Additional tasks. Additional tasks are enhanced by the main properties

1. Which element has more pronounced metallic properties: a) beryllium or strontium; b) sodium or aluminum? Give a reasonable answer based on the position of the elements in the periodic table.

2. Give a description of element No. 16 according to the plan:

Position in the periodic table

Metal or non-metal

The structure of the atom

Electronic formula

The number of electrons on the outer energy level whether it is complete

Superior Oxide Formula

Does the element form a volatile compound with hydrogen, if so, what is its chemical formula

3. What is common and what are the differences in the structure of small and large periods? Show this on the example of the 3rd and 4th periods.

4. The element oxide has the composition EO 3 . Mass fraction oxygen in this oxide is 60%. What element forms an oxide?

Solutions and answers:

1. The metallic properties are more pronounced in a) strontium (from top to bottom, the metallic properties increase in groups), b) sodium (from left to right, the metallic properties weaken in groups).

3. Small periods consist of one row, large ones - of two rows, the properties of elements change strictly from metals to non-metals from left to right in any period.

1. What simple substance - formed by elements No. 11, No. 12 or No. 13 - has the most pronounced metallic properties? Why? Write the formulas for the hydroxides of these elements and indicate their character.

2. Indicate the most typical metal and non-metal of the 4th period. Justify the answer.
A typical metal of the fourth period is K, a non-metal is Kr (metallicity increases from right to left over the period). Typical metals contain 1-2 electrons at the external energy level (for potassium - 1), and non-metals more than 4 (for krypton - 8).

3. Which simple substance - formed by element No. 14, No. 15 or No. 16 - has the most pronounced non-metallic properties? Why? Write the formulas of the acids corresponding to higher oxides these elements.

4. An element with a constant valence of two is located in the 4th period. Its oxide and hydroxide are basic. What is this element? What is the structure of its atom? Write the formulas for the oxide and hydroxide of this chemical element.
Ca. The structure of an atom is 20 electrons, 20 protons, 20 neutrons. Core Charge +20. There are two electrons in the outer energy level. CaO is calcium oxide, Ca(OH)₂ is calcium hydroxide.

5. Indicate the serial number, nuclear charge and calculate the number of protons, neutrons and electrons in volumes: a) potassium (41K); b) beryllium (9Be); c) magnesium (24Mg); d) calcium (42Ca); e) aluminum (27Al); f) titanium (48Ti); g) vanadium (51V); h) iron (56Fe).

6. What is the difference between the composition of nuclei of isotopes: a) 63Cu and 65Cu; b) 107Ag and 109Ag? Give a reasonable answer based on the calculations.

7. Calculate molar masses substances whose formulas are ₂SO, NO₃, O. Write the formulas of similar compounds containing the isotope H and calculate their molar masses.

8. How many different mass molecules of sulfur oxide (IV) can be formed during the interaction of isotopes 16O, 17O, 18O and 32S? Write formulas for all molecules and calculate their molar masses.

9. Write electronic formulas atoms: a) sulfur and sodium; b) argon and potassium; c) calcium and chlorine; d) neon and aluminum; e) silicon and bromine; f) arsenic and carbon.

10. On the basis of the theory of the structure of atoms, explain the reasons for the periodicity of changes in the properties of elements and their compounds. Support your answer with specific examples.
Properties simple substances and compounds of elements are periodically repeated, because the electronic configurations of atoms are periodically repeated. So, for the atoms Be, Mg, Ca, Sr, Ba, the structure of the outer electron shell is the same, there are 2 electrons on it. These elements easily give them away, showing reducing properties and an oxidation state of +2.

11. How to explain, based on the theory of the structure of atoms, a sharp transition from inert gases to alkali metals?
In inert gases, the external energy level is complete, after the addition of one more electron to it, another energy level is filled, which becomes external. One electron in the outer energy level is a characteristic of alkali metals.

12. Determine the place of the elements in the periodic table according to the electronic formulas of their atoms: 1s2 2s2 2p6 3s2; 1s2 2s2 2p6 3s2 3p6; 1s2 2s2 2p6 3s2 3p6 4s2. Make formulas for oxides and hydroxides and acids corresponding to these elements.

13. Based on the position in the periodic table, characterize the elements potassium, bromine and aluminum.

14. The oxide of an element (metal of the 3rd period) has a molecular weight of 102. Determine the element and draw a diagram of the structure of its atom. Write the formulas for the oxide and hydroxide of this element and indicate their nature.

