Question

selenium-50 selenium-55

of protons

of neutrons

of electrons

sodium-12 sodium-20

of protons

of neutrons

of electrons

part iii. fill in the isotope names and any missing information on the chart. use your periodic table and the information provided. assume all atoms are neutral.

of protons 32

of neutrons 30 32

of electrons

of protons 25

of neutrons 17 15

of electrons

Explanation:

Step1: Find Sodium's proton count

From periodic table, sodium (Na) has atomic number 11, so protons = 11. For neutral atoms, electrons = protons = 11. Neutrons = mass number - protons.

• Sodium-12: Neutrons = $12 - 11 = 1$
• Sodium-20: Neutrons = $20 - 11 = 9$

Step2: Find Selenium's proton count

Selenium (Se) has atomic number 34, so protons = 34. For neutral atoms, electrons = 34. Neutrons = mass number - protons.

• Selenium-50: Neutrons = $50 - 34 = 16$
• Selenium-55: Neutrons = $55 - 34 = 21$

Step3: Solve middle Se isotope table

First column: Protons=32 (germanium, Ge), neutrons=30, mass number = $32 + 30 = 62$, so isotope is Germanium-62. Electrons=32 (neutral atom).
Second column: Protons=32, neutrons=32, mass number = $32 + 32 = 64$, so isotope is Germanium-64. Electrons=32.

Step4: Solve bottom manganese table

First column: Protons=25 (manganese, Mn), neutrons=17, mass number = $25 + 17 = 42$, isotope is Manganese-42. Electrons=25 (neutral atom).
Second column: Protons=25, neutrons=15, mass number = $25 + 15 = 40$, isotope is Manganese-40. Electrons=25.

Answer:

Sodium Table

	Sodium-12	Sodium-20
# of neutrons	1	9
# of electrons	11	11

Selenium Table

	Selenium-50	Selenium-55
# of neutrons	16	21
# of electrons	34	34

Middle Isotope Table

	Germanium-62	Germanium-64
# of neutrons	30	32
# of electrons	32	32

Bottom Isotope Table

	Manganese-42	Manganese-40
# of neutrons	17	15
# of electrons	25	25