Exercises on the Periodic Table

The periodic table is an important study tool that gathers information about all known chemical elements.

Test your knowledge with this list of 17 questions with the different approaches on the subject and solve your doubts with the resolutions commented after the feedback.

To help understand the questions, use the periodic table complete and updated.

Periodic Table Organization

question 1

(UFU) In the early nineteenth century, with the discovery and isolation of various chemical elements, it became necessary to classify them rationally, in order to carry out systematic studies. Many contributions were added until reaching the current periodic classification of chemical elements. Regarding the current periodic classification, answer:

a) How are the elements listed sequentially in the periodic table?

See Answer

The periodic table is organized into sequences of chemical elements in ascending order of atomic number. This number corresponds to the number of protons in the nucleus of the atom.

This method of organization was proposed by Henry Moseley when he reconfigured the table proposed by Dmitri Mendeleiev.

An element can be located in the table by the family and period in which it is inserted. This distribution occurs as follows:

groups or families	18 vertical sequences
Groups of elements that have similar characteristics.

Periods	7 horizontal sequences
Number of electronic layers that the element has.

b) Which groups in the periodic table can be found: a halogen, an alkali metal, an alkaline earth metal, a chalcogen and a noble gas?

See Answer

The classification of elements into groups is done according to properties. Elements that are in the same group have similar characteristics and for the classifications given we have to:

Classification	Group	Family	Elements
halogen	17	7A	F, Cl, Br, I, At and Ts
alkali metal	1	1A	Li, Na, K, Rb, Cs and Fr
alkaline earth metal	2	2A	Be, Mg, Ca, Sr, Ba and Ra
chalcogen	16	6A	O, S, Se, Te, Po and Lv
noble gas	18	8A	He, Ne, Ar, Kr, Xe, Rn and Og

question 2

(PUC-SP) Resolve the issue based on the analysis of the statements below.

I – The current modern periodic table is arranged in ascending order of atomic mass.
II - All elements that have 1 electron and 2 electrons in the valence shell are, respectively, alkali metals and alkaline earth metals, provided that the principal quantum number of this layer (n 1).
III – In the same period, the elements present the same number of levels (layers).
IV – In the same group (family), the elements have the same number of levels (layers).

It is concluded that, with respect to the current periodic table of chemical elements, they are correct:

a) I and IV (only).
b) I and II (only).
c) II and III (only).
d) II and IV (only).
e) III and IV (only).

See Answer

Correct alternative: c) II and III (only).

Analyzing each alternative we have to:

I – WRONG. The elements are arranged in ascending order of atomic number.

II – CORRECT. The electrons in the valence shell define the group the element is located in.

alkali metals	1 electron in the valence shell
3read	2-1
11At	2-8-1
19K	2-8-8-1
37Rb	2-8-18-8-1
55Cs	2-8-18-18-8-1
87Fr	2-8-18-32-18-8-1

alkaline earth metals	2 electrons in the valence shell
4be	2-2
12mg	2-8-2
20Here	2-8-8-2
38Mr	2-8-18-8-2
56Ba	2-8-18-18-8-2
88Frog	2-8-18-32-18-8-2

The main quantum number corresponds to the shell in which the electron is located, being different from 1 because by the electronic distribution we notice that the location of the electron is from the second shell or n=2.

III – CORRECT. The location of an element in a certain period is due to the number of layers when making the electronic distribution.

Periods	7 horizontal sequences
1st period	1 layer: K
2nd period	2 layers: K, L
3rd period	3 layers: K, L, M
4th period	4 layers: K, L, M, N
5th period	5 layers: K, L, M, N, O
6th period	6 layers: K, L, M, N, O, P
7th period	7 layers: K, L, M, N, O, P, Q

Example: chemical element located in the second period.

IV – WRONG. Elements belonging to the same group have similar characteristics and this is due to the fact that they have the same number of electrons in the valence shell.

Example:

Beryllium	Magnesium
2 electrons in valence layer.	2 electrons in valence layer.

