Subatomic Particles Quiz

The mass number less the atomic number gives the number of _____________.

• Electrons

• Electrons and protons

• Neutrons

• Neutrons and protons

Answer explanation

The mass number is the total number of protons and neutrons in an atom. The atomic number represents the number of protons. Therefore, subtracting the atomic number from the mass number gives the number of neutrons.

The mass number of isotopes are ____________________.

• equal

• different

• divisible by each other

• in small whole number ratios

Answer explanation

The mass number of isotopes is different because isotopes of the same element have the same number of protons but different numbers of neutrons, resulting in varying mass numbers.

Which statement best describes electrons?

• They are positive subatomic particles and are found in the nucleus.

• They are positive subatomic particles and are found surrounding the nucleus.

• They are negative subatomic particles and are found in the nucleus.

• They are negative subatomic particles and are found surrounding the nucleus.

Answer explanation

Electrons are negatively charged subatomic particles that orbit the nucleus of an atom, not found within it. Therefore, the correct statement is that they are negative subatomic particles and are found surrounding the nucleus.

Isotopes are atoms with a variable number of ________________.

• electrons

• protons

• ions

• neutrons

Answer explanation

Isotopes are defined by having the same number of protons but a different number of neutrons. This variation in neutrons leads to different atomic masses, making 'neutrons' the correct answer.

For the isotopes 20Ca40 and 20Ca42, which statement is NOT true?

• There are 20 electrons in both isotopes.

• The number of protons in both isotopes is 20.

• There are 20 neutrons in both isotopes.

• Ca40 has 20 neutrons and Ca42 has 22 neutrons.

Answer explanation

The statement 'There are 20 neutrons in both isotopes' is NOT true. 20Ca40 has 20 neutrons, while 20Ca42 has 22 neutrons, as the number of neutrons is determined by subtracting the number of protons from the mass number.

Each element is defined by the number of ____________________.

• Atoms

• Isotopes

• Neutrons

• Protons

Answer explanation

Each element is defined by the number of protons in its nucleus. Protons determine the element's identity and its position in the periodic table, making them the key characteristic of an element.

Atoms are composed of the subatomic particles; these are _______________.

• electrons and protons

• electrons, protons, and neutrons

• protons and neutrons

• protons only

Answer explanation

Atoms are made up of three types of subatomic particles: electrons, protons, and neutrons. Therefore, the correct answer is 'electrons, protons, and neutrons', as it includes all the essential components of an atom.

If an element is described by these data: Z = 19 and A = 40, which of the following statements is TRUE of the element?

• It has 19 protons and 20 neutrons.

• It has 21 electrons and 19 protons.

• It has 19 protons and 19 neutrons.

• It has 19 electrons and 21 neutrons.

Answer explanation

The element with Z = 19 has 19 protons (atomic number). The mass number A = 40 indicates it has 40 - 19 = 21 neutrons. Thus, the correct statement is: It has 19 protons and 20 neutrons.

If the atomic number of an element is 6 and its mass number is 13, how many protons are contained in the nucleus?

• 6

• 7

• 8

• 13

Answer explanation

The atomic number of an element represents the number of protons in its nucleus. Since the atomic number is 6, this means there are 6 protons in the nucleus.

If the atomic number of an element is 6 and its mass number is 13, how many neutrons are contained in the nucleus?

• 6

• 7

• 8

• 13

Answer explanation

The atomic number (6) represents protons. The mass number (13) is the sum of protons and neutrons. To find neutrons: 13 (mass number) - 6 (protons) = 7 neutrons. Thus, the correct answer is 7.