College Prep Physical Science

Atomic Theory

Name ______

Unit Vocabulary

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Matter

Element

Atom

Proton

Neutron

Electron

Nucleus

Ion

Scanning tunneling microscope

Atomic number

Valence electrons

Theory

Law

Inference

John Dalton

Dimitri Mendeleev

Isotope

Hypothesis

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Earnest Rutherford Molecule

Compound Atomic Mass

Quarks CERN

Unit Objectives

By the end of this unit you should be able to:

  • Describe the structure of an atom.
  • Compare and contrast the 3 particles that make up an atom based on size, charge and location.
  • Differentiate between an ion and an isotope.
  • Determine how scientists know atoms exist without ever having seen them.
  • Investigate CERN laboratories and the Big Bang Theory.
  • Differentiate between atoms, elements and matter.
  • Create a Summary for an adult audience on Particle Physics.
  • Calculate atomic and mass number of an atom.
  • Differentiate between direct and indirect observations.
  • Develop inference skills.
  • Synthesize observations into descriptions of atomic mass, number and charge.
  • Use a digital interactive animation to create personal definitions
  • Calculate atomic number and atomic mass
  • Cite examples of the history of Atomic Theory and current experiments

“ATOMIC THEORY: How They Discovered Something

Way Too Small to Be Seen”

Excerpt from That’s Not in my Science Book

By: Kate Kelly

Answer each question in the space provided. Be sure to write all answers in your own words. If there are any questions you find confusing, answer them as best you can and mark them for discussion in class.

  1. What is meant by the statement, “…the science of atoms is still in its infancy,”? How long ago was it determined that atoms exist? (137)
  1. Democritus’ came up with the idea of “atomos” (138). What were atomos? What does that word mean? Did his ideas catch on?
  1. How was the scientific definition of the word element different from the Greek definition? (139)
  1. Who was John Dalton? What substance sparked his curiosity? (140)
  1. How did John Dalton define element? (140)
  1. Read the 4 concepts of Dalton’s atomic theory and then list the TWO core concepts of the theory. (141)
  2. WRITE THEM IN THE SPACE PROVIDED ON THE NEXT PAGE**
  1. What did Ernest Rutherford discover in his gold foil experiment? (142-143)
  1. Compare the amount of empty space in an atom to Yankee Stadium (143-144).

John Dalton developed the atomic theory using experimental evidence.

The Atomic Theory states that:

______

Look back at the Scientific Method packet if necessary. Why is this considered a theory and NOT a law or a hypothesis? Explain.

Structure of Matter

Matter is….

Elements are…

Atoms are…

Molecules and Compounds are…

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All atoms are made up of 3 particles: protons, neutrons and electrons.

Label them in the diagram and complete the chart.

Charge / Location / Mass
PROTON
NEUTRON
ELECTRON

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Carefully observe the results of changes made to atomic structure on the Smart Notebook.

Then describe the following in your own words.

  1. Atomic number
  1. Mass number
  1. Atomic charge

Locating Electrons:

-The area around the nucleus where electrons are found is often referred to as the electron cloud. Since electrons are so tiny and constantly moving, it is virtually impossible to pinpoint the exact location of an electron. However, the electron cloud contains energy levels and orbitals and its location can be narrowed down somewhat. Energy levels are regions of the electron cloud and are often shown as rings around the nucleus; the lowest energy levels are closest to the nucleus and they get higher in energy as you move further out. Each energy level contains orbitals, which are regions of space where there is a high chance of locating an electron.

How many energy levels are shown in the diagram? ______

How many energy levels have electrons present? ______

If this atom was neutral overall, how many protons would it contain in its’ nucleus? ______

Based on the paragraph, describe the terms below:

  • Electron cloud
  • Orbital
  • Energy Level

Fill in the table below. A few facts to remember:

  • The atomic number is the number of ______.
  • The mass number is the number of ______.
  • All atoms start out neutral overall (=no charge); that means that the number of ______must be equal to the number of ______.

