A) Represent element Y using the atomic symbol notation ^A_Z Y. b) Draw the atomic structure of element Y, indicating the number of protons and neutrons in the nuclear of the atom.

The atomic number (Z) is equal to the number of protons.
Given protons = 19.
So, $Z = 19$.

The mass number (A) is the sum of protons and neutrons.
Given protons = 19, neutrons = 20.

Using the notation $^A_Z Y$:

The nucleus contains 19 protons and 20 neutrons.

For a neutral atom, the number of electrons equals the number of protons.
Number of electrons = 19.

The 19 electrons will be arranged in shells as follows:

• 1st shell: 2 electrons
• 2nd shell: 8 electrons
• 3rd shell: 8 electrons
• 4th shell: 1 electron (Total: $2+8+8+1 = 19$ electrons)

The atomic structure would be drawn as:

• A central nucleus containing "19 protons" and "20 neutrons".
• Four concentric circles (electron shells) around the nucleus.
• The first shell (closest to the nucleus) with 2 electrons.
• The second shell with 8 electrons.
• The third shell with 8 electrons.
• The fourth shell (outermost) with 1 electron.