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Atomic Structure and Periodic Table

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Question 1Question →

An isotope of a neutral atom has a mass number of 3131 and contains 1616 neutrons in its nucleus. If this atom gains 33 electrons to form a stable anion, what is the total number of subatomic particles (protons, neutrons, and electrons) in the resulting ion?

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Answer: 4949

Answer

The total number of subatomic particles in the resulting ion is 4949.
The atomic number is found by subtracting neutrons from the mass number (31−16=1531 - 16 = 15 protons). A neutral atom has 1515 electrons, and gaining 33 electrons increases the electron count to 1818. Adding 1515 protons, 1616 neutrons, and 1818 electrons gives a total of 4949 subatomic particles.

Step-by-Step Solution

1
Determine the number of protons in the atom.
1515 protons
The atomic number equals the mass number minus the number of neutrons: 31−16=1531 - 16 = 15.
2
Determine the number of electrons in the resulting anion.
1818 electrons
A neutral atom has equal numbers of protons and electrons (1515). Gaining 33 electrons yields 15+3=1815 + 3 = 18 electrons.
3
Sum all subatomic particles (protons, neutrons, and electrons) in the ion.
15+16+18=4915 + 16 + 18 = 49
The total particle count is the sum of 1515 protons, 1616 neutrons, and 1818 electrons.

Key Concept

Calculating subatomic particle totals in ions using mass number and charge
Estimated Time:1m 30s
Question 2Question →

A divalent metal cation (M2+M^{2+}) contains 1818 electrons. In the nucleus of this isotope, the number of neutrons is 44 greater than the number of protons. What is the mass number of this isotope?

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Answer: 44

Answer

The mass number of this isotope is 4444.
A neutral atom that forms a divalent cation (M2+M^{2+}) loses 22 electrons. Since the cation has 1818 electrons, the neutral atom has 2020 electrons and therefore 2020 protons. The isotope has 44 more neutrons than protons, giving 20+4=2420 + 4 = 24 neutrons. The mass number is the sum of protons and neutrons: 20+24=4420 + 24 = 44.

Step-by-Step Solution

1
Determine the atomic number (number of protons) from the cation's charge and electron configuration.
Protons = 2020
A divalent cation (M2+M^{2+}) has lost 22 electrons relative to its neutral state. The neutral atom therefore has 18+2=2018 + 2 = 20 electrons and, correspondingly, 2020 protons.
2
Calculate the total number of neutrons in the nucleus.
Neutrons = 2424
The problem specifies that the number of neutrons exceeds the number of protons by 44, giving 20+4=2420 + 4 = 24 neutrons.
3
Sum the protons and neutrons to obtain the mass number (AA).
Mass number = 4444
The mass number of an isotope is defined as the total number of nucleons (protons plus neutrons): 20+24=4420 + 24 = 44.

Key Concept

Calculation of atomic number and mass number from ionic charge and subatomic particle relationships.
Estimated Time:1m 30s
Question 3Question →

An isotope of an element has a mass number of 7979 and contains 4545 neutrons in its nucleus. If this neutral atom gains the minimum number of electrons required to achieve a stable octet in its outermost valence shell, what is the total number of subatomic particles (protons, neutrons, and electrons combined) in the resulting ion?

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Answer: 115115

Answer

115 total subatomic particles
The atomic number is determined by subtracting the number of neutrons from the mass number: 79−45=3479 - 45 = 34 protons. An element with 3434 protons has 66 valence electrons in its outer shell (configuration 2,8,18,62, 8, 18, 6) and requires 22 additional electrons to form a stable octet, resulting in 3636 electrons. The sum of all subatomic particles in the ion is 34 protons+45 neutrons+36 electrons=11534\text{ protons} + 45\text{ neutrons} + 36\text{ electrons} = 115.

