Exercises on organizing the Periodic Table

Correct alternative: d) the number of protons in the atomic nucleus.

The Periodic Table organizes the known chemical elements according to the number of protons in the nucleus of the atom, which corresponds to the atomic number of the element.

For example, sodium (Na) has atomic number 11 because in the nucleus of its atom there are 11 protons.

Correct alternative: b) the sublevel that the most energetic electron occupies.

In the Periodic Table the representative elements can be seen at the ends, which correspond to groups 1, 2, 13, 14, 15, 16, 17, 18. In representative elements the most energetic electron is located in the s or p sublevel.

Check the electronic distribution of the first element of each group classified as representative.

Group	element	eletronic distribution
Group 1	3read	1s^2 2s^1
Group 2	4be	1s^2 2s^2
group 13	5B	1s^2 2s^2 2P^1
Group 14	6Ç	1s^22s^22P^2
group 15	7N	1s^2 2s^22P^3
Group 16	8O	1s^2 2s^2 2P^4
Group 17	9F	1s^2 2s^2 2P^5
Group 18	2he	1s^2

In the transition elements that are in the center of the table, from groups 3 to 12, the most energetic electron is located in the d sublevel, being classified as the inner transition, or f, which corresponds to the outer transition, are the lanthanides and actinides located in two lines below the others. elements.

Correct alternative: c) similar properties.

By observing the similar physical and chemical properties of chemical elements, it was possible to group them into families on the periodic table. Today, IUPAC recommends that the grouping of elements, which correspond to the vertical lines of the table, be called a group.

These similar characteristics happen because the elements of the same group have the same number of valence electrons. See the example of group 1 or alkali metal family.

Group 1	Eletronic distribution
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

One of the main characteristics of this group is the ability of the elements to react with water and form hydroxides, such as LiOH and NaOH.

Correct alternative: c) C, H, O and N

a) WRONG. Although boron (B) and iodine (I) are not metals, vanadium (V) and potassium (k) are.

b) WRONG. Of these elements only argon (Ar) is not a metal. Cesium (Cs), barium (Ba) and aluminum (Al) are.

c) CORRECT. Carbon (C), hydrogen (H), oxygen (O) and nitrogen (N) are not metals. Although hydrogen is located on the left in the table, above lithium in group 1, it is not part of that group.

d) WRONG. Neon (Ne), xenon (Xe), germanium (Ge) are non-metals. Cerium (Ce) is a metal.

Correct alternative: c) in ascending order of atomic number.

Early attempts to group chemical elements were based on the mass of atoms. However, the current periodic table presents the elements in ascending order of atomic number.

Atomic radius and electronegativity are periodic properties, that is, they vary as the atomic number increases or decreases.

Correct alternative: c) horizontal lines correspond to periods and vertical lines are element families.

a) WRONG. The most complete table was created by Mendeleev, but it was Henry Monseley who reorganized the table proposed by mendeleev in ascending order of atomic number.

b) WRONG. Representative elements are located in s blocks, groups 1 and 2, and p block, groups 13 to 18.

c) CORRECT. The horizontal lines, from 1 to 7, are the periods of the periodic table and correspond to the number of filled or semi-filled energy levels. The 18 vertical lines are groups or families that bring together elements with similar properties.

d) WRONG. Most elements of the periodic table are metals and are located in the center and to the left.

I. alkali metals The. Be, Mg, Ca, Sr, Ba and Ra II. alkaline earth metals B. Li, Na, K, Rb, Cs and Fr III. Chalcogens ç. F, Cl, Br, I, At and Ts IV. Halogens d. He, Ne, Ar, Kr, Xe, Rn and Og V. Noble Gases and. O, S, Se, Te, Po and Lv

Correct alternative: d) I.b; II.a; III.e; IV.c; V.d

The correct association between families and elements on the periodic table is:

I.b. Alkali metals: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr).

II.a. Alkaline earth metals: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra).

III.e. Chalcogens: oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), livermory (Lv).

IV.c. Halogens: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At) and tenessine (Ts).

V.d. Noble Gases: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and oganeseson (Og).

Correct alternative: c) noble gas.

Performing the electronic distribution it is possible to know the location of an element in the periodic table. Since the atomic number of the element is 10, then it has 10 protons in the nucleus and therefore 10 electrons in the electrosphere.

1s² 2s² 2p⁶

Note that the ground state atom of the element has only two shells and the outermost shell has 8 electrons. Therefore, we can say that the element is a noble gas. Checking the periodic table we will find that it is the element neon (Ne).

Correct alternative: d) Halogens and noble gases.

Halogens have the ns configuration² np⁵ in the valence layer. Check out the examples:

Fluorine: ₉F: 1s² 2s² 2p⁵
Chlorine: ₁₇Cl: 1s² 2s² 2p⁶ 3s² 3p⁵

Noble gases, on the other hand, have the ns configuration² np⁶:

Neon: ₁₀Ne: 1s²2s² 2p⁶
Argon: ₁₈Air: 1s² 2s² 2p⁶3s² 3p⁶

The exception of this group is helium, which, as it has only 2 electrons, has the 1s configuration².

Answer: Magnesium (Mg), Calcium (Ca), Carbon (C), Nitrogen (N) and Argon (Ar).