Element / Atomic Number / Mass Number / Protons / Electrons / Neutrons
Potassium / 40 / 19
Chlorine / 17 / 18
Xenon / 100 / 46
Bromine / 35 / 70
Zinc / 30 / 32
Nickel / 28 / 57
Copper / 59 / 29
Calcium / 20 / 24
Silicon / 14 / 14
Gold / 79 / 81
Uranium / 200 / 98

Isotopes

Atoms of the same element can have different numbers of neutrons; the different possible versions of each element are called isotopes. For example, the most common isotope of hydrogen has no neutrons at all; there's also a hydrogen isotope called deuterium, with one neutron, and another, tritium, with two neutrons. An atom is still the same element even if it is missing a neutron or has an extra neutron. The isotopes of an element, however, have different mass numbers.

Hydrogen / Deuterium / Tritium

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Ions

The atomic number of an element tells you the number of protons (or positive particles) in an atom. A normal atom has a neutral charge with equal numbers of positive and negative particles. A normal atom has a neutral charge with equal numbers of positive and negative particles. That means an atoms with a neutral charge is one where the number of electrons is equal to the atomic number.

Atoms, though, can sometimes lose or gain electrons. When an atom loses electrons, it has a positive charge. When an atom gains electrons, it has a negative charge. An ion is formed when the atom becomes charged by either losing or gaining electrons. We will come back to this idea of ions when we begin bonding.

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  1. In the paragraphs above, find the definition of an isotope and an ion and underline/highlight it.
  1. How does a neutral atom become an ion?
  1. What is different about the isotopes of an element?

CHALLENGE: Fill in the table below. Remember, when an atom loses electrons it becomes ______charged; when it gains electrons, it becomes ______charged.

Ion / Atomic # / Mass # / # Protons / # Neutrons / # Electrons
Iodine-1 / 127 / 53
Silver+1 / 47 / 61
Barium+2 / 56 / 81
Iron+3 / 26 / 56
Sulfur-2 / 16 / 17
Bromine-1 / 35 / 80
Selenium-2 / 79 / 34
Copper+3 / 29 / 35

Atomic Theory Review

Answer the following True or False.

T F 1. Chemistry is the study of matter. It provides answers to the question, “What

is the world made from?”

T F 2. Atoms can be seen with powerful microscopes.

T F 3. Protons and neutrons have positive electrical charges.

T F 4. Atoms are not the smallest units of matter.

T F 5. An isotope has more protons than electrons.

T F 6.Neutral atoms always have the same number of protons and electrons.

T F 7. Ions have the same number of protons and electrons.

T F 8. Ions have no charge.

T F 9. The exact location of an electron can be determined.

Self Check Questions: Fill in the Blank.

1. The center of an atom is called the ______.

2. An atom with more or less electrons than protons is called a ______.

3. ______are atoms that have more or less neutrons than protons.

4. A ______is a positively charged particle in the nucleus of atoms.

5. Particles in the nucleus of atoms that have no electrical charge are called ______.

6. Particles with a negative charge are called ______.

7. The atomic mass is the combination of ______and ______.

Directions: Connect the person with the proper description.

Rutherfordfirst to consider the idea of atoms

Daltonproved that atoms are mostly empty space

Democritusstudying water caused him to consider existence of atoms

Changing An Atom

Complete the following information… Is the larger number the mass number or atomic number???

element: _Helium______element: ______Iron______element: _____Aluminum_____

# protons: ______atomic #: ______# protons: ______

# neutrons: ______mass #: ______# electrons: ______

Atom or IsotopeAtom or IsotopeAtom or Isotope

element: ____Calcium______element: ___Neon______element: _____Carbon_____

# protons: ______atomic #: ______# protons: ______

# neutrons: ______# electrons:______# electrons: ______

atomic weight: ______atomic weight: ______. # neutrons: ______

Atom or Isotope Atom or IsotopeAtom or Isotope

element: _____Fluorine______element: ____Hydrogen_____ element: ______Hydrogen___

atomic #: ______atomic #: ______# protons: ______

mass #: ______# electrons:______# electrons: ______

# electrons: ______# neutrons: ______# neutrons: ______

Atom or IsotopeAtom or IsotopeAtom or Isotope

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