Download Chapter 4 Study Guide Answers 1. All elements

Chapter 4 Study Guide Answers
1. What is the smallest particle of an element that retains the properties of that
element?
An atom
2. What did Dalton hypothesized that about atoms?
1. All elements are composed of tiny indivisible particles called atom.
2. Atoms of the same element are identical. The atoms of any one
element are different from those of any other element.
3. Atoms of different elements can physically mix together or can
chemically combine in simple whole-number ratios to form
compounds.
4. Chemical reactions occur when atoms are separated, joined, or
rearranged.
3. Why did J. J. Thomson reason that electrons must be a part of the atoms of all
elements?
Thomson discovered that the charge-mass ratio did not depend on the type
of gas in the CRT.
4. An element has an atomic number of 76. What are the number of protons and
electrons in a neutral atom?
76 protons and 76 electrons
5. All atoms of the same element have the same _number of protons____.
6. How are isotopes of the same element different?
They differ in the number of neutrons thus, their mass numbers also differ.
7. How many protons, electrons, and neutrons does an atom with atomic number
50 and mass number 125 contain?
50 protons, 50 electrons, 75 neutrons
8. Draw the deflection pattern for the beams of protons, neutrons, and electrons as
they pass through a pair of charged plates.
9. List the number of protons, neutrons, and electrons in Carbon-13.
6 protons, 7 neutrons, 6 electrons
10. What are the postulates of Dalton’s atomic theory? See number 2
11. Which of Dalton’s hypotheses proved to be untrue?
Elements of the same element are not identical…isotopes of a given element
differ in the number of neutrons they contain.
12. What does the atomic number in an atom represent?
The number of protons
13. What does the mass number of an atom represent?
The sum of protons and neutrons
14. What does the number 12 in magnesium-12 represent?
12 is the mass number
15. How many neutrons are in the isotope carbon-14?
14-6 = 8 neutrons
16. If E is the symbol for an element, which two of the following symbols represent
isotopes of the same element?
a) E b) E c) E d) E
17. Which of the following sets of symbols represents isotopes of the same element?
J
J
J
b)
M
M
M
c) L
L
L
d)
Q
Q
Q
a)