Therefore, beryllium and magnesium are part of group 2 of the Periodic Table.

question 3

(Unitins) Regarding the modern periodic classification of elements, identify the true statement:

a) in a family, the elements generally have the same number of electrons in the last shell.
b) on the periodic table, the chemical elements are placed in descending order of atomic masses.
c) in a family, the elements have very different chemical properties.
d) in one period, the elements have similar chemical properties.
e) all representative elements belong to group B of the periodic table.

See Answer

Correct alternative: a) in a family, the elements generally have the same number of electrons in the last shell.

a) CORRECT. Chemical elements of the same family have the same number of electrons in the last shell and this makes them have similar characteristics.

b) WRONG. Atomic masses increase as the atomic number of the element increases.

c) WRONG. The chemical properties of the elements are similar, so they are grouped in the same family.

d) WRONG. At one time, the elements have their electrons distributed in the same number of shells.

e) WRONG. The representative elements belong to group A, which corresponds to the families: 1A, 2A, 3A, 4A, 5A, 6A, 7A and 8A. Elements belonging to group B are transition elements.

question 4

(Vunesp) Considering the properties of chemical elements and the periodic table, it is incorrect to state:

a) a metal is a substance that conducts electrical current, is ductile and malleable.
b) a non-metal is a substance that does not conduct electrical current, is neither ductile nor malleable.
c) a semimetal has the physical appearance of a metal, but chemical behavior similar to that of a non-metal.
d) most chemical elements are made up of non-metals.
e) the noble gases are monoatomic.

See Answer

Incorrect alternative: d) most chemical elements are non-metals.

Note the classification of chemical elements on the periodic table into metals, nonmetals, and semimetals.

As we can see, most elements are metals.

a) CORRECT. Metals conduct electricity because of the electron clouds formed by free electrons, which are characteristic of their structure. They are ductile because they can turn into wires or sheets, depending on the region where pressure is applied. They are also malleable, as very thin sheets can be produced with this type of material.

b) CORRECT. Nonmetals have the opposite characteristics of metals. Instead of conductors, they are good thermal insulators and, as they are brittle, they are not molded into wires or sheets as they do not have good ductility and malleability.

c) CORRECT. Semimetals have characteristics intermediate to metals and non-metals. Being semiconductors of electricity, they have a metallic sheen but are brittle like non-metals.

d) WRONG. Most elements are classified as metals. The classes of metals present in the periodic table are: alkaline, alkaline earth, transitional internal and external.

e) CORRECT. Noble gases are monoatomic, so they are represented only by their initials.

Example:

noble gas	chalcogen
Helium (He)	Oxygen (O2)
monoatomic: formed by an atom	diatomic: formed by two atoms

Due to the stability of noble gases, the elements of this family have low reactivity and are also known as inert.

question 5

About the organization of the current Periodic Table, answer:

a) What are columns?
b) What are the lines?
c) What is the method used to organize the chemical elements?

See Answer

Answers:

a) the columns are the groups of the Periodic Table, formerly called families, that bring together chemical elements with similar properties.

b) The lines are the periods of the Periodic Table and indicate the number of electronic layers of an atom in the ground state.

c) The chemical elements in the current Periodic Table are arranged in ascending order of atomic number, which indicates the number of protons in the nucleus of the atom.

Periodic Table Families

question 1

(CESGRANRIO) Making the association between the columns below, which correspond to the element families according to the periodic table, the numerical sequence will be:

1. noble gases	• Group 1A
2. alkali metals	• Group 2A
3. alkaline earth metals	• Group 6A
4. Chalcogens	• Group 7A
5. Halogens	• Group 0

a) 1, 2, 3, 4, 5.
b) 2, 3, 4, 5, 1.
c) 3, 2, 5, 4, 1.
d) 3, 2, 4, 5, 1.
e) 5, 2, 4, 3, 1.

