Multiple Choice
How many neutrons are present in an atom of potassium-39?
2. Atoms & Elements
Isotopes
Struggling with General Chemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
An atom with an atomic number of 12 and a mass number of 25 can best be described by which of these?
A
An atom with 12 protons, 25 neutrons, and 12 electrons
B
An atom with 12 protons, 13 neutrons, and 12 electrons
C
An atom with 12 protons, 12 neutrons, and 13 electrons
D
An atom with 13 protons, 12 neutrons, and 12 electrons
Verified step by step guidance1
Identify the atomic number: The atomic number of an atom is the number of protons in its nucleus. For this atom, the atomic number is 12, which means it has 12 protons.
Determine the number of electrons: In a neutral atom, the number of electrons is equal to the number of protons. Therefore, this atom also has 12 electrons.
Understand the mass number: The mass number is the sum of protons and neutrons in the nucleus. For this atom, the mass number is 25.
Calculate the number of neutrons: Use the formula: \( \text{Number of neutrons} = \text{Mass number} - \text{Atomic number} \). Substitute the given values: \( 25 - 12 = 13 \). Therefore, the atom has 13 neutrons.
Verify the description: Based on the calculations, the atom has 12 protons, 13 neutrons, and 12 electrons. This matches the description: 'An atom with 12 protons, 13 neutrons, and 12 electrons.'
Related Videos
Related Practice
