The habitat of flat worms. Flat Worms: Facilities of the structure, species and general characteristics

Theme lesson: Mass fraction chemical element in connection.

THE PURPOSE OF THE LESSON: Teach to calculate the mass fraction of the elements in the compound by the compound formula and establish the chemical formula of a complex substance according to the well-known mass fractions of chemical elements.

Basic concepts. Mass fraction of the chemical element.

Planned learning results

Subject. To be able to calculate the mass proportion of the element in the compound according to its formula and establish the chemical formula of a complex substance according to the well-known mass fractions of chemical elements.

MetaPermet . To form skills to establish analogies, use algorithms for solving educational and informative tasks.

The main activities of students. Calculate the mass fraction of the element in the compound according to its formula. Install the chemical formula of a complex substance according to the well-known mass fractions of chemical elements.

Structure lesson

I.. Organizational stage

II.. Actualization supporting knowledge

III. Studying a new material

IV. Fastening. Summing up the lesson

V.. Homework

During the classes

Organizing time.

Check your homework.

Actualization of reference knowledge.

Give definitions: relative atomic mass, relative molecular weight.

In which units can be measured by the relative atomic mass.

In which units can be measured by the relative molecular weight.

Studying a new material.

Working with a textbook. Workbook.

Guys, let's say we have a substance - sulfuric acidH. 2 SO. 4,

we can find out which atoms are part of the connection.

And their number?

And in what mass ratio they connect?

Calculation of bulk chemical relations

elements in complex substance. (p. 51)

And how can I find out in what mass relationships the elements are connected in the compound of the formulaH. 2 SO. 4 ?

m.(H.): m.(S.): m.(O.)= 2*2 + 32 + 16*4= 2:32:64 = 1:16:32.

1 + 16 + 32 \u003d 49, that is, 49 mass parts of sulfuric acid, contain 1 mass portion of hydrogen, 16 mass parts of sulfur, 32 mass parts of oxygen.

Guys, how do you think, can we calculate the share of each element in the connection?

Today we will get acquainted with a new concept. mass fraction Element in connection.

W. - Mass fraction of the element in the compound.

n. - The number of element atoms.

Mr. - relative molecular mass.

Calculation of mass fractions of chemical elements

in a complex substance. (RT)

1. Examine the algorithm for calculating the mass fraction of the element in the compound.

Task number 1 (RT)

Withdrawal of chemical formulas, if mass fractions of chemical elements are known,

included in this substance. (RT)

2. Examine the algorithm for calculating the mass fraction of the element in the connection.

Task number 5 (RT)

Fastening the material studied.

RT p. 25 №2.

RT p. 27 №6.

Summing up the lesson.

What new concepts did you find out today at the lesson?

Independent work.

Homework:

• explore §15 p. 51 - 53;

  answer questions №3,4,7 p. 53-54 (writing).

P literature tank.

Textbook. Chemistry grade 8. Auto G.E. Rudzitis, F.G. Feldman. Publishing House "Enlightenment", 2014.

Workbook in chemistry. Auto Borovski TA

At the moment, about 120 different chemical elements are known, of which in nature can be found no more than 90. The diversity of various chemicals around us is incommensurable more than this number.
This is due to the fact that extremely rare chemicals consist of separate, non-interchangeable atoms of chemical elements. In such a building, only a small number of gases called noble - helium, Neon, Argon, Krypton, Xenon and Radon has such a structure. More often, chemicals are not consisting of disparate atoms, but from their associations in various groups.
That is, atoms of most chemical elements are able to communicate with each other. Most often, as a result, molecules are obtained - particles representing groups of two or more atoms. For example, the hydrogen chemical consists of hydrogen molecules, which are formed from atoms as follows:

Figure 3. Formation of hydrogen molecule

Atoms of different chemical elements can both form connections with each other, for example, the interaction of an oxygen atom with two hydrogen atoms is formed by a water molecule:

Figure 4. Education of water molecule

Since each time the atoms of chemical elements and are inconvenient to sign them, to reflect the composition of the molecules were invented chemical formulas. For example, the molecular hydrogen formula is written as H 2, where the number 2 written by the substrate on the right of the symbol of the hydrogen atom means the number of atoms of this type in the molecule. Thus, the water formula can be written as H 2 O. The unit that should show the number of oxygen atoms in the molecule, according to the rules adopted in chemistry, are not written. The numbers denoting the amounts of atoms in the composition of one molecule are called indexes.
Consider some more examples of chemical formulas. Thus, ammonia formula is written as NH 3, which indicates that each ammonia molecule consists of one nitrogen atom and three hydrogen atoms.
We often encounter molecules in which you can count several identical groups of atoms. For example, from Al 2 aluminum sulfate formula (SO 4) 3, it can be concluded that the composition of the molecules of this substance are two groups of SO 4 atoms.
Thus, the chemical formulas of substances are uniquely characterized by both their high-quality and quantitative composition.
Of all the above, the law of constancy of the composition of the substance established in 1808 by the French scientist Joseph Louis Proustom, and he sounds as follows:

Any pure chemical has a permanent qualitative and quantitative composition, independent of the method of obtaining this substance.