Step-by-Step Solution

1
Calculate the atomic number (number of protons) of the neutral atom
Protons = 79−45=3479 - 45 = 34
The mass number (AA) equals the sum of protons (ZZ) and neutrons (NN), so Z=A−NZ = A - N.
2
Determine the number of valence electrons and electrons needed to achieve a stable octet
Valence electrons = 66; electrons to gain = 8−6=28 - 6 = 2
An element with atomic number 3434 has an electron configuration of 2,8,18,62, 8, 18, 6. It requires 22 additional electrons to fill its outer shell with 88 valence electrons.
3
Determine the total number of electrons in the resulting ion
Electrons = 34+2=3634 + 2 = 36
Gaining 22 electrons to form a stable 2−2- anion increases the electron count from 3434 to 3636.
4
Sum all subatomic particles (protons, neutrons, and electrons)
Total particles = 34+45+36=11534 + 45 + 36 = 115
The total particle count is the sum of protons (3434), neutrons (4545), and electrons (3636).

Key Concept

Calculating subatomic particle totals using mass number, neutron count, valence electron configurations, and ion formation.
Estimated Time:1m 30s
Question 4Question →

An atom of an unknown element forms a stable ion with a +3+3 charge. This specific ion contains 1010 electrons. If the mass number of a particular isotope of this element is equal to twice its atomic number plus one, how many neutrons does the nucleus of this isotope contain?

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Answer: 14

Answer

The isotope contains 14 neutrons.
To solve this, first find the atomic number. A +3+3 ion has lost 3 electrons. Since this ion has 10 electrons, the neutral atom must have 10+3=1310 + 3 = 13 protons (atomic number 13). Next, calculate the mass number using the provided formula: 2(13)+1=272(13) + 1 = 27. Finally, subtract the number of protons from the mass number to find the number of neutrons: 27−13=1427 - 13 = 14.

Step-by-Step Solution

1
Determine the atomic number (number of protons).
The atomic number is 13.
A +3+3 charge indicates the neutral atom lost 3 negatively charged electrons. Since the ion has 10 electrons, the neutral atom originally had 10+3=1310 + 3 = 13 electrons. The number of protons equals the number of electrons in a neutral atom.
2
Calculate the mass number.
The mass number is 27.
The problem states the mass number is twice the atomic number plus one: 2(13)+1=272(13) + 1 = 27.
3
Calculate the number of neutrons.
There are 14 neutrons.
The number of neutrons is found by subtracting the atomic number (protons) from the mass number: 27−13=1427 - 13 = 14.

Key Concept

Calculating subatomic particles for ions by first determining the true atomic number from the ion's charge and electron count, then utilizing mass number relationships.
Estimated Time:1m 30s
Question 5Question →

A neutral atom of fluorine has an atomic number of 99 and a mass number of 1919. How many neutrons are contained in the nucleus of this atom?

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Answer: 1010

Answer

The nucleus contains 1010 neutrons.
The mass number (A=19A = 19) is the total number of protons and neutrons in the nucleus. The atomic number (Z=9Z = 9) represents the number of protons. The number of neutrons is determined by subtracting the atomic number from the mass number: 19−9=1019 - 9 = 10.

Step-by-Step Solution

1
Identify the given atomic number and mass number.
Atomic number (ZZ) = 99, Mass number (AA) = 1919.
The atomic number indicates the number of protons, while the mass number represents the sum of protons and neutrons.
2
Apply the subatomic particle calculation formula: Number of Neutrons=Mass Number(A)−Atomic Number(Z)\text{Number of Neutrons} = \text{Mass Number} (A) - \text{Atomic Number} (Z).
19−9=1019 - 9 = 10
Subtracting the number of protons from the total nucleon count yields the number of neutrons.

Key Concept

Subatomic particle calculation using atomic number and mass number
Estimated Time:45s
Question 6Question →

Match each fundamental atomic structure term with its correct scientific definition.

