Chemistry presentation "Halogens. Halogen compounds"

This lesson is a lesson in the assimilation of new knowledge, is based on the presentation, all stages of the lesson are sustained from checking homework to reflection (consolidating new material). Also contains a video fragment of the experiment "combustion of antimony in chlorine".

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general characteristics halogens open lesson in chemistry in grade 9 Prepared by: Vyskrebentseva S.V. chemistry teacher MBOU secondary school No. 6 st. October

Lesson Objectives: To give an idea of ​​halogens based on their comparative characteristics; Consider simple substances - halogens, their physical and chemical properties; Continue the formation of the ability to compare the properties of simple substances.

Checking homework: testing write out the numbers of properties and characteristics for (1 option) metals, for (2 options) non-metals: Small radius of atoms Large radius of atoms At the outer level from 1 to 3 electrons At the outer level from 4 to 8 electrons Malleability Metallic luster Gaseous state of aggregation Plasticity Various colors Poor electrical conductivity Solid state of aggregation Good thermal conductivity Good electrical conductivity Pronounced reducing properties Pronounced oxidizing properties Allotropy

Correct answers: Metals are characterized by: Small radius of atoms Large radius of atoms At the external level from 1 to 3 electrons At the external level from 4 to 8 electrons Malleability Metallic luster Gaseous state of aggregation Plasticity Various colors Poor electrical conductivity Solid state of aggregation Good thermal conductivity Good electrical conductivity Pronounced reduction properties Pronounced oxidizing properties Allotropy

Correct answers: non-metals are characterized by: Small atomic radius Large atomic radius At the outer level from 1 to 3 electrons At the outer level from 4 to 8 electrons Malleability Metallic luster Gaseous state of aggregation Plasticity Various colors Poor electrical conductivity Solid state of aggregation Good thermal conductivity Good electrical conductivity Pronounced reduction properties Pronounced oxidizing properties Allotropy

Chain of transformations: H 2 → NaH → H 2 → HCl NaOH H 2 + 2Na \u003d 2NaH NaH + HCl \u003d NaCl + H 2 H 2 + Cl 2 \u003d 2HCl NaH + H 2 O \u003d NaOH + H 2 2NaOH + 2Al + 6H 2 O \u003d 2Na + 3H 2

Task No. 2 p. 93 Given: Solution: V (air) \u003d 100 l V (O 2) \u003d V (air) * ᵠ (O 2) \u003d 100 * 0.21 \u003d ᵠ (O 2) \u003d 21% 21 l. ᵠ (N 2) \u003d 78% n (O 2) \u003d V / V m \u003d 21 l / 22.4 l / mol \u003d 0.94 mol n (O 2) \u003d? V (N 2) \u003d 100 * 0.78 \u003d 78 l n (N 2) \u003d? n (N 2) \u003d 78l / 22.4l / mol \u003d 3.48mol Answer: 0.94 mol, 3.48 mol.

Problem №3 p.103 Given: Solution: m tech. (WO 3) \u003d 928 kg W (WO 3) \u003d 100% -25% \u003d 75% W (impurity) \u003d 25% m (WO 3) \u003d m those. * W (WO 3) \u003d V (H 2) \u003d? 928kg * 0.75 = 696kg n(W)=? n(WO 3) \u003d m / M \u003d 696 kg / 232 kg / kmol \u003d \u003d 3 kmol WO 3 + 3H 2 \u003d W + 3H 2 O 1 mol 3mol 1mol 3 kmol 9 kmol 3 kmol V (H 2) \u003d nV m \u003d 9 kmol * 22.4 m3 / kmol \u003d 201.6 m3 Answer: 201.6 m3, 3 kmol.

The study of new material: Position in the PSCE and the structure of atoms: VII group main subgroup

General characteristic of halogens: at the external level 7 electrons; the radius of atoms increases; o weaken non-metallic properties; o oxidative capacity is reduced. Fluorine is the strongest oxidizing agent (s.o.-1) For the rest: s.o. -1, +1, +3, +5, +7

Halogens are simple substances Fluorine F 2 is a poisonous light yellow gas with a sharp irritating odor.

Simple substances - halogens 2. Chlorine Cl 2 - a yellow-green gas with a pungent suffocating odor

Simple substances - halogens 3. Bromine Br 2 - brown liquid with a fetid odor

Simple substances - halogens 4. Iodine I 2 - a black-gray solid with a metallic luster and a pungent odor

Chemical properties of halogens Interaction with simple substances: a) with hydrogen H 2 H 2 + G 2 \u003d 2NH b) with metals F 2 reacts even with Au, Ag and Pt when heated

Combustion of antimony in chlorine

Chemical properties of halogens 2. Interaction with complex substances: a) with water 2F 2 + 2H 2 O \u003d 4HF + O 2 b) with metal halides Cl 2 → Br 2 → I 2, the oxidizing ability decreases

Homework: Paragraph 18, tasks after paragraph 18 No. 4.5 Paragraph 20, tasks after paragraph 20 No. 1 Thank you for your attention!