15. Calculate the mass (N.O.): a) 8.96 liters of a gaseous compound of fluorine with hydrogen; b) 13.44 liters of a gaseous compound of phosphorus with hydrogen; c) 17.92 liters of gaseous sulfur-hydrogen compounds.

16. Elements A and B belong to the same period. A simple substance formed by elements A reacts violently with water. A simple substance formed by element B is a heavy poisonous red-brown liquid with an unpleasant odor. What elements are we talking about?
Br - element B (Br₂ - heavy poisonous red-brown liquid). K - element A, reacts violently with water. Ca - also interacts with water, but not as violently as K.

17. Substance used as mineral fertilizer, consists of two elements - A and B. A simple substance corresponding to element A - alkali metal. Element A belongs to the same period as the element that forms the only non-metal that is liquid under ordinary conditions. Element B is in group VIIA, its atoms are part of table salt. Define elements A and B and write: a) electronic formulas of their atoms; b) the formula of the substance formed during their interaction.

18. Elements X and Y are in the 2nd period. A simple substance formed by element X reacts with water to release hydrogen. The molecular weight of the hydrogen compound of element Y is 20. Identify these elements and write: a) the electronic formulas of their atoms; b) the equation of interaction of simple substances formed by these elements; c) equation for the reaction of the hydroxide of element X with a volatile hydrogen compound of element Y.

19. What chemical properties has an element with atomic number 34? What element is it most similar in properties to? give a reasonable answer based on the position of the elements in the periodic table.

20. Find in the periodic table an element located in the 4th period, 5th row and showing a valency of six in combination with oxygen. What is its valence in combination with hydrogen? Write the formulas of these compounds.
Se. SeO₃ - selenium oxide (VI), H₂Se (valence of selenium in combination with hydrogen - II).

TEST FOR LESSON No. 2

« Periodic law and Periodic system of chemical elements D.I. Mendeleev. Radii of atoms, their periodic changes in the system of chemical elements. Patterns of changes in the chemical properties of elements and their compounds by periods and groups "

A1. Choose the answer that reveals the physical meaning of chemical periodicity. This is a periodic change:

configurations of valence electrons with an increase in the charge of atomic nuclei

atomic masses of elements with an increase in the charge of the nuclei of atoms

charges of atomic nuclei with increasing atomic masses elements

electronic configurations of atoms with increasing atomic radius

A2. The characteristic that matches the serial number of the element is:

relative atomic mass value

relative electronegativity value

number of electrons in an atom

number of neutrons in a nucleus

AZ. Select the characteristic indicated by the number of the period in which the element is located:

total number of electrons

atomic radius

total number of protons and neutrons

the number of energy levels in the electron shell of an atom

A4. Indicate the elements that are in the main subgroups of groups I and II of the Periodic system:

p-elements

s- and p-elements

s-elements

d-elements

A5. Specify chemical element, which has the largest atomic radius:
1) B 2) Li 3) Be 4) F

A6. Indicate the element of the third period, which most clearly exhibits non-metallic properties:
1) AI 2) S 3) CI 4) R

A7. Which chemical element has the smallest atomic radius?
1) Li 2) Cs 3) K 4) Na

A8. Indicate the characteristics of the element, in the nucleus of which there are 12 protons:

forms a hydrogen compound of type RH

has 10 electrons in its electron shell

located in the second period of the Periodic Table

located inIIAnd the group

A9. Select s-elements:

3) AI 4) Na

A10. For elements of the second period of the Periodic system with increasing serial number, the value of the atomic radius:

increases

changes periodically

decreases

remains constant

A11. In which row are the elements arranged in decreasing order of their atomic radius?
1) Li, Na, K 2) Au, Ag, Cu 3) C, F, O 4) CI, Br, I

A12. Select the type of oxides that form the elements of the main subgroup of group VI of the Periodic system:

acidic

main

amphoteric

non-salt-forming

A13. Indicate the nature of the change in the properties of oxides general formula R 2 O in the group from top to bottom:

acidic properties are enhanced

weaken amphoteric properties

the main properties are enhanced

weaken the basic properties

A14. The same number of electrons on the external energy level have atoms of elements with serial numbers:
1) 29 and 35 2) 9 and 25 3) 16 and 24 4) 16 and 34

A15. The elements of the third period of the Periodic system with increasing serial number have:

decrease in the number of electrons in the outer level

weakening of restorative properties

enhancement of metallic properties

increase in the radii of atoms