Click a left item, then click its matching right item

Items

Atomic number (ZZ)
Mass number (AA)
Valence electrons
Isotopes

Matches

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Answer

Atomic number matches the number of protons defining element identity; Mass number matches the sum of protons and neutrons; Valence electrons match the outermost shell electrons involved in bonding; Isotopes match atoms of the same element with differing neutron counts.
Each scientific term corresponds directly to its foundational definition in atomic structure: atomic number represents protons; mass number represents protons plus neutrons; valence electrons are the outermost bonding electrons; isotopes are atoms of the same element varying in neutron number.

Step-by-Step Solution

1
Define atomic number (ZZ)
Identified as the count of protons in the nucleus, defining elemental identity.
By definition, the number of protons is unique to each element and equals its atomic number.
2
Define mass number (AA)
Identified as the sum of protons and neutrons.
Electrons have negligible mass, so the mass number accounts for the heavy nuclear particles.
3
Define valence electrons
Identified as outermost electrons governing bonding.
Only electrons in the outermost energy level participate in chemical reactions and bond formation.
4
Define isotopes
Identified as atoms of the same element with different neutron numbers.
Since proton number defines the element, isotopes share chemical properties but have different physical masses due to unequal neutrons.

Key Concept

Core definitions of subatomic particles, nuclear notation, and electron configurations in atomic theory.
Estimated Time:45s
Question 7Question →

A neutral atom of silicon contains 1414 protons and 1616 neutrons in its nucleus. What is the mass number of this silicon atom?

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Answer: 3030

Answer

The mass number of the silicon atom is 3030.
The mass number (AA) of an atom equals the total number of protons and neutrons located in its nucleus. For this silicon atom, adding 1414 protons and 1616 neutrons gives a mass number of 3030.

Step-by-Step Solution

1
Identify the given subatomic particles in the nucleus
Protons = 1414, Neutrons = 1616
The mass number depends entirely on the nucleons (protons and neutrons) residing in the nucleus.
2
Apply the mass number formula: Mass Number=Number of Protons+Number of Neutrons\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}
Mass Number=14+16=30\text{Mass Number} = 14 + 16 = 30
Adding protons and neutrons gives the total nucleon count, which defines the mass number.

Key Concept

Calculation of atomic mass number from protons and neutrons
Estimated Time:45s
Question 8Question →

An isotope of potassium has an atomic number of 1919 and a mass number of 3939. How many neutrons are present in the nucleus of this atom?

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Answer: 20

Answer

The nucleus of this potassium atom contains 2020 neutrons.
The mass number (3939) represents the combined count of protons and neutrons in the nucleus. Because the atomic number is 1919, the atom has 1919 protons. Subtracting the protons from the mass number yields 39−19=2039 - 19 = 20 neutrons.

Step-by-Step Solution

1
Identify the atomic number and mass number from the problem statement.
Atomic number Z=19Z = 19, Mass number A=39A = 39.
The atomic number indicates the number of protons (1919), and the mass number indicates the total number of nucleons (3939).
2
Subtract the atomic number from the mass number to calculate the number of neutrons.
N=39−19=20N = 39 - 19 = 20
The number of neutrons is determined by subtracting the number of protons from the mass number (N=A−ZN = A - Z).

Key Concept

Calculating subatomic particle counts in an isotope using the relationship between mass number, atomic number, and neutrons (N=A−ZN = A - Z).
Estimated Time:40s
Question 9Question →

An isotope of carbon has a mass number of 1414 and contains 88 neutrons in its nucleus. What is the atomic number of this carbon atom?

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Answer: 66

Answer

66
The atomic number represents the number of protons in an atom's nucleus. Since the mass number (1414) is the sum of protons and neutrons, subtracting the 88 neutrons from 1414 yields 66 protons, making the atomic number 66.

