Question 14 of 42beginner🔧 ApplyNumerical2 marks

An atom has 18 neutrons and an atomic number of 17. What is its mass number?

Correct Answer

To find the mass number, we first determine the number of protons. The atomic number of an atom is equal to the number of protons, so the atom has 17 protons.

Next, we use the formula for calculating the mass number. The mass number is the total number of protons and neutrons present in the nucleus.

Step 1: Number of protons = Atomic number = 17 Step 2: Number of neutrons = 18 (given) Step 3: Mass number = Number of protons + Number of neutrons = 17 + 18 = 35

Exercise: Pause and Ponder | Q: 12 | (Page 11)
For More Understanding

Explanation

According to the textbook context, the atomic number of an element is equal to the number of protons in its nucleus. The mass number is defined as the total number of nucleons, which includes both protons and neutrons. Given the atomic number is 17, the atom possesses 17 protons. With 18 neutrons provided, the mass number is calculated as 17 (protons) + 18 (neutrons) = 35.

Solution Steps

  1. Step 1: Identify the number of protons. Since the atomic number is 17, the number of protons is 17.

  2. Step 2: Apply the mass number formula: Mass number = Number of protons + Number of neutrons.

  3. Step 3: Substitute the values: Mass number = 17 + 18 = 35.

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