Hi:) how to do 2(bi)?

4 protons, 5 neutrons, 2 electrons

Explanation:

If you look at the numbers beside Be²⁺, the number 9 is the relative atomic mass and the number 4 is the proton (atomic) number. The relative atomic mass is the sum of the number of protons and the number of neutrons.

Number of protons= proton number.

Hence, number of protons= 4

Number of protons + neutrons= 9

4 + number of neutrons= 9

number of neutrons

= 9 -4

= 5

In an atom, the number of protons and electrons are the same since atoms are electrically neutral. But in an ion, the number of electrons is not equal to the number of protons since the atom gains/ loses electrons to form an ion. A positive sign means that electrons are given away.

Thus, Be gives away 2 electrons to form Be²⁺.

Original number of electrons= 4

Number of electrons in Be²⁺

= 4 -2

= 2

In summary, the number of protons and neutrons in an ion is the same as that of the atom. However, the number of electrons is not the same.