Step-by-Step Solution

1
Identify the relationship between mass number, atomic number, and neutrons.
Mass Number=Atomic Number (Protons)+Neutrons\text{Mass Number} = \text{Atomic Number (Protons)} + \text{Neutrons}
The mass number of an atom is defined as the total number of protons and neutrons in the nucleus.
2
Substitute the known values and solve for the atomic number.
Atomic Number=14−8=6\text{Atomic Number} = 14 - 8 = 6
Subtracting the 88 neutrons from the total mass number of 1414 gives the number of protons, which defines the atomic number.

Key Concept

Relationship between mass number, atomic number, and subatomic particles
Estimated Time:45s
Question 10Question →

An atom is composed of a central core and surrounding subatomic particles. Match each atomic structure component on the left with its defining physical property and role on the right.

Click a left item, then click its matching right item

Items

Proton
Neutron
Electron
Atomic nucleus

Matches

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Answer

Proton matches with the positively charged particle defining atomic number; Neutron matches with the neutral particle in the nucleus contributing to mass; Electron matches with the negatively charged particle orbiting outside the nucleus; Atomic nucleus matches with the dense central core containing nearly all atomic mass.
Each subatomic entity is matched according to its fundamental physical characteristics: protons are positively charged and determine atomic number; neutrons are uncharged nucleons that contribute to mass number; electrons are negative particles that orbit the nucleus; and the nucleus is the dense core where nearly all atomic mass is located.

Step-by-Step Solution

1
Identify the charge, location, and function of a proton
Protons are positively charged (+1+1) nucleons whose count equals the atomic number (ZZ).
Every unique chemical element is defined by its unique number of protons.
2
Identify the charge, location, and function of a neutron
Neutrons are neutral (00 charge) nucleons that contribute to the atom's total mass number (AA).
Neutrons provide nuclear stability and mass without affecting net nuclear charge.
3
Identify the charge, location, and function of an electron
Electrons are negatively charged (−1-1) particles located in electron shells surrounding the nucleus.
Electrons balance positive nuclear charge in neutral atoms and determine bonding behavior.
4
Identify the structural definition and mass distribution of the atomic nucleus
The atomic nucleus is the dense central region containing all protons and neutrons.
Because protons and neutrons are roughly 18361836 times more massive than electrons, nearly all mass is located at the center.

Key Concept

Subatomic particle properties, charges, and atomic architecture
Estimated Time:45s
Question 11Question →

A neutral atom of sodium has an atomic number of 1111 and a mass number of 2323. What is the total number of neutrons present in the nucleus of this atom?

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Answer: 1212

Answer

1212 neutrons
The mass number (2323) is the total count of protons and neutrons in the nucleus, and the atomic number (1111) is the number of protons. Subtracting the atomic number from the mass number (23−11=1223 - 11 = 12) yields the exact number of neutrons.

Step-by-Step Solution

1
Identify the number of protons and the total nucleon count from the given values.
Atomic number (ZZ) = 1111 (protons), Mass number (AA) = 2323 (protons + neutrons)
The atomic number defines the number of protons, whereas the mass number represents the sum of protons and neutrons in the nucleus.
2
Calculate the number of neutrons by subtracting the atomic number from the mass number.
Number of neutrons=23−11=12\text{Number of neutrons} = 23 - 11 = 12
Subtracting the proton count from the total mass number yields the quantity of neutrons.

Key Concept

The number of neutrons in an atom is calculated by subtracting the atomic number (number of protons) from the mass number (total protons and neutrons).
Estimated Time:35s
Question 12Question →

An uncharged atom of chlorine has 1717 electrons and 1818 neutrons in its structure. What is the mass number of this chlorine atom?

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Answer: 35

Answer

The mass number of the chlorine atom is 3535.
For an uncharged atom, the number of protons equals the number of electrons (1717). The mass number is the sum of protons and neutrons (17+18=3517 + 18 = 35).

Step-by-Step Solution

1
Determine the number of protons in the atom
1717 protons
In any electrically neutral atom, the number of positively charged protons is equal to the number of negatively charged electrons.
2
Add the number of protons and neutrons together
17+18=3517 + 18 = 35
The mass number (AA) of an atom is defined as the total number of protons plus neutrons located in its nucleus.

