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Chapter 4Review and Assessment

Standardized Test Prep

Test Taking Tip

Connectors Sometimes two phrases in a true/false question are connected by a word such as because or therefore. These words imply a relationship between one part of the sentence and another. Statements that include such words can be false even if both parts of the statement are true by themselves.

Select the choice that best answers each question or completes each statement.

(1)An atom composed of 16 protons, 16 electrons, and 16 neutrons isHint

(2)Which list contains elements that fall within the same group on the periodic table?Hint

  1. He, Ar, Xe
  2. O, F, Ne
  3. K, Rb, Ba
  4. H, He, Li

(3)Which of these descriptions is incorrect?Hint

  1. proton: positive charge, in nucleus, mass of ≈ 1 amu
  2. electron: negative charge, mass of ≈ 0 amu, in nucleus
  3. neutron: mass of ≈ 1 amu, no charge

(4)Thallium has two isotopes, thallium-203 and thallium-205. Thallium’s atomic number is 81 and its atomic mass is 204.38 amu. Which statement about the thallium isotopes is true?Hint

  1. There is more thallium-203 in nature.
  2. Atoms of both isotopes have 81 protons.
  3. Thallium-205 atoms have fewer neutrons.
  4. The most common atom of thallium has a mass of 204.38 amu.

Use the art to answer Question 5.

(5)How many nitrogen-14 atoms (14N) would you need to place on the right pan to balance the three calcium-42 atoms (42Ca) on the left pan of the “atomic balance” below? Describe the method you used to determine your answer, including any calculations.Hint

(6)Which of the following statements about the periodic table are correct?Hint

  1. Elements are arranged in order of increasing atomic mass.

  2. A period is a horizontal row.

  3. The properties of the elements within a period vary from element to element.

  1. I only
  2. I and II only
  3. I, II, and III
  4. I and III only
  5. II and III only

For each question below there are two statements. Decide whether each statement is true or false. Then decide whether Statement II is a correct explanation for Statement I.

(7)Every aluminum-27 atom has 27 protons and 27 electrons.

BECAUSE

The mass number of aluminum-27 is 27.Hint

(8)Isotopes of an element have different atomic masses.

BECAUSE

The nuclei of an element’s isotopes contain different numbers of protons.Hint

(9)An electron is repelled by a negatively charged particle.

BECAUSE

An electron has a negative charge.Hint


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