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Atomic Structure and Periodic Table

28 questions

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Question 21Question →

An atom of potassium has a mass number of 3939 and contains 2020 neutrons in its nucleus. When this atom forms a stable potassium ion (K+K^+) by losing one electron, what is the total number of subatomic particles (protons, neutrons, and electrons) present in the ion?

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Answer: 5757

Answer

The potassium ion contains a total of 5757 subatomic particles.
The correct answer is 5757. The number of protons is found by subtracting the neutron count from the mass number (39−20=1939 - 20 = 19). Because the potassium ion carries a +1+1 charge (K+K^+), it has lost one electron, leaving 1818 electrons. Adding all subatomic constituents gives 19 protons+20 neutrons+18 electrons=57 total particles19\text{ protons} + 20\text{ neutrons} + 18\text{ electrons} = 57\text{ total particles}.

Step-by-Step Solution

1
Calculate the number of protons in the potassium atom.
Protons = 39−20=1939 - 20 = 19
The mass number (AA) is the sum of protons (ZZ) and neutrons (NN), so Z=A−NZ = A - N.
2
Determine the number of electrons in the K+K^+ ion.
Electrons = 19−1=1819 - 1 = 18
A neutral potassium atom has 1919 electrons; forming a +1+1 cation requires losing 11 electron.
3
Sum the total number of protons, neutrons, and electrons.
Total particles = 19+20+18=5719 + 20 + 18 = 57
The question requests the combined count of all subatomic particles in the ion.

Key Concept

Subatomic particle calculations in atomic structure and ions
Estimated Time:1m 0s
Question 22Question →

An isotope of an alkaline earth metal located in Period 4 (Group 2) of the periodic table contains 2424 neutrons in its nucleus. What is the mass number of this neutral isotope?

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Answer: 44

Answer

44
An element in Group 2 and Period 4 of the periodic table is calcium (Ca\text{Ca}), which has an atomic number of 2020. This means every calcium atom contains 2020 protons in its nucleus. The mass number of an isotope is the total number of protons and neutrons combined: 20 protons+24 neutrons=4420\text{ protons} + 24\text{ neutrons} = 44.

Step-by-Step Solution

1
Determine the atomic number of the element using its periodic table position.
Atomic number is 2020 (contains 2020 protons).
The alkaline earth metal (Group 2) in Period 4 is calcium (Ca\text{Ca}), which has an atomic number of 2020.
2
Calculate the mass number by summing the number of protons and neutrons.
Mass number=20+24=44\text{Mass number} = 20 + 24 = 44.
The mass number (AA) is defined as the total count of nucleons (protons plus neutrons) in the nucleus.

Key Concept

Determining mass number from periodic table position and subatomic particle counts
Estimated Time:1m 0s
Question 23Question →

A neutral atom has 22 electrons in its first energy level, 88 electrons in its second energy level, and 66 valence electrons in its third energy level. If the mass number of this atom is 3434, what is the total number of neutrons located in its nucleus?

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Answer: 1818

Answer

1818 neutrons
In a neutral atom, the total number of electrons equals the number of protons (atomic number, ZZ). Summing the electrons across all three energy levels (2+8+62 + 8 + 6) yields 1616 electrons, which means the nucleus contains 1616 protons. Because mass number (AA) is the sum of protons and neutrons (A=Z+NA = Z + N), the number of neutrons is found by subtracting the protons from the mass number: 34−16=1834 - 16 = 18.

Step-by-Step Solution

1
Calculate the total number of electrons in the neutral atom by summing all energy levels.
2+8+6=162 + 8 + 6 = 16 electrons
The total electron count is the sum of electrons distributed across the inner shells and the valence shell.
2
Determine the atomic number (number of protons) from the electron count.
Atomic number (ZZ) = 1616 protons
In any neutral atom, the number of positively charged protons equals the number of negatively charged electrons.
3
Calculate the number of neutrons by subtracting the atomic number from the mass number.
Number of neutrons = 34−16=1834 - 16 = 18
Mass number (AA) equals protons (ZZ) plus neutrons (NN), so N=A−ZN = A - Z.

Key Concept

Subatomic particle relationships and electron configuration in neutral atoms
Estimated Time:1m 0s
Question 24Question →

Elements in the periodic table are organized into families based on their shared subatomic properties, valence electron arrangements, and chemical reactivity. Match each chemical family on the left with its defining valence electron configuration and ionization behavior on the right.