Key Concept

The mass number of an atom is the sum of its protons and neutrons. In a neutral atom, the number of protons equals the number of electrons.
Estimated Time:45s
Question 13Question →

In a science laboratory, a technician analyzes a sample of phosphorus represented by the isotope symbol 1531P^{31}_{15}\text{P}. What is the total number of neutrons contained in the nucleus of this phosphorus atom?

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Answer: 1616

Answer

1616 neutrons
In standard isotopic notation ZAX^{A}_{Z}\text{X}, the superscript (A=31A = 31) is the mass number, representing the combined number of protons and neutrons, while the subscript (Z=15Z = 15) is the atomic number, representing the number of protons. The number of neutrons is found by subtracting the atomic number from the mass number (31−15=1631 - 15 = 16).

Step-by-Step Solution

1
Identify the mass number (AA) and atomic number (ZZ) from the isotope notation 1531P^{31}_{15}\text{P}.
A=31A = 31 and Z=15Z = 15.
In standard isotope notation, the upper superscript represents the mass number (AA) and the lower subscript represents the atomic number (ZZ).
2
Calculate the number of neutrons using the relationship Neutrons=A−Z\text{Neutrons} = A - Z.
Neutrons=31−15=16\text{Neutrons} = 31 - 15 = 16.
The mass number equals the total number of protons and neutrons, while the atomic number equals the number of protons.

Key Concept

Calculating the number of neutrons in an atom using standard isotopic notation (A−ZA - Z).
Estimated Time:45s
Question 14Question →

During a mass spectrometry investigation, researchers identify an isotope of chromium with a mass number of 5252 and an atomic number of 2424. How many neutrons are contained in the nucleus of this chromium atom?

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Answer: 2828

Answer

2828 neutrons
The mass number (A=52A = 52) is the total number of protons and neutrons in the nucleus. The atomic number (Z=24Z = 24) indicates the number of protons. Subtracting the atomic number from the mass number (52−24=2852 - 24 = 28) gives the total number of neutrons.

Step-by-Step Solution

1
Identify the given atomic parameters
Mass number (AA) = 5252; Atomic number (ZZ) = 2424
The mass number represents the sum of protons and neutrons, while the atomic number represents the number of protons.
2
Apply the neutron calculation formula: Neutrons=A−Z\text{Neutrons} = A - Z
Neutrons=52−24=28\text{Neutrons} = 52 - 24 = 28
Subtracting the number of protons from the total nucleon count isolates the number of neutrons.

Key Concept

Subatomic Particle Relationships in Atomic Structure
Estimated Time:45s
Question 15Question →

A neutral isotope of zinc has a nucleus containing 3636 neutrons and has an overall mass number of 6666. During a chemical reaction, this atom forms a Zn2+\text{Zn}^{2+} cation by losing 22 electrons. Calculate the total number of electrons present in the Zn2+\text{Zn}^{2+} ion.

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Answer: 28

Answer

28 electrons
The mass number (6666) minus the number of neutrons (3636) gives an atomic number of 3030, which corresponds to 3030 protons. A neutral atom has 3030 electrons, and losing 22 electrons to become Zn2+\text{Zn}^{2+} leaves exactly 2828 electrons.

Step-by-Step Solution

1
Calculate the number of protons (atomic number) in the zinc atom
30 protons
The mass number equals the sum of protons and neutrons (A=Z+NA = Z + N), so Z=66−36=30Z = 66 - 36 = 30.
2
Calculate the remaining electrons in the Zn2+\text{Zn}^{2+} cation
28 electrons
A neutral atom has an equal number of protons and electrons (30). A +2+2 charge indicates the loss of 2 electrons (30−2=2830 - 2 = 28).

