Question 1

Which of the following statements about Dalton’s Atomic Theory is now known to be incorrect?

Accepted Answer

Atoms of a given element are identical in mass and properties.

Question 2

Which experiment provided the first direct evidence for the existence of the atomic nucleus?

Accepted Answer

Rutherford’s gold foil experiment

Question 3

A neutral atom of chlorine has an atomic number $$Z = 17$$ and a mass number $$A = 35. $$How many protons, neutrons, and electrons does it have?

Accepted Answer

17 protons, 18 neutrons, 17 electrons

Question 4

Which of the following best explains why the atomic masses listed on the periodic table are not whole numbers?

Accepted Answer

They are weighted averages of the masses of all naturally occurring isotopes.

Question 5

Given the following isotopes of neon: $$^{20}_{10}Ne$$ and $$^{22}_{10}Ne$$, what is the difference between them?

Accepted Answer

They have different numbers of neutrons.

Question 6

Which of the following elements is a metalloid?

Accepted Answer

Silicon

Question 7

Which scientist is credited with discovering the electron?

Accepted Answer

J.J. Thomson

Question 8

If an atom has 12 protons, 12 neutrons, and 10 electrons, what is its charge and identity?

Accepted Answer

Mg$$^{2+} ($$Magnesium ion with a 2+ charge)

Question 9

Which of the following is the correct electron configuration for a neutral atom of sodium ($$Z = 11$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^1$$

Question 10

Which of the following best describes the arrangement of elements in the modern periodic table?

Accepted Answer

By increasing atomic number in rows (periods) and columns (groups/families)

Question 11

Which of the following statements about metals is true?

Accepted Answer

They are generally good conductors of heat and electricity.

Question 12

How many electrons can a $$d$$ subshell hold?

Accepted Answer

10

Question 13

Which of the following elements is most likely to form a +1 ion?

Accepted Answer

Sodium

Question 14

Which of the following is the correct Lewis dot structure for chlorine (Cl)?

Accepted Answer

Cl with 7 dots around the symbol

Question 15

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of electrons and protons.

Question 16

A sample of iron contains 91.75% $$^{56}Fe ($$atomic mass = 55.9349 u), 5.85% $$^{54}Fe ($$atomic mass = 53.9396 u), 2.12% $$^{57}Fe ($$atomic mass = 56.9354 u), and 0.28% $$^{58}Fe ($$atomic mass = 57.9333 u). What is the atomic mass of iron? (Round to two decimal places)

Accepted Answer

55.85 u

Question 17

Which of the following is a correct statement about periods and groups in the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 18

Which of the following best describes the role of valence electrons in chemical behavior?

Accepted Answer

Valence electrons determine the chemical reactivity and bonding of an element.

Question 19

Which of the following is the correct order of filling for electron subshells according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d$$

Question 20

Which of the following elements is a liquid at room temperature?

Accepted Answer

Mercury

Atoms and Elements: Structure, Properties, and the Periodic Table

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