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Items

Alkali Metals (Group 1)
Alkaline Earth Metals (Group 2)
Halogens (Group 17)
Noble Gases (Group 18)

Matches

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Answer

Alkali Metals pair with the single valence electron (ns1ns^1) forming +1+1 cations; Alkaline Earth Metals pair with two valence electrons (ns2ns^2) forming +2+2 cations; Halogens pair with seven valence electrons (ns2np5ns^2 np^5) forming −1-1 anions; Noble Gases pair with the filled valence octet (ns2np6ns^2 np^6) displaying high ionization energy and chemical inertness.
Each periodic family possesses a distinct valence electron configuration that dictates its chemical reactivity and ionic charges. Group 1 alkali metals possess one outer ss electron which they lose to form +1+1 cations. Group 2 alkaline earth metals possess two outer ss electrons and form +2+2 cations. Group 17 halogens possess seven valence electrons and gain one electron to form −1-1 anions. Group 18 noble gases have full outer electron shells, rendering them inert with exceptionally high ionization energies.

Step-by-Step Solution

1
Analyze the valence configuration and ion formation of Group 1 (Alkali Metals).
Group 1 elements have 11 valence electron in the outermost ss-orbital (ns1ns^1), leading to low first ionization energy and +1+1 cation formation.
Matching requires identifying the subatomic electron configuration unique to Group 1.
2
Analyze the valence configuration and ion formation of Group 2 (Alkaline Earth Metals).
Group 2 elements have 22 valence electrons in the outermost ss-orbital (ns2ns^2), forming +2+2 cations.
Differentiating Group 2 from Group 1 based on the number of valence electrons lost.
3
Analyze the valence configuration and ion formation of Group 17 (Halogens).
Group 17 nonmetals have 77 valence electrons (ns2np5ns^2 np^5), requiring one electron to complete an octet and forming −1-1 anions.
Halogens seek to achieve a noble gas configuration by gaining one electron.
4
Analyze the valence configuration and chemical properties of Group 18 (Noble Gases).
Group 18 elements possess complete valence shells (ns2np6ns^2 np^6), making them chemically unreactive with very high ionization energies.
Filled valence shells confer maximal stability and chemical inertness.

Key Concept

Periodic table family trends, valence electron configurations, and resulting ionic behavior.
Estimated Time:1m 30s
Question 25Question →

The periodic table organizes chemical elements into vertical columns known as groups or families, where members share similar valence electron configurations and chemical behaviors. Match each periodic table group on the left with its defining chemical characteristic on the right.

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Items

Alkali Metals (Group 1)
Alkaline Earth Metals (Group 2)
Halogens (Group 17)
Noble Gases (Group 18)

Matches

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Answer

Alkali Metals match with having 1 valence electron and reacting vigorously with water; Alkaline Earth Metals match with having 2 valence electrons and forming +2+2 cations; Halogens match with having 7 valence electrons and forming salts; Noble Gases match with possessing a complete valence shell and extreme chemical inertness.
The periodic table organizes elements by valence electron configurations. Group 1 elements (Alkali Metals) have 1 valence electron and react vigorously with water. Group 2 elements (Alkaline Earth Metals) have 2 valence electrons and form +2+2 cations. Group 17 elements (Halogens) have 7 valence electrons and readily gain an electron to form salts. Group 18 elements (Noble Gases) have complete valence shells, making them chemically inert.

Step-by-Step Solution

1
Determine valence electron count and characteristic reactivity for Group 1 elements.
Group 1 elements (Alkali Metals) have 1 valence electron and react violently with water.
The single outermost electron is readily lost, forming +1+1 cations.
2
Determine valence electron count and ion formation for Group 2 elements.
Group 2 elements (Alkaline Earth Metals) have 2 valence electrons and form +2+2 cations.
Losing two electrons achieves a stable preceding noble gas electron configuration.
3
Determine valence electron count and bonding behavior for Group 17 elements.
Group 17 elements (Halogens) have 7 valence electrons and readily gain 1 electron to form salts.
Gaining a single electron completes the outer valence octet.
4
Determine valence shell status and reactivity for Group 18 elements.
Group 18 elements (Noble Gases) possess full outer electron shells and are chemically inert.
A full complement of valence electrons provides maximum thermodynamic and chemical stability.

Key Concept

Periodic Table Groups and Valence Electron Trends
Question 26Question →

An isotope of titanium has a mass number of 4848 and contains 2626 neutrons in its nucleus. How many electrons surround the nucleus of a neutral atom of this isotope?

