Download CH. 6 TEST NOTES Completion 1. In 1803 John

CH. 6 TEST NOTES
Completion
1. In 1803 John Dalton proposed that all substances are made of
_____________________.
2. Twentieth-century scientists believe electrons are found in regions
called __________________________.
3. __________________ and _________________ each have a mass of
about 1 amu.
4. Because the mass of a(n) _____________________ is so small, it is
usually thought of as almost zero.
5. Isotopes have different numbers of _____________________.
6. Atoms that are _____________________ of each other are always
the same element.
7. An atom that has gained a charge is called a(n)
_____________________.
8. The sum of the protons and neutrons in an atom is called the
_____________________.
9. Around 440 BCE, Democritus proposed the idea of a(n)
_____________________, a particle that could not be cut.
10. In 1911, Ernest Rutherford proposed that each atom has a(n)
_____________________, a tiny, extremely dense, positively charged
region.
11. Most of the atom's mass is found in the _____________________.
12. All atoms of an element have the same _____________________.
13. A hydrogen atom with one proton in its nucleus has a(n)
_____________________ of one.
14. J.J. Thomson discovered the negatively charged particles called
__________________.
15. Rutherford believed that each atom has a(n) ____________________
at its center.
16. The current atomic theory includes the ____________________
model.
17. The smallest units of an element are ____________________.
18. Isotopes of the same element always have the same number of
____________________.
19. Most elements have a mixture of two or more
____________________.
20. Protons stay together in the nucleus because of
____________________ force.
21. Electrons around the nucleus are held in place by
____________________ force.
22. A positively charged particle in the nucleus of an atom is called a(n)
____________________.
23. An atom of an element that has the same number of protons but
different numbers of neutrons is called a(n) ____________________.
24. The region in an atom that contains most of the mass is called the
____________________.
25. The number of protons in an atom determines its
_________________________.
26. The weighted average of all the naturally occurring isotopes of an
element is called the _________________________.
27. The smallest particle into which an element can be divided and still be
the same substance is a(n) ____________________.
Short Answer
28. Describe the difference between atomic number and atomic mass
number.
Atomic number is only the number of protons. Atomic
mass number is the number of protons PLUS neutrons.
29. How are protons in the nucleus of an atom able to stay close to one
another even though they have the same charge?
The strong force holds them together.
30. Compare protons and neutrons.
Protons are positively charged particles found in the
nucleus of an atom. Neutrons are particles with NO
charge found in the nucleus of an atom.
31. Put the following atomic models in the proper sequence: Rutherford's
model, electron-cloud model, "plum-pudding" model, Bohr's model.
1. "plum-pudding" model
2. Rutherford's model
3. Bohr's model
4. electron-cloud model
32. What happens if the number of electrons and protons in an atom are
not equal?
An ion is formed.
33. What is the effect of electromagnetic force?
The electromagnetic force holds the electrons around
the nucleus of an atom.
34. Calculate the number of neutrons in carbon-12.
carbon-12 (amn=12) - carbon (an=6) = Number of neutrons = 6
35.
Is it possible to have carbon atoms with different numbers of
protons? Explain.
NO, all atoms of the same element MUST have the
same number of protons.
36.
What error did Thomson find in Dalton's atomic theory?
Thomson discovered that atoms are made of smaller
parts.
37.
What is the current model of the atom called?
The electron-cloud model.
38. How is the atomic mass of an element calculated?
By taking a weighted average of the mass numbers of
the isotopes of that element.
39. How do isotopes differ from one another?
In the number of neutrons they have.