Lesson 2.5 Subatomic Particle Practice Questions

What is the total number of electrons in an atom of magnesium?

• 11

• 12

• 24

• 36

Isotopes of an element must have different

• atomic numbers

• numbers of protons

• mass number

• numbers of electrons

The nucleus of an atom of K-42 contains

• 19 protons and 23 neutrons

• 19 protons and 42 neutrons

• 20 protons and 19 neutrons

• 23 protons and 19 neutrons

What is the total number of neutrons in an atom of

• 26

• 57

• 31

• 83

Atoms of different isotopes of the same element differ in their total number of

• Electrons

• Protons

• Neutrons

• Valence Electrons

An atom of potassium-37 and an atom of potassium-42 differ in their total number of

• Electrons

• Neutrons

• Protons

• Positrons

The total mass of the protons in an atom of gold-198 is approximately

• 79 atomic mass units

• 119 atomic mass units

• 198 atomic mass units

• 277 atomic mass units

Each diagram represents the nucleus of a different atom. Which diagrams represent nuclei of the same element?

• D and E, only

• D, E, and Q

• Q and R, only

• Q, R, and E

Which phrase describes a compound that consists of two elements?

• a mixture in which the elements are in a variable proportion.

• a mixture in which the elements are in a fixed proportion.

• a substance in which the elements are chemically combined in a variable proportion.

• a substance in which the elements are chemically combined in fixed proportion.

The arrangement of the elements from left to right in Period 4 on the Periodic Table is based on

• atomic mass

• atomic number

• the number of electron shells

• the number of oxidation states