Date 2

Atomic Structure

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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.

A Brief History of Modern Atomic Theory

Early John Dalton reviews research of other scientists and proposes the theory that all

1800’s 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 ______Died: ______

·  Where they lived for the majority of their Life:______

·  Education (college, high school, grade school?) ______

·  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


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.


Structure of the Atom

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? ______


Structure of the Atom

Word Bank (use as often as needed)

1 amu positive negative inside the nucleus

about 1/2000 amu neutral outside the nucleus

Part of the Atom / Mass / Charge / Location

Electron

Proton
Neutron

Check Your Understanding

Atom A has ____ protons, ___ neutrons, and ____ electrons.
The atomic number is _____.
The atomic mass number is ______. / Atom B has ____ protons, ___ neutrons, and ____ electrons.
The atomic 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
(Row) / Number of
Orbitals / Maximum Number
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.

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.

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?