Name______Class______Date______
10-2: The Atom NOTES
HOW SMALL IS AN ATOM?
_____1.Which of the following statements is true?
a.A penny has about 20,000 atoms.
b.A penny has more atoms than Earth has people.
c.Aluminum is made up of large-sized atoms.
d.Aluminum atoms have a diameter of about 3 cm.
what is an atom made of?
Match the correct description with the correct term. Write the letter in the space provided.
_____2.particle of the nucleus that has no electrical charge
_____3.particle found in the nucleus that is positively charged
_____4.particle with an unequal number of protons and electrons
_____5.negatively charged particle found outside the nucleus
_____6.contains most of the mass of an atom
_____7.SI unit used to express the masses of atomic particles
how do atoms of different elements differ?
8.The simplest atom is the ______atom. It has one ______and one ______.
9.Neutrons in the atom’s ______keep two or more protons from moving apart.
10. If you build an atom using two protons, two neutrons, and two electrons, you have built an atom of ______.
11. An atom does not have to have equal numbers of ______and ______.
Directed Reading A continued
12. The number of protons in the nucleus of an atom is the ______of that atom.
isotopes
_____ 13. Isotopes always have
a.the same number of protons.
b.the same number of neutrons.
c.a different atomic number.
d.the same mass.
_____ 14. Which of the following is NOT true about unstable atoms?
a.They are radioactive.
b.They have a nucleus that always remains the same.
c.They give off energy as they fall apart.
d.They give off smaller particles as they fall apart.
_____ 15. What is the mass number of an isotope that has 5 protons, 6 neutrons, and 5 electrons?
a.1 c. 10
b.11 d. 16
_____ 16. If carbon has an atomic number of 6, how many neutrons does carbon-12 have?
a.12 c. 6
b.8 d. 18
17. Most elements contain a mixture of two or more ______.
18. The weighted average of the masses of all the naturally occurring isotopes of an element is the ______.
forces in atoms
Match the correct definition with the correct term. Write the letter in the space provided.
_____ 19. helps protons stay together in the nucleus
_____ 20. pulls objects toward one another
_____ 21. an important force in radioactive atoms
_____ 22. holds the electrons around the nucleus
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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Section summary–Fill in the blanks
•Atoms are extremely ______. Ordinary-sized objects are made up of very large numbers of atoms.
•Atoms consist of a nucleus, which has ______and usually ______, and ______, located in electron clouds around the nucleus.
•The number of protons in the nucleus of an atom is that atom’s ______. All atoms of an element have the same ______.
•Different isotopes of an element have different numbers of ______in their nuclei. Isotopes of an element share most ______and ______properties.
•The mass number of an atom is the sum of the atom’s ______and ______.
•Atomic ______is a weighted average of the masses of natural isotopes of an element.
•The forces at work in an atom are ______force, ______force, strong force, and weak force.
Original content Copyright © by Holt, Rinehart and Winston; a Division of Houghton Mifflin Harcourt Publishing Company.
Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology1Introduction to Atoms