Key Concept

Subatomic particle counts in isotopes and monatomic ions
Estimated Time:1m 0s
Question 16Question →

A stable isotope of silicon has 1414 protons and a total mass number of 3030. How many neutrons are located inside its nucleus?

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Answer: 16

Answer

The nucleus contains 16 neutrons.
The number of neutrons in an atom is found by subtracting the atomic number (number of protons) from the mass number. For this silicon isotope with a mass number of 3030 and 1414 protons, the calculation is 30−14=1630 - 14 = 16 neutrons.

Step-by-Step Solution

1
Identify the given nuclear parameters.
Mass number (AA) = 3030; number of protons / atomic number (ZZ) = 1414.
The mass number represents the sum of protons and neutrons in the nucleus, while the number of protons defines the atomic number.
2
Apply the relationship N=A−ZN = A - Z to determine the number of neutrons.
N=30−14=16N = 30 - 14 = 16.
Subtracting the number of protons from the total mass number yields the number of neutrons.

Key Concept

Calculating Subatomic Particles in an Atom
Estimated Time:45s
Question 17Question →

An atom of bromine has an atomic number of 3535 and a mass number of 8181. What is the total number of neutrons contained in its nucleus?

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Answer: 4646

Answer

The nucleus contains 4646 neutrons.
The mass number of an atom is the total count of protons and neutrons in the nucleus (A=protons+neutronsA = \text{protons} + \text{neutrons}). Given that the atomic number is 3535 (protons = 3535) and the mass number is 8181, the number of neutrons is calculated as 81−35=4681 - 35 = 46.

Step-by-Step Solution

1
Identify the given values from the problem statement.
Atomic number (ZZ) = 3535 (which equals the number of protons); Mass number (AA) = 8181 (total nucleons in the nucleus).
The atomic number defines the number of protons, and the mass number represents the sum of protons and neutrons.
2
Apply the relationship between mass number, protons, and neutrons: Mass Number (A)=Protons (Z)+Neutrons (N)\text{Mass Number } (A) = \text{Protons } (Z) + \text{Neutrons } (N).
N=A−ZN = A - Z
To find the unknown number of neutrons, rearrange the standard subatomic relationship.
3
Substitute the known integer values into the equation: N=81−35N = 81 - 35.
N=46N = 46
Subtracting 3535 from 8181 gives the total number of neutrons in the nucleus.

Key Concept

The mass number (AA) of an atom equals the sum of its protons (ZZ) and neutrons (NN). The number of neutrons is found by subtracting the atomic number from the mass number (N=A−ZN = A - Z).
Estimated Time:45s
Question 18Question →

An ion with a +3+3 positive charge has 1010 electrons and a mass number of 2727. How many neutrons are located inside the nucleus of this ion?

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Answer: 14

Answer

14 neutrons
For any atom or ion, the mass number equals the total count of protons and neutrons in the nucleus. Because this ion has a +3+3 charge and 1010 electrons, it must contain 1313 protons (10+310 + 3). Subtracting 1313 protons from the mass number of 2727 gives exactly 1414 neutrons.

Step-by-Step Solution

1
Calculate the atomic number (number of protons) using the ion's charge and electron count.
The atom has 1313 protons.
A positive charge (+3+3) indicates that the atom has lost 33 electrons relative to its proton count. Therefore, Protons=Electrons+Charge=10+3=13\text{Protons} = \text{Electrons} + \text{Charge} = 10 + 3 = 13.
2
Calculate the number of neutrons using the mass number and the proton count.
The nucleus contains 1414 neutrons.
Mass number is the sum of protons and neutrons (A=Z+NA = Z + N). Thus, Neutrons=Mass Number−Protons=27−13=14\text{Neutrons} = \text{Mass Number} - \text{Protons} = 27 - 13 = 14.

