Question

the table shows some characteristics of a few atoms. element carbon (c) chromium (cr) magnesium (mg) sodium (na) atomic particles atomic number 6 24 12 11 number of? 6 20 12 12 mass 12 52 24 23 the mass of an element is the sum of the atomic number and the number of
○ electrons.
○ ions.
○ neutrons.
○ protons.

Explanation:

Step1: Recall mass - number formula

The mass number of an element is the sum of the atomic number and the number of neutrons. Mathematically, $Mass\ number=Atomic\ number + Number\ of\ neutrons$.

Step2: Identify the missing particle

Since the mass of an element is the sum of the atomic number and the number of neutrons, the missing particles are neutrons.

Answer:

neutrons