See Answer

Correct alternative: b) 2, 3, 4, 5, 1.

groups	electronic configuration
• Group 1A: 2. alkali metals	us^1 (with n1)
• Group 2A: 3. alkaline earth metals	us^2 (with n1)
• Group 6A: 4. Chalcogens	us^2np^4
• Group 7A: 5. Halogens	us^2np^5
• Group 0: 1. noble gases	1s^2 (He) or us^2np^6 (if n > 1)

question 2

(UECE) The chemical element with Z = 54 has in its valence layer the 5s configuration² 5p⁶. The elements with Z = 52 and with Z = 56 belong to the families of:

a) chalcogens and alkaline earth
b) halogens and alkalis
c) halogens and alkaline earth
d) chalcogens and alkalis

See Answer

Correct alternative: a) chalcogens and alkaline earths.

Given the atomic numbers, we performed the electronic distribution and found the following results:

54X and	52You	56Ba
8 electrons in valence layer	6 electrons in valence layer	2 electrons in valence layer
Noble Gases: 8A family	Chalcogens: 6A family	Alkaline Earth: family 2A

question 3

(F. Ibero-Americana-SP) The Periodic Table group that is characterized by the predominance of artificial elements is the following:

a) lanthanides
b) noble gases
c) transition metals
d) alkaline earth metals
e) actinides

See Answer

Correct alternative: e) actinides.

Artificial elements are those that do not exist in nature and that have been synthesized in the laboratory through nuclear reactions.

They are also called transuranic elements, as these radioactive elements have an atomic number greater than 92, which corresponds to uranium.

In general, these elements are short-lived, lasting up to fractions of a second.

According to this information we have to:

The elements found in nature are: lanthanides, noble gases, transition metals and alkaline earth metals. With the exception of technetium and promethium, which are artificial.

The predominance of artificial elements is actinides, classified as internal transition metals and inserted in the periodic table below the lanthanides. From that series, only actinium, thorium, protactinium and uranium are natural.

question 4

(U. Catholic Church of Salvador-BA) The X species^2- with 8 electrons in the outermost shell (valence shell) it can be from element X, which, in the Periodic Table, belongs to the group:

a) 7A
b) 6A
c) 2A
d) 1A
e) 8A

See Answer

Correct alternative: b) 6A.

According to the octet rule, for an element to acquire stability, it assumes the electronic configuration of a noble gas, which has 8 electrons in the valence shell.

Charge 2- on species X^2- indicates that the element has gained 2 electrons.

The electron configuration of the species having 8 electrons in the outermost shell is ns²np⁶.

Upon losing two electrons, the element returns to its ground state with ns electron configuration²np⁴.

The 6 electrons in the valence shell are characteristic of chalcogens, elements of the 6A family.

For example:

Element: oxygen	electronic configuration
8O	1s^22s^22p^4
species O^2-	1s^22s^22p^6

Learn more about Periodic Table Families.

Chemical elements

question 1

(CESGRANRIO) Given the elements of atomic numbers 3, 9, 11, 12, 20, 37, 38, 47, 55, 56 and 75, the option that only contains alkali metals is:

a) 3, 11, 37 and 55
b) 3, 9, 37 and 55
c) 9, 11, 38 and 55
d) 12, 20, 38 and 56
e) 12, 37, 47 and 75

See Answer

Correct alternative: a) 3, 11, 37 and 55

Alkali metals correspond to the chemical elements that end the electronic distribution with an electron in the s sublevel.

Making the electronic distribution of the given atomic numbers, we have the following alkali metals:

Z = 3	Z = 11	Z = 37	Z = 55
Lithium	Sodium	Rubidium	Cesium

The other atomic numbers correspond to elements of the following groups:

Alkaline earth metals: terminate electronic distribution at sublevel s².

Z = 12	Z = 38	Z = 56
Magnesium	Strontium	Barium

Transition metals: terminate electronic distribution at sublevel d.