Key Concept

Relationship between mass number, atomic number (protons), net ionic charge, and subatomic particle counts.
Estimated Time:1m 0s
Question 19Question →

A neutral phosphorus atom contains 1515 protons and 1616 neutrons. If this atom gains 33 electrons to form a stable phosphide ion, what is the mass number of the resulting ion?

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Answer: 31

Answer

The mass number of the resulting phosphide ion is 3131.
The mass number (AA) is defined as the total number of protons and neutrons located in the nucleus (15+16=3115 + 16 = 31). When an atom gains or loses electrons, it forms an ion with an electric charge, but the contents of the nucleus remain unchanged.

Step-by-Step Solution

1
Identify the components that determine the mass number of an atom or ion.
Mass number (AA) is calculated as the sum of protons (ZZ) and neutrons (NN).
Electrons have negligible mass relative to nucleons and reside outside the nucleus, so they are not included in the mass number.
2
Calculate the mass number using the given proton and neutron counts.
A=15+16=31A = 15 + 16 = 31
Adding 1515 protons and 1616 neutrons yields the total number of nucleons in the nucleus.
3
Evaluate the effect of gaining 33 electrons on the mass number.
The mass number remains 3131.
Gaining electrons changes only the net electric charge from 00 to −3-3, leaving the nucleus and mass number unaltered.

Key Concept

The mass number of an atom or ion is strictly the sum of its protons and neutrons (A=Z+NA = Z + N) and does not change during ionization.
Estimated Time:45s
Question 20Question →

Match each chemical species with its correct composition of protons, neutrons, and electrons.

Click a left item, then click its matching right item

Items

Neutral Carbon-12 atom (612C^{12}_{6}\text{C})
Sodium ion (1123Na+^{23}_{11}\text{Na}^{+})
Fluoride ion (919F−^{19}_{9}\text{F}^{-})
Neutral Neon-20 atom (1020Ne^{20}_{10}\text{Ne})

Matches

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Answer

Neutral Carbon-12 matches 6 protons, 6 neutrons, and 6 electrons; Sodium ion (+1) matches 11 protons, 12 neutrons, and 10 electrons; Fluoride ion (-1) matches 9 protons, 10 neutrons, and 10 electrons; Neutral Neon-20 matches 10 protons, 10 neutrons, and 10 electrons.
Each species is correctly matched by identifying protons from the atomic number (ZZ), computing neutrons by subtracting the atomic number from the mass number (A−ZA - Z), and adjusting the electron count according to the ionic charge (e−=Z−chargee^- = Z - \text{charge}).

Step-by-Step Solution

1
Determine the number of protons from the atomic number (ZZ) for each species.
Carbon has 66 protons, Sodium has 1111 protons, Fluorine has 99 protons, and Neon has 1010 protons.
The atomic number uniquely defines the identity of an element and equals the total proton count.
2
Calculate the number of neutrons using Neutrons=Mass Number (A)−Atomic Number (Z)\text{Neutrons} = \text{Mass Number } (A) - \text{Atomic Number } (Z).
Carbon-12 has 12−6=612 - 6 = 6 neutrons; Sodium-23 has 23−11=1223 - 11 = 12 neutrons; Fluorine-19 has 19−9=1019 - 9 = 10 neutrons; Neon-20 has 20−10=1020 - 10 = 10 neutrons.
Mass number is the sum of protons and neutrons in the nucleus.
3
Determine the electron count based on net charge using Electrons=Protons−Charge\text{Electrons} = \text{Protons} - \text{Charge}.
Neutral Carbon has 66 electrons; Na+\text{Na}^{+} has 11−(+1)=1011 - (+1) = 10 electrons; F−\text{F}^{-} has 9−(−1)=109 - (-1) = 10 electrons; neutral Neon has 1010 electrons.
Cations lose electrons to form positive charges, anions gain electrons to form negative charges, and neutral atoms have equal numbers of protons and electrons.

Key Concept

Subatomic particle calculations in neutral atoms and isoelectronic ions
Estimated Time:1m 0s
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