Atomic Theory and the Periodic Table Exam Review

The atomic number of carbon is 6. This means that a carbon atom has six...

• A protons in its nucleus.

• B electrons in its nucleus.

• C neutrons in its nucleus.

• D energy levels in its nucleus.

Answer explanation

The atomic number indicates the number of protons in an atom's nucleus. Since carbon has an atomic number of 6, it has six protons in its nucleus, making option A the correct choice.

Tags

NGSS.MS-PS1-1

Refer to the table to answer the following question.


Which two atoms have the same number of protons but a different number of neutrons?

• Atoms W & X

• Atoms X & Y

• Atoms W & Y

• Atoms W & Z

Answer explanation

Atoms W & Z have the same number of protons, indicating they are the same element, but differ in the number of neutrons, making them isotopes of each other. This matches the criteria of the question.

Tags

NGSS.MS-PS1-1

How many protons and neutrons are in one atom of ³²₁₆S?

• 16 protons and 16 neutrons

• 16 protons and 18 neutrons

• 18 protons and 16 neutrons

• 18 protons and 18 neutrons

Answer explanation

In the notation, the bottom number (16) represents protons, indicating there are 16 protons. The top number (32) is the total of protons and neutrons. Thus, neutrons = 32 - 16 = 16. The correct answer is 16 protons and 16 neutrons.

Tags

NGSS.MS-PS1-1

Which of the following is always identical for two isotopes of an element?

• Number of neutrons

• Atomic number

• Atomic mass

• Mass number

Answer explanation

The atomic number, which represents the number of protons in an element, is always identical for isotopes. Isotopes differ in the number of neutrons, affecting their atomic mass and mass number, but not the atomic number.

The natural isotope abundance of copper is shown on the table. Natural Isotope Abundance Isotope Percent Abundance copper-63 69.2% copper-65 30.8% What is the average atomic mass of copper?

• 63.1 amu

• 63.6 amu

• 64.0 amu

• 64.4 amu

Answer explanation

To find the average atomic mass of copper, multiply each isotope's mass by its percent abundance (in decimal form) and sum the results: (63 amu * 0.692) + (65 amu * 0.308) = 63.6 amu. Thus, the correct answer is 63.6 amu.

Which of the following is correct about the isotope Nickel-58?

• Nickel-58 has 58 protons.

• Nickel-58 has 30 neutrons.

• Nickel-58 has 28 neutrons.

• Nickel-58 has 32 protons.

Answer explanation

Nickel-58 has 28 protons, as it is the atomic number of Nickel. To find the number of neutrons, subtract the number of protons from the mass number: 58 - 28 = 30. Thus, Nickel-58 has 30 neutrons.

An atom of Calcium has 20 protons and 20 neutrons. What is the mass number?

• 40

• 20

• 10

• 30

Answer explanation

The mass number of an atom is the sum of its protons and neutrons. For Calcium, with 20 protons and 20 neutrons, the mass number is 20 + 20 = 40. Therefore, the correct answer is 40.

In the Bohr model below, which element is being represented?

• Lithium

• Boron

• Carbon

• Nitrogen

Answer explanation

The Bohr model for carbon shows 6 protons and 6 electrons, with 2 in the first shell and 4 in the second. This configuration matches carbon's atomic number of 6, distinguishing it from lithium, boron, and nitrogen.

Tags

NGSS.MS-PS1-1

How many energy levels would an atom of Phosphorus (P) have?

• A 2

• B 3

• C 4

• D 5

Answer explanation

Phosphorus (P) has an atomic number of 15, which means it has 15 electrons. These electrons are arranged in 3 energy levels (or shells), making the correct answer B 3.

Tags

NGSS.HS-PS1-1

How many electrons does the element Phosphorus (P) have?

• A 15

• B 16

• C 31

• D 46

Answer explanation

Phosphorus (P) has an atomic number of 15, which means it has 15 electrons. Therefore, the correct answer is A 15.

Tags

NGSS.MS-PS1-1