Question

How many protons, electrons, and neutrons are in I- and Li+ ?

Answer 1

For I-
protons = atomic no. = 53
neutrons = atomic mass - atomic number = (127 - 53) = 74

Since it has a negative positive charge, to find the no. of electrons, we need to add 1 to the number of protons, i.e.
electrons = (53 + 1) = 54

And,
For, Li+

protons = atomic no. = 3
neutrons = atomic mass - atomic number = (7 - 3) = 4

Since it has a positive charge, to find the no. of electrons, we need to subtract 1 form the number of protons, i.e.
electrons = (3 - 1) = 2

Answer 2

These are two questions and two answers.

Question 1: protons, electrons, and neutrons in I⁻

Answer: 53 protons, 54 electrons, and a variable number of neutrons. One possibility is 74 neutrons, if it is the most stable isotope, iodine-127.

Explanation:

1) I⁻ is the anion of the atom I

2) One negative charge means that one electron has been added to the neutral atom of I.

3) The element I has atomic number 53 (you see this is a periodic table).

4) The atomic number 53 means that it has 53 protons.

5) The neutral atom has the same number of electrons than protons, i.e. 53. Since the anion I⁻ has one additional electron, it has 54 electrons.

6) The number of neutrons is not a fixed quantity. Different isotopes of the same element have different number of neutrons.

7) The isotope iodine-127, which is the only stable isotope of iodine has 74 neutrons.

The number of neutrons is calculated as the mass number (127) less the number of protons (53): 127 - 53 = 74.

Question 2: protons, electrons, and neutrons in Li⁺

Answer: 3 protons, 2 electrons, variable number of neutrons, may be 3 or 4 depending of the isotope.

Explanation:

1) Li⁺ is the cation of the atom Li

2) One positive charge means that one electron has been removed from the neutral atom of Li.

3) The element Li has atomic number 3 (you see this is a periodic table).

4) The atomic number 3 means that it has 3 protons.

5) The neutral atom has the same number of electrons than protons, i.e. 3. Since the anion Li has one less electron, it has 2 electrons.

6) The number of neutrons is not a fixed quantity. Different isotopes of the same element have different number of neutrons.

7) There are two natural stable isotopes of lithium.

The isotope lithium-7, has 4 neutrons, and the isotope lithium-6 has 3 neutrons.

The number of neutrons is calculated as the mass number less the number of protons (3):

i) 7 - 3 = 4

ii) 6 - 3 = 3