1
8th
Atomic Structure
1-1
Date
2
Atomic Theory and Organizing the Elements
What you need to know:
 Atoms are the smallest complete particle of matter.
 Atoms have central core called the nucleus.
 The atomic nucleus is composed of protons and neutrons.
 Protons have a positive charge (+).
 Neutrons have a neutral charge (0).
 Neutrons and protons are made of smaller particles called quarks.
 A cloud of electrons surrounds the nucleus.
 Electrons have a negative charge (-).
 Elements can be arranged in a periodic table based on atomic number.
 Elements in a column (group or family) have similar properties
 The three main types of elements are metals, metalloids, and nonmetals.
 Nuclear reactions involve changes in the nucleus.
Modern Atomic Theory
1. Atoms are the smallest complete unit of matter.
2. Atoms can be broken down into three main component particles: electrons, protons, and
neutrons. Protons and neutrons can be further broken down into quarks.
3. In any element, all the atoms have the same number of protons. Atoms with a different
number of neutrons are called isotopes.
4. Atoms of different elements are different.
5. Atoms of two or more elements can combine to form compounds.
6. The average atomic weight (mass) of an element reflects the average of all its isotopic forms,
but is unique to the element.
7. Atoms of elements in a compound combine in a constant ratio.
Date
3
A Brief History of Modern Atomic Theory
Early
1800’s
John Dalton reviews research of other scientists and proposes the theory that all
matter is composed of tiny indivisible particles called atoms.
1897
Joseph John (J.J.) Thomson discovers the electron, a negative subatomic particle.
1909
Ernest Rutherford discovers that most of the volume of the atom is empty space.
1915
Niels Bohr proposes a model of the atom in which electrons move in orbitals
around a dense core called the nucleus.
1919
Ernest Rutherford discovers the proton, a positive subatomic particle.
1932
James Chadwick discovers the neutron, a neutral subatomic particle.
1935
Hideki Yukawa proposes the idea that neutrons and protons are composed of
smaller particles.
1973
Murray Gell-Mann leads the development of the quark theory that explains the
charges of protons and neutrons.
Chemist Facebook Page Project Total 30 Points:
Directions: Together we will put together a history of chemist time line, starting with the
discovery of the atom. You will be working by your self to complete this project. Use the internet
to research information about your chemist. Below are the Criteria for Your Chemist Facebook
Page.
Fill out the graphic organizer below before you move on to the LARGE FACEBOOK PAGE!!
1. Information that must be on the page (10 points)

Date of Discovery _____________

Full Name of Scientist:________________________________

Nickname if they had one___________________

Born __________________

Where they lived for the majority of their Life:____________________________

Education (college, high school, grade school?) ____________________
Died: ____________________
Date
4

Discoveries major discoveries: _______________________________________

Hobbies or Interests___________________

Books written, if any _________________________
2. Pictures (10 points)
-Pictures of your chemists
-Picture of his discoveries or books written
3. Neatness (10 points)
-
color
information written or typed neatly
creative presentation
Date
5
Structure of the Atom
Definitions
Nucleus
central core of the atom composed of protons and usually neutrons
Proton
a small particle in the nucleus of the atom with a positive charge
Neutron
a small particle in the nucleus of the atom with no electrical charge
Orbital
energy shell around the nucleus where electrons are found
Electron
a tiny particle with a negative charge that moves around the nucleus of an atom
Valence
the outer orbital of an atom; valence electrons are the farthest from the nucleus
and are involved in chemical reactions between atoms
How many protons are in the atom shown above?
How many neutrons are in the atom shown above?
How many electrons are in the atom shown above?
Complete the Statement:
An atom has a neutral charge when the number of electrons is the same as the number of
.
NOTE: Only two electrons may occupy the first orbital.
Date
Structure of the Atom
6
Definitions
Atomic number
the number of protons in the nucleus of an atom
Atomic mass
the average mass of one atom of an element
Atomic mass unit
a unit used to measure the mass of particles in atoms; the proton and
neutron each have a mass of 1 amu; an electron has a mass of 1/2000
amu
Atomic mass number
the sum of the number of protons and neutrons in an atomic nucleus
Isotope
atoms with the same number of protons, but a different number of
neutrons and different atomic mass number
Use the definitions to follow the instructions.
The dotted lines represent electron orbitals. The shaded center circle represents the nucleus.
Fill in 4 protons, 5 neutrons, and 4 orbital electrons for element 4 of the periodic table. Show
the charges for the protons and electrons.
If the atomic number is the number of protons, what is the atomic number of this element?
_____________
If the atomic mass number is the total of the number of protons and number of neutrons, what
is the atomic mass number of this element? _________________
Isotopes have the same number of protons and different numbers of neutrons. The atomic mass
of element 4 Is 9.012 amu. Does this element have isotopes? ______________
Date
Structure of the Atom
Word Bank (use as often as needed)
1 amu
positive
about 1/2000 amu
neutral
Part of the Atom
7
Mass
negative
Charge
inside the nucleus
outside the nucleus
Location
Electron
Proton
Neutron
Check Your Understanding
Atom A has ____ protons, ___ neutrons, and ____
Atom B has ____ protons, ___ neutrons, and
electrons.
____ electrons.
The atomic number is _____.
The atomic number is _____.
The atomic mass number is ______.
The atomic mass number is _____.
The outermost ring of electrons is called the valence. The electrons are called the valence
electrons.
Filling Rules for Orbitals 1-3
Period Number of Maximum Number
(Row)
Orbitals
of Electrons
1
1
2
2
2
2, 8
3
3
2, 8, 8
NOTE: Rules for filling orbitals after 3 are more complicated, especially the transition metal
elements. In general, the last orbital, or valence, may never have more than 8 electrons.
Date
8
IONS
Directions: use the word box to fill out the following information about ions. Cross out the word
once you use it. You can use a word more then once.
Electrons
Negative
Electron
Positive
Ion
(Net
Lost
Charge)
Gained
Positive
Negative
In a neutral atom the # number of protons = the # of ________________________
The ________________________ charges of the protons and the negative charges of the
________________equal each other for a net charge of zero.
A ______________________ is an atom that has gained or lost __________________________________
Ions have a ______________ ____________________, either positive or negative.
Why aren’t protons lost or gained?