How do we know that this model is Nitrogen? ___________________________________________
__________________________________________________________________________________
Lewis Dot Structure:
• Lewis Dot Structure shows the number of valence electrons for atoms.
• How many valence electrons does this atom of Nitrogen have? _____________________________
• How many total electrons does it have? ________________________________________________
Draw the Bohr Model of each Atom:
Hydrogen: Oxygen: Sodium:
Sub-Atomic Particle Weight Comparison:
Neutron=1.6749286x10-27
kg
Proton=1.6726231x10-27
kg
Electron = 9.1093897 x10-31
kg
Which particle is smallest? ________________________________________________________________
Which two particles are very similar in size (mass)? ____________________________________________
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Atomic Number:
Same as _________________________________________________________________________
What is the atomic number of this atom? _______________________________________________
Draw this an easier way:
Mass Number:
• _________________ + ______________________
• Tells us the number of protons and neutrons in an atom’s nucleus
• Expressed in Atomic Mass Units (amu)
• Each proton or neutron has a mass of 1 amu
• What is the mass number of the above atom? ____________________________________________
• Why don’t we care about the number of electrons? _______________________________________
_________________________________________________________________________________
What are the atomic and mass numbers (amu) for the following atoms?
Atoms Protons Neutrons Electrons Mass
Number
Atomic
Number Bohr Model
Carbon 6 6 6
Beryllium 4 5 4
Oxygen 8 8 8
Lithium 3 4 3
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Sodium 11 12 11
Average Atomic Mass:
• The weighted average of the masses of all the naturally occurring ____________________________
_________________________________________________________________________________
• The average considers the percent abundance of each isotope in nature
• Found on the periodic table of elements
Ion:
• _________________________________________________________________________________
_________________________________________________________________________________
• If I gain electrons, I get a negative charge _______________________________________________
• If I lose electrons I get a positive charge ________________________________________________
Build the following ions, and determine their atomic and mass numbers.
Atoms Protons Neutrons Electrons Mass
Number
Atomic
Number Bohr Model
Carbon (C3-
) 6 6 9
Hydrogen
(H1+
) 1 0 0
Oxygen (O2-
) 8 8 10
Lithium (Li3+
) 3 4 0
Sodium (Na1-
) 11 12 12
***Be aware that the atomic and mass numbers are not impacted by the loss or gain of electrons.
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Acids and Bases and the pH Scale: (Draw and label the pH Scale)
pH Scale : ______________________________________________
Acids and Bases:
Acid:
• ______________________________________________________________________________
• ______________________________________________________________________________
• ______________________________________________________________________________
• ______________________________________________________________________________
Base (alkaline):
• ______________________________________________________________________________
• ______________________________________________________________________________
• ______________________________________________________________________________
• ______________________________________________________________________________
****pH of 7 is neutral; neither an acid or a base
Section 2: Forces in the Atom:
Key Ideas:
• Understand the magnitude and range of the four fundamental forces
• Recognize the effect of each force on the structure of matter
Vocab:
• Gravitational Force - Strong Nuclear Force
• Electromagnetic Force - Weak Nuclear Force
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Forces
Gravitational Electromagnetic Strong Nuclear Weak Nuclear
• _________________
_________________
_________________
• The amount of
gravity between
objects depends on
their masses and the
distance between
them
• ________________
________________
• ________________
________________
________________
________________
• ________________
________________
• ________________
________________
________________
________________
• ________________
________________
• This force plays a key
role in the possible
change of sub-atomic
particles.
– For example, a
neutron can
change into a
proton(+) and
an electron(-)
• The force responsible
for radioactive decay.
• Radioactive decay
process in which the
nucleus of a
radioactive (unstable)
atom releases nuclear
radiation.
Section 3: The Periodic Table
Key Ideas
• Relate the properties of atoms and their position in the periodic table to the arrangement of their
electrons
Vocab
• Periodic Table - Metal
• Group - Non-Metal
• Period - Metalloid
What is the Periodic Table of the Elements?
• _________________________________________________________________________________
• Resource Information: Nova Interactive Periodic Table
First Organizers:
Dmitri Mendeleev (late 1800’s), Russian chemist
• Organizes first periodic table based on atomic mass, but some elements are out of order
Henry G.J. Moseley (1913), British chemist
• Arranged elements by atomic number, which is what we use today
• Student of Rutherford
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How is the Periodic Table Actually Organized?
Groups:
• ___________________________________________________________________________
• ___________________________________________________________________________
• ___________________________________________________________________________
• Example: Every element in group 1, has 1 electron in its outer shell, every element in group
2, has 2 electrons in its outer shell, and so on (excluding transition metals)
****Remember: Valence Electrons are electrons in the last “shell” or energy level of an atom
Important because:
• Determine an elements ability to “bond” with another element
• Chemical properties depend almost entirely on the configuration of the outer electron shell
(reactivity, flammability, etc.)
Periods:
• ___________________________________________________________________________
• ___________________________________________________________________________
• Each row in a period ends when an outer energy level is filled
• Example: Every element in the top row has 1 orbital for its electrons, 2nd
row has two orbitals
and so on
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Categories of elements in the periodic table:
Alkali Non-Metal
Alkaline Earth Halogens
Transition Metals Noble Gas
Basic metal Lanthanide (rare-earth) - radioactive
Semi metal Actinides (rare-earth) - radioactive
3 Main Categories (you have to know!!!!)
Metals:
• ________________________________________________________________________________________
• All but Mercury are solid at room temp
• ________________________________________________________________________________________
• Alkali Metals – (Group 1) are the most reactive of all metals; don’t occur in nature in their element form
• Alkaline Earth Metals – (Group 2) shiny, ductile and malleable; combine readily with other elements
• Transition Metals – (Group 3 – 12) most familiar metals because they often occur in nature uncombined
• Inner Transition Metals
• Lanthanide Series – elements with atomic # 58-71
• Actinide Series – elements with atomic # 90 - 103
Non-Metals:
Elements that are:
• _________________________________________________________________________________
• are poor conductors
• _________________________________________________________________________________
• Noble gases – (Group 18) exist as isolated atoms. They are all stable because the outer energy level
is filled.
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Metalloids:
• _________________________________________________________________________________
• Have metallic and non-metallic properties (share characteristics with metals and non-metals)
• Part of the mixed groups (groups 13, 14, 15, 16 and 17) – which contain metals, non-metals and
metalloids
How to read the periodic table: (KNOW THIS)
Practice:
Choose 3 elements and draw the box from the periodic table and the Bohr model for each.
1.
2.
3.
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