Question

1. the number of electrons in one beryllium atom is

a. 9
b. 5
c. 4
d. 2
note: the legend denotes the states
of elements at a temperature of 25°c.
legend for elements
solid
gas
key
atomic number
symbol
atomic molar mass
common ion charge
(most common form)
periodic table of the first eighteen elements

Explanation:

Step1: Recall the atomic number concept

The atomic number of an element is equal to the number of protons in its nucleus. For a neutral atom, the number of electrons is equal to the number of protons.

Step2: Find beryllium's atomic number

Looking at the periodic table, for beryllium (Be), the atomic number is \(4\). Since it is a neutral atom, the number of electrons is equal to the atomic number.

Answer:

B. \(4\)