Answer:
Beryllium
Explanation:
Given parameters:
Number of protons = 4
Number of neutrons = 5
Number of electrons = 4
Unknown:
Element = ?
Solution:
To determine an element, the atomic number is the most important identifier.
The atomic number is the number of protons in an atom.
Since the atom here has a proton number of 4, checking on the periodic table, it is Beryllium, Be
