Question 1

Which statement best summarizes Dalton's Atomic Theory as it was originally proposed in 1808?

Accepted Answer

Each element is composed of tiny, indestructible particles called atoms.

Question 2

In Rutherford's gold foil experiment, most alpha particles passed straight through the foil. What did this observation lead to regarding atomic structure?

Accepted Answer

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

Question 3

Which of the following correctly describes the charge and relative mass of a neutron?

Accepted Answer

No charge, mass nearly equal to a proton

Question 4

A neutral atom of magnesium has an atomic number $$Z = 12$$ and a mass number $$A = 24. $$How many protons, neutrons, and electrons does it have?

Accepted Answer

12 protons, 12 neutrons, 12 electrons

Question 5

Which of the following elements is a metalloid and acts as a semiconductor?

Accepted Answer

Silicon (Si)

Question 6

Which group in the periodic table contains elements that are all diatomic and very reactive nonmetals?

Accepted Answer

Group 7A (halogens)

Question 7

A fluorine atom gains one electron to form an ion. What is the charge and electron count of the resulting ion?

Accepted Answer

Charge: $$-1$$, Electrons: $$10$$

Question 8

Which of the following best explains why the atomic mass of chlorine listed on the periodic table is not a whole number?

Accepted Answer

It is the weighted average of the masses of all naturally occurring isotopes of chlorine.

Question 9

A sample of silver contains two isotopes: $$^{107}Ag ($$mass = $$106.90509$$ amu, abundance = $$51.84\%) $$and $$^{109}Ag ($$mass = $$108.90476$$ amu, abundance = $$48.16\%). $$What is the atomic mass of silver? (Round to two decimal places.)

Accepted Answer

$$107.87$$ amu

Question 10

Which of the following elements is most likely to form a $$2+$$ cation based on its position in the periodic table?

Accepted Answer

Calcium (Ca)

Question 11

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 12

A potassium ion has 19 protons and 18 electrons. What is its charge?

Accepted Answer

$$+1$$

Question 13

Which of the following best describes the trend in metallic character as you move from left to right across a period in the periodic table?

Accepted Answer

Metallic character decreases.

Question 14

Which of the following is a correct representation of a carbon isotope with 7 neutrons?

Accepted Answer

$$^{13}C$$

Question 15

A neutral atom of phosphorus has 15 protons and 16 neutrons. What is its mass number and symbol?

Accepted Answer

Mass number: $$31$$, Symbol: $$^{31}P$$

Question 16

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full outer shell of electrons.

Question 17

Which of the following is a property of metals?

Accepted Answer

They are good conductors of heat and electricity.

Question 18

A sample contains $$70\%$$ $$^{63}Cu ($$mass = $$62.9296$$ amu) and $$30\%$$ $$^{65}Cu ($$mass = $$64.9278$$ amu). What is the atomic mass of copper in this sample? (Round to two decimal places.)

Accepted Answer

$$63.53$$ amu

Question 19

Which of the following elements is most likely to be found as a diatomic gas at room temperature?

Accepted Answer

Chlorine ($$Cl_2)$$

Question 20

Which of the following best describes the difference between cations and anions?

Accepted Answer

Cations are positively charged ions formed by losing electrons; anions are negatively charged ions formed by gaining electrons.

CHM1032.0001 General Chemistry – Syllabus and Course Information

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