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Answer: 2222

Answer

A neutral atom of this titanium isotope has 2222 electrons.
The mass number (A=48A = 48) is the total count of protons and neutrons in the nucleus. Subtracting the 2626 neutrons from the mass number gives 2222 protons (48−26=2248 - 26 = 22). In a neutral atom, the number of electrons equals the number of protons, meaning there are 2222 electrons orbiting the nucleus.

Step-by-Step Solution

1
Calculate the number of protons in the nucleus using the mass number and neutron count
Number of protons =48−26=22= 48 - 26 = 22
The mass number (AA) equals the sum of protons (ZZ) and neutrons (NN), so Z=A−NZ = A - N.
2
Determine the number of electrons in the electrically neutral atom
Number of electrons =22= 22
In any neutral atom, the number of negatively charged electrons equals the number of positively charged protons.

Key Concept

Relationship between mass number, subatomic particles, and atomic neutrality
Estimated Time:45s
Question 27Question →

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

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Items

Atomic number
Mass number
Isotopes
Valence electrons

Matches

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Answer

Atomic number pairs with the proton quantity determining elemental identity; Mass number pairs with the sum of protons and neutrons; Isotopes pair with atoms having identical protons but different neutrons; Valence electrons pair with outermost electrons governing chemical reactivity.
Each term accurately describes a foundational property of atomic architecture: the atomic number corresponds strictly to proton count, mass number equals protons plus neutrons, isotopes are variants differing in neutron count, and valence electrons occupy the outermost shell to drive chemical behavior.

Step-by-Step Solution

1
Identify the definition of atomic number
Matched with the number of protons that defines the element (ZZ)
Every neutral or ionized atom of an element always contains the same characteristic number of protons.
2
Identify the definition of mass number
Matched with the sum of nuclear particles (protons + neutrons)
Electrons have negligible mass compared to nucleons, so atomic mass number is the total count of protons and neutrons.
3
Identify the definition of isotopes
Matched with atoms of the same element containing differing neutron quantities
Because atomic number remains constant for a given element, variations in atomic mass within an element arise solely from neutron count.
4
Identify the definition of valence electrons
Matched with the outermost electrons governing bonding behavior
The electron configuration in the highest energy level dictates how an atom interacts and shares or transfers electrons during reactions.

Key Concept

Core atomic structure parameters, subatomic particle arrangements, and isotopic terminology
Estimated Time:1m 0s
Question 28Question →

Elements in the periodic table are organized into families based on recurring valence electron configurations and characteristic chemical properties. Match each periodic table group on the left with its defining valence configuration and reactivity property on the right.

Click a left item, then click its matching right item

Items

Alkali metals (Group 1)
Alkaline earth metals (Group 2)
Halogens (Group 17)
Noble gases (Group 18)

Matches

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Answer

Alkali metals (Group 1) match with having 11 valence electron and forming +1+1 cations; Alkaline earth metals (Group 2) match with having 22 valence electrons and forming +2+2 cations; Halogens (Group 17) match with having 77 valence electrons and forming −1-1 anions; Noble gases (Group 18) match with having a complete outer electron shell and being chemically inert.
Each chemical family's behavior is dictated by its valence electron configuration: Group 1 has 11 valence electron forming +1+1 ions; Group 2 has 22 valence electrons forming +2+2 ions; Group 17 has 77 valence electrons gaining 11 electron to form −1-1 ions; Group 18 has complete outer shells resulting in chemical inertness.

Step-by-Step Solution

1
Identify the valence electron count and typical ion formation for Group 1 (Alkali metals).
Group 1 elements have 11 valence electron and lose it easily to form +1+1 cations.
Losing 11 electron gives alkali metals the stable electron configuration of the preceding noble gas.
2
Identify the valence electron count and typical ion formation for Group 2 (Alkaline earth metals).
Group 2 elements have 22 valence electrons and lose them to form +2+2 cations.
Losing both valence electrons achieves a stable outer octet.
3
Identify the valence electron count and typical ion formation for Group 17 (Halogens).
Group 17 elements have 77 valence electrons and gain 11 electron to form −1-1 anions.
Nonmetals with 77 valence electrons require only 11 additional electron to reach a full octet.
4
Identify the outer shell characteristics and reactivity of Group 18 (Noble gases).
Group 18 elements have completely filled valence shells and are non-reactive (inert).
A filled outer shell provides maximum thermodynamic stability without sharing, gaining, or losing electrons.

Key Concept

Periodic table groups reflect valence electron numbers that determine characteristic chemical properties and predictable ion formation.
Estimated Time:1m 0s
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