Question 1

Which experiment provided the first evidence that atoms have a small, dense, positively charged nucleus?

Accepted Answer

Ernest Rutherford's gold foil experiment

Question 2

According to the Law of Definite Proportions, which statement is correct?

Accepted Answer

All samples of a pure compound contain the same elements in the same proportions by mass.

Question 3

A nitrogen ion has 10 electrons. What is its charge?

Accepted Answer

$$+3$$

Question 4

Which of the following statements about isotopes is TRUE?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 5

Calculate the number of neutrons in an atom with atomic number $$Z = 92$$ and mass number $$A = 235.$$

Accepted Answer

$$143$$

Question 6

Which scientist is credited with organizing the periodic table by increasing atomic mass and predicting undiscovered elements?

Accepted Answer

Dmitri Mendeleev

Question 7

What is the formula mass of $$\mathrm{NaCl}$$ given $$\mathrm{Na} = 22.989\ \mathrm{u}$$ and $$\mathrm{Cl} = 35.453\ \mathrm{u}$$?

Accepted Answer

$$58.442\ \mathrm{u}$$

Question 8

Which of the following best describes a metalloid?

Accepted Answer

A substance with properties intermediate between metals and nonmetals

Question 9

Which group on the periodic table is known as the 'halogens'?

Accepted Answer

Group VII

Question 10

A sample of an element contains 95.00% of isotope A (31.972 u), 0.76% of isotope B (32.971 u), and 4.22% of isotope C (33.967 u). What is the average atomic mass of the element?

Accepted Answer

$$32.07\ \mathrm{u}$$

Question 11

Which of the following is a consequence of the Law of Multiple Proportions?

Accepted Answer

A fixed mass of one element will react with masses of another element in a ratio of small, whole numbers.

Question 12

Which subatomic particle is responsible for the chemical reactivity of an atom?

Accepted Answer

Electron

Question 13

If a titanium ion has a $$2+$$ charge, how many electrons does it have? (Atomic number of Ti is 22)

Accepted Answer

$$20$$

Question 14

Which of the following statements about ions is correct?

Accepted Answer

Cations are formed by losing electrons.

Question 15

Which scientist determined the charge of the electron using the oil drop experiment?

Accepted Answer

Robert Millikan

Question 16

Which property is used to order elements in the modern periodic table?

Accepted Answer

Nuclear charge (atomic number)

Question 17

A lead sample has 124 neutrons. If the atomic number of lead is 82, what is the mass number of this isotope?

Accepted Answer

$$206$$

Question 18

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

Accepted Answer

A positive sphere with electrons embedded throughout

Question 19

Which element is identified by the atomic number $$Z = 7$$?

Accepted Answer

Nitrogen

Question 20

Which of the following is NOT a property of metals?

Accepted Answer

Brittle

Atoms and Elements: Foundations of Atomic Theory and the Periodic Table

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