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SCENARIO OF AN OPEN LESSON

in chemistry in the 9th grade on the topic:

"GENERAL CHARACTERISTICS OF HALOGENS"

The purpose of the lesson: Give a general description of halogens and consider their physical and

Chemical properties.

Lesson objectives: 1) Continue the formation of skills to compare the properties of simple

Substances;

2) Fasten general ideas about non-metals and their properties;

3) Develop skills and abilities in solving problems and compiling equations

Chemical reactions involving non-metals.

Lesson type: a lesson in learning new knowledge

Lesson methods: conversation, story, independent work

Equipment: Periodic system of chemical elements D.I. Mendeleev,

Multimedia system, computer.

DURING THE CLASSES:

1. Organizing time.(1-2 min)

Greeting each other, getting ready for work, communicating the topic and goals of today's lesson.

1. Checking homework.(10-12 min)

1. Call 3 people to the board: 1 solves the chain in the middle of the board, 2 people behind the boards solve problems:

Chain of transformations:

H2 → NaH → H2 → HCl

NaOH

1. H2 + 2Na = 2NaH
2. NaH + HCl = NaCl + H2
3. H2 + Cl2 = 2HCl
4. NaH + H2O = NaOH + H2
5. 2NaOH + 2Al + 6H2O = 2Na + 3H2

Task number 2 p.93

Given: Solution:

V(air)=100 l V(O2)= V(air)* ᵠ (O2)= 100*0.21=

ᵠ (O2)=21% 21 l.

ᵠ (N2) \u003d 78% n (O2) \u003d V / Vm \u003d 21l / 22.4 l / mol \u003d 0.94 mol

N(O2)=? V (N2) \u003d 100 * 0.78 \u003d 78 l

N(N2)=? n (N2) \u003d 78l / 22.4l / mol \u003d 3.48mol

Answer: 0.94 mol, 3.48 mol.

Task number 3 p.103

Given: Solution:

Mtech.(WO3) =928 kg W(WO3) = 100%-25%=75%

W(impurity) = 25% m (WO3) = mtech. *W(WO3)=

V(H2)=? 928kg * 0.75 = 696kg

n(W)=? n(WO3)=m/M=696kg/232kg/kmol = 3 kmol

WO3 + 3H2 = W + 3H2O

1 mol 3mol 1mol

3 kmol 9 kmol 3 kmol

V (H2) \u003d nVm \u003d 9 kmol * 22.4 m3 / kmol \u003d 201.6 m3

Answer: 201.6 m3, 3 kmol.

1. All the rest write a test: select the numbers of properties and characteristics for (1st option) metals, for (2nd option) non-metals:

1. Small atomic radius
2. Large atomic radius
3. At the outer level from 1 to 3 electrons
4. At the outer level from 4 to 8 electrons
5. Ductility
6. metallic luster
7. Gaseous state of aggregation
8. Plastic
9. Various coloring
10. Poor electrical conductivity
11. Solid aggregate state
12. Good thermal conductivity
13. Good electrical conductivity
14. Pronounced restorative properties
15. Pronounced oxidizing properties
16. Allotropy

Correct answers: 1 option - 2,3,5,6,8,11,12,13,14

Option 2 - 1,4,7,9,10,11,15,16

1. Learning new material.(20 minutes)

1. Position in PSCE and the structure of their atoms.

Halogens F, Cl, Br, I, At - elements of the 7th group of the main subgroup of the Periodic Table of Chem. elements.

Fluorine is the strongest oxidizing agent (s.o.-1)

For the rest: s.o. -1, +1, +3, +5, +7

In addition to fluorine, chlorine, bromine and iodine in this group there is another element related to halogens - this is astatine. It was predicted by D.I. Mendeleev as eka-iodine, it is a radioactive element, therefore it is not studied in the school course.

1. Halogens - simple substances and their presence in nature.

Listening to messages about fluorine, chlorine, bromine and iodine. (4 people, focusing on the presentation slides, talk about halogens, the history of their discovery, about the compounds in which they occur in nature) The rest of the class is briefly outlined by the speakers.

