Question 1

Which of the following statements is NOT a postulate of Dalton’s atomic theory?

Accepted Answer

Atoms of the same element can have different masses due to isotopes.

Question 2

J.J. Thomson’s cathode ray tube experiments led to the discovery of which subatomic particle, and what property did he measure?

Accepted Answer

Electron; charge-to-mass ratio

Question 3

Rutherford’s gold foil experiment provided evidence for which of the following conclusions?

Accepted Answer

Atoms are mostly empty space with a small, dense, positively charged nucleus.

Question 4

Which of the following correctly matches a subatomic particle with its charge and approximate mass?

Accepted Answer

Proton: charge $$+1$$, mass $$1 \ \mathrm{amu}$$

Question 5

Which of the following elements is a metalloid and is located along the zig-zag line on the periodic table?

Accepted Answer

Silicon (Si)

Question 6

Which group on the periodic table contains the noble gases, and what is a characteristic property of these elements?

Accepted Answer

Group 18; they are chemically inert due to a full valence shell

Question 7

A main group element forms a $$2-$$ anion. Which of the following could it be?

Accepted Answer

Oxygen (O)

Question 8

Which of the following statements about transition elements is correct?

Accepted Answer

They can form cations with multiple possible charges.

Question 9

How many protons, neutrons, and electrons are present in the isotope $$_{17}^{37}\mathrm{Cl}^-$$?

Accepted Answer

$$17$$ protons, $$20$$ neutrons, $$18$$ electrons

Question 10

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

They have delocalized electrons that can move freely throughout the lattice.

Question 11

A sample of magnesium contains $$78.99\%$$ $$^{24}\mathrm{Mg} ($$mass $$23.985 \ \mathrm{amu}$$), $$10.00\%$$ $$^{25}\mathrm{Mg} ($$mass $$24.986 \ \mathrm{amu}$$), and $$11.01\%$$ $$^{26}\mathrm{Mg} ($$mass $$25.983 \ \mathrm{amu}). $$What is the weighted average atomic mass of magnesium? (Round to two decimal places.)

Accepted Answer

$$24.31 \ \mathrm{amu}$$

Question 12

Which of the following ions is isoelectronic with neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{F}^-$$

Question 13

A transition metal forms two different ions: $$\mathrm{Fe}^{2+}$$ and $$\mathrm{Fe}^{3+}. $$What is the difference in the number of electrons between these two ions?

Accepted Answer

1

Question 14

Which of the following best describes the location and general properties of nonmetals on the periodic table?

Accepted Answer

They are found on the right side of the periodic table and are generally poor conductors of heat and electricity.

Question 15

Which of the following is the correct group number and name for the alkali metals?

Accepted Answer

Group 1; alkali metals

Question 16

A neutral atom of calcium ($$\mathrm{Ca}) $$has an atomic number of $$20. If it $$loses two electrons, what is the resulting ion and its charge?

Accepted Answer

$$\mathrm{Ca}^{2+}$$

Question 17

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, which determine chemical behavior.

Question 18

Which of the following best describes the 'plum pudding' model of the atom?

Accepted Answer

A sphere of positive charge with negatively charged electrons embedded throughout.

Question 19

Which of the following main group elements is most likely to form a $$1+$$ cation?

Accepted Answer

Potassium (K)

Question 20

A sample contains $$70\%$$ $$^{63}\mathrm{Cu} ($$mass $$62.93 \ \mathrm{amu}) $$and $$30\%$$ $$^{65}\mathrm{Cu} ($$mass $$64.93 \ \mathrm{amu}). $$What is the average atomic mass of copper in this sample?

Accepted Answer

$$63.53 \ \mathrm{amu}$$

Atoms, Elements, and the Periodic Table: Key Concepts and Properties

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