Z = 30	Z = 47	Z = 75
Zinc	Silver	Rhenium

Halogens: terminate electronic distribution at sublevel p⁵.

Z = 9

question 2

(Unirio) “The artificial heart placed in Eloi began to be developed four years ago in the United States and is already used by around 500 people. The set, called the Heartmate, is made up of three main pieces. The most important is a four-pound round bag, 12 centimeters in diameter and 3 centimeters thick, made of titanium — a silver-white metal, light and strong.” _{Veja Magazine, July 1999.}

Among the metals below, the one that has, in the last layer, a number of electrons equal to that of titanium is:

a) C
b) In
c) Ga
d) Mg
e) Xe

See Answer

Correct alternative: d) Mg.

Titanium	electronic configuration	Layer distribution
22You	1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2	2, 8, 10, 2

From the electronic distribution of titanium, we see that this element has 2 electrons in the last shell.

Element	electronic configuration	Layer distribution
6Ç	1s^2 2s^2 2p^2	2, 4
11At	1s^2 2s^2 2p^6 3s^1	2, 8, 1
31Ga	1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^104p^1	2, 8, 18, 3
12mg	1s^2 2s^2 2p^6 3s^2	2, 8, 2
54X and	1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6 4d^10 5s^2 5p^6	2, 8, 18, 18, 8

The element that also has 2 electrons in the last shell is magnesium.

question 3

(UFPA) Consider a certain chemical element whose most energetic sublevel is 5s². Its atomic number and the group in which it is located on the Periodic Table are, respectively:

a) 20; 1A
b) 20; 2A
c) 38; 2A
d) 38; 1A
e) 39; 2A

See Answer

Correct alternative: c) 38; 2A

By doing electronic distribution, we found that:

• The chemical element is located in the family 2A, as it has the most energetic sublevel the s²
• Has atomic number 38, which corresponds to the total number of electrons distributed.
• It is located in the fifth period, as the electronic distribution was carried out up to the fifth layer.

Checking this information in the Periodic Table, we can confirm that it is the element strontium.

question 4

(UFC) An x atom has one more proton than a y atom. Based on this information, determine the correct statement.

a) If y is alkaline earth, x is alkali metal.
b) If y is a noble gas, x is a halogen.
c) If y is a transition metal, x is a noble gas.
d) If y is a noble gas, x is an alkali metal.
e) x is located in the same period before atom y in the periodic table.

See Answer

Correct alternative: d) If y is a noble gas, x is an alkali metal.

The periodic table is arranged in ascending order of atomic number.

If Y has atomic number z and X has one more proton than it, it means that these two elements are in the same period and X is subsequent to Y.

Example:

Element	subsequent element
zY	z + 1X
11At	12mg

The two elements are in the 3rd period and magnesium has one more proton than sodium.

According to this reasoning we have to:

a) WRONG. An alkali metal comes before an alkaline earth metal on the periodic table. The correct statement would be: If y is alkali metal, x is alkaline earth.

b) WRONG. A halogen comes before the noble gas on the periodic table. The correct statement would be: If y is halogen, x is noble gas.

c) WRONG. Transition metals and noble gases are separated by other chemical elements and therefore are not sequential.

d) CORRECT. Noble gases are the last group on the periodic table and alkali metals the first, so they are sequential.

Example:

noble gas	alkali metal
zY	z + 1X
2he	3read

Lithium, an alkali metal, has one more proton than helium, which is a noble gas.

e) WRONG. X is in the same period as Y but after it, not earlier as the alternative states.

question 5

From the atomic number of a chemical element it is possible to know:

a) the number of neutrons in the nucleus
b) the number of electrons in the electrosphere
c) the core mass

See Answer

Answer: b) the number of electrons in the electrosphere

An atom in the ground state is electrically neutral. So, knowing the atomic number, which corresponds to the number of protons (positively charged particles), we know the number of electrons (negatively charged particles) in the electrosphere.

For example, iron has atomic number 26, so in the ground state it has 26 electrons around the nucleus.