1. Chemical properties of halogens.

1. Interaction with simple substances:

a) with hydrogen H2

H2 + G2 = 2NG

Fluorine interacts with hydrogen in any conditions with an explosion, chlorine - with an explosion only when ignited or exposed to direct sunlight, bromine reacts with hydrogen only when heated and without an explosion. These reactions are exothermic, while the reaction of iodine with hydrogen is weakly endothermic, it proceeds slowly even when heated.

b) with metals - salts are formed - metal halides.

So fluorine already under normal conditions it reacts with most metals, and when heated it even reacts with Au, Ag and Pt, known for their chemical passivity.

The remaining halogens react with metals mainly when heated. So, in a flask filled with chlorine, crystals of crushed antimony flare up and burn beautifully:

2Sb + 3Cl 2 = 2SbCl 3 (viewing a video fragment of the experiment of antimony with chlorine)

2Sb + 5Cl 2 = 2SbCl 5

An independent task is to write the equations for the reactions of iron with chlorine, copper with bromine.

2. Interaction with complex substances:

a) with water

2F2 + 2H2O = 4HF + O2

b) with metal halides(excl. is fluorine, which primarily interacts with water)

Cl2 → Br2 → I2

oxidizing power decreases from chlorine to iodine:

Cl2 + 2NaBr = 2NaCl + Br2

Br2 + 2KI = 2KBr + I2

1. Consolidation. (5 minutes.)

Answer 5 test questions on the topic studied (see presentation slides)

1. Analysis of grades for the lesson.(1 minute.)

Evaluate the d/z who answered at the blackboard and spoke about halogens.

1. Homework:(1 minute.)

Paragraph 18, tasks after it No. 4.5

Paragraph 20, task after it No. 1

Express class survey: 1. What elements are called halogens? 2. Describe the position of halogens in the Periodic system of D.I. Mendeleev. 3. What is the structure of halogen atoms? 4. Which of the halogens is the most electronegative? 5. How do the oxidizing properties of halogens change with increasing serial number?

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CFC 1970 Aerosol dispensers Refrigerants Ozone depletion Blindness due to cataracts Skin cancers Suppression of the body's immune system CI + O 3 = CIO ​​+ O 2 One chlorine atom destroys O 3 molecules and can last up to 300 years.

Questions Answer options 1) What is common in the structure of halogen atoms: a) the radius of the atom b) the charge of the nucleus c) the number of electrons in the outer layer 2) How does the electronegativity in the group: F-Cl-Br-I: a) decreases b) increases c) does not change 3) Which of the substances taken in pairs can be used to obtain hydrogen chloride: a) NaCl (TV) and H 2 SO 4 (solution) b) NaCl (solution) and H 2 SO 4 (solution) in ) NaCl (TV) and H 2 SO 4 (k) 4) It is possible to distinguish halogen acids and their salts (except for fluorine compounds) using one reagent: a) KCl b) AgNO 3 c) BaSO 4 5) Name the liquid halogen: a ) chlorine b) bromine c) iodine Test

“Iodine in the human body” - If the first line disappeared in the morning, everything is fine with iodine. Beautiful dark blue crystals of iodine are most similar to graphite. The daily requirement of an adult for iodine is 0.1-0.2 mg. Reacts with concentrated sulfuric and nitric acids, metals, non-metals, alkalis, hydrogen sulfide.

"Iodine in the body" - It is better to buy vegetables from the seaside. Objectives: Lack of iodine in the body can lead to: Examine food for the qualitative and quantitative content of iodine. Х2 = (v-v1) 0.0001058 kn 100 m. Do not take bulk iodized salt.

"Oxygen cycle in nature" - Prevalence: Earth's crust - 47.4% (by mass); Hydrosphere - 88.8% (by mass); Atmosphere - 20.95% (by volume). General information about the element. Migration, and, consequently, cycles, are determined by: The oxygen cycle. Photosynthesis. The most important provisions of geochemistry: Electronic configuration - 2s22p4.

"Hydrogen bond" - occurs 2) inside the DNA molecule (between nitrogenous bases according to the principle of complementarity: A - T, C - G). H?+ - f?? . . . h?+ – F?-. High temperatures. Factors that destroy the hydrogen bond in a protein molecule (denaturing factors). 2) between ammonia molecules. 4) between molecules of carboxylic acids (formic, acetic) (dimers of carboxylic acids).

"Iron compounds" - Therefore, iron belongs to d - elements and exhibits variable valency (II) and (III). 6. Electronic formula of the structure of the atom: 1s 2s 2p 3s 3p 3d 4s. Relative atomic mass - 56. The structure of the atom: +26)2)8)14)2. The content of iron in the earth's crust is 5% (mass). In the composition of mineral waters in nature, iron is included in the form of sulfate and bicarbonate.