Download Vocabulary and Section Summary

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Skills Worksheet
Vocabulary and Section Summary
The Atom
VOCABULARY
In your own words, write a definition of the following terms in the space provided.
1. proton
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2. atomic mass unit
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3. neutron
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4. atomic number
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5. isotope
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6. mass number
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7. atomic mass
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
14
Introduction to Atoms
Name ______________________________ Class___________________Date__________________
Vocabulary and Section Summary continued
SECTION SUMMARY
Read the following section summary.
• Atoms are extremely small. Ordinary-sized objects are made up of very large
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numbers of atoms.
Atoms consist of a nucleus, which has protons and usually neutrons, and
electrons, located in electron clouds around the nucleus.
The number of protons in the nucleus of an atom is that atom’s atomic number.
All atoms of an element have the same atomic number.
Different isotopes of an element have different numbers of neutrons in their
nuclei. Isotopes of an element share most chemical and physical properties.
The mass number of an atom is the sum of the atom’s neutrons and protons.
• Atomic mass is a weighted average of the masses of natural isotopes of an
element.
• The forces at work in an atom are gravitational force, electromagnetic force,
strong force, and weak force.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
15
Introduction to Atoms