Learn more about chemical elements it's the atomic number.

Periodic and aperiodic properties

question 1

(UFSM) Judge whether the statements related to the periodic properties of the elements are true (T) or false (F).

( ) Depends on the atomic masses of the elements.
( ) They are repeated at more or less regular intervals in relation to the increase in atomic numbers.
( ) Are similar in the same group of elements.
( ) Are similar in the same period of elements.
( ) In the same group, the numerical values ​​of the periodic properties always increase when there is an increase in the atomic number of elements.

The correct sequence is:

a) V - F - V - F - F
b) V - F - F - V - V
c) F - V - V - F - F
d) F - V - F - V - V
e) V - F - F - V - F

See Answer

Correct alternative: c) F - V - V - F - F

(FALSE) Depend on the atomic masses of the elements.

According to Moseley's law of periodicity, many physical and chemical properties of chemical elements vary by atomic number.

(TRUE) They are repeated at more or less regular intervals in relation to the increase in atomic numbers.

Properties such as atomic radius, atomic volume, density, melting point, and boiling are examples of properties that recur regularly in the periodic table.

(TRUE) Are similar in the same group of elements.

The periodic table groups have been arranged with elements that have similar properties.

(FALSE) Are similar in the same period of elements.

Properties are similar in families, not periods. In periods, the elements are distributed by the number of electronic layers.

(FALSE) In the same group, the numerical values ​​of the periodic properties always increase when there is an increase in the atomic number of elements.

Properties can increase or decrease depending on the atomic number. An example of this is electronegativity, which decreases as the atomic number increases in a given group.

Read too: Periodic Properties

question 2

(FAESP) The aperiodic properties of the elements are:

a) density, atomic volume and atomic mass.
b) melting point, electronegativity and specific heat.
c) atomic volume, atomic mass and melting point.
d) atomic mass, specific heat and melting point.
e) atomic mass and specific heat.

See Answer

Correct alternative: e) atomic mass and specific heat.

The aperiodic properties are repeated at regular intervals.

Atomic mass is the measure of the atom's weight in atomic mass units, which corresponds to of the carbon-12 mass.

Specific heat determines the amount of heat needed to increase the temperature by 1 °C of 1 g of the element.

These two properties are unrelated to the element's position on the periodic table.

The other properties are classified as periodic as they increase or decrease with the atomic number. Are they:

• Density: represents the quotient between the mass and volume of an element.
• Atomic volume: represents the volume of a set of atoms and influences the distance between them.
• Melting point: temperature at which the transition from solid to liquid occurs.
• Electronegativity: the atom's ability to attract to itself the electronic pair it shares in a covalent bond.

Read too: electronegativity and Electronic Affinity

question 3

(PUC-PR) Among the following diagrams related to the periodic table, which ones are correct?

a) II and V
b) II and III
c) I and V
d) II and IV
e) III and IV

See Answer

Correct alternative: d) II and IV.

I. WRONG. Atom size variation is measured by the average distance from the nucleus to the outermost electron. The largest atoms are located at the bottom of the table, so the increase occurs according to the atomic number and the correct representation is:

II. CORRECT The energy required to rip an electron off an isolated atom in the gaseous state is called the ionization potential. It increases as shown in the statement diagram.

III. WRONG. Electronic affinity expresses the energy released when a neutral atom in the gaseous state receives an electron, which is a very important property of non-metals. The highest electronic affinities are observed in halogens and oxygen.

IV. CORRECT Electronegativity is related to ionization potential and electron affinity. As such, halogens are the most electronegative elements on the periodic table.

V. WRONG. Electropositivity occurs in the opposite direction to electronegativity. It represents the atom's ability to give up electrons.

Therefore, alkali metals have the highest electropositivity.

Keep testing your knowledge with the lists:

• Exercises on chemical bonds
• Exercises on electronic distribution
• Exercises on atomic models
• Exercises on thermochemistry

Understand the Periodic Table in 10 minutes