Since any chemical substance is a combination of the molecules of the same composition, this leads to the fact that the proportions between the atoms of the chemical elements in any portion of the substance are the same as in the same molecule of this substance. All differences in B. chemical properties Substances depend on the quantitative and qualitative composition of molecules and besides, on the order of bonds of atoms among themselves, if so is possible.
Thus, it is possible to give the following definition of the term molecule:

Molecule is the smallest particle of any chemical substance His chemical properties.

Similar to relative atomic mass, there is also such a concept as a relative molecular weight M R.:

The relative molecular weight (M r) of the substance is the ratio of the mass of one molecule of this substance to one twelfth mass of one carbon atom (1 atomic unit of mass).

Thus, it is obvious that the relative molecular weight consists of relative atomic masses Elements, each of which is multiplied by the number of atoms of this particular type in one molecule. For example, the relative molecular weight of the HNO 3 nitric acid molecule is folded from the relative atomic mass of hydrogen, the relative atomic mass of nitrogen and the three relative atomic masses of oxygen:

To describe the qualitative and quantitative composition of the substance use such a concept as a mass fraction of the chemical element w (X).

2. What way of life is representatives of various groups of flat worms? How are the features of the structure of worms with a way life. And habitat?

2) What lifestyle is representatives of various groups of flat worms? How are the features of the structure of worms with the lifestyle and the habitat?

representatives of various classes? How are the features of the structure of worms with the lifestyle and their habitat lifestyle? 3. An example of the features of the structure of flat, round and ring worms List signs of complication of the organization compared to intestinal. 4. What diseases cause flat worms? What is their prevention? 5. What features of the structure and lifestyle are characteristic of representatives of the type Round worms? 6. Why did the collee worms got such a name? What is characteristic of the structure of each segment? 7. On the basis of what signs of ringed worms belong to more complex animals than previously studied

12 body cavity in ascaris a) is filled with connective tissue b) filled with liquid B) filled with air d) missing
13 In every segment of the body of the rainwater worm are repeated a) Nervous nodes b) excretory tubes c) Ring blood vessels d) are true all answers
14 In the rainworm from the senses, there are a) Salfing b) taste c) hearing d) there is no special senses
15 The rainworm breathes a) in an oxygen-free medium b) atmospheric air c) both options d) absence is absent
16 Sinks of an ordinary string coated with a layer a) lime b) rod-like substance c) chitin d) silicon
17 In the circulatory system of the string
a) two-chamber heart and one circle circulation b) two-chamber heart and an unlocked blood system C) open circulatory system, the heart function is performed by two vessels in front of the body d) one-chamber heart and an unlocked blood system
18 To the bucculent mollusks include a) naked slug b) grunce c) beribon d) true all answers
19 chitinist cover arthropods performs functions a) protection b) thermoregulation c) gas exchange d) true all answers
20 Heart of cancer has a) two departments: atria and ventricle b) three departments: two atrium and one ventricle c) one department d) absent heart
21 Nervous system Cancer consists of a) a) nerve node b) of a sodlilt nerve node c) the abdominal nervous chain g) are true all the answers
22 Brystko Pauka-Crossing has a) Three segments b) five segments c) the non-grinstone structure d) None of the answers is faithful
23 The process of digestion at Spider-Cross:
a) domestic b) partially extra-complete c) completely unsolveged d) liquid components digested outside the digestive system, and solid spider stomach
24 The body of arthropods consists of:
a) heads, chest and abdomen b) heads and torsions c) pumped and trunking d) heads, chest and abdomen; Chawns and abdomen.
25 Insects, the number of paths of motor limbs may be equal
a) 3 b) 4 c) 5 g) are true all answers
26 oxygen to insect tissues comes from diffusion through
a) the walls of the capillaries b) the walls of the trachea c) the walls of the pulmonary bags d) arrives first in the trachea, then in the capillaries
27 Fish belong to type:
a) Beshorda b) semi-ferrous c) chord
28 The body is covered with bone scales: a) only in cartilage fish b) only in bone fish c) in all fish, with rare exceptions
29 fish eyes are always open, because they have:
a) eyelids have grown and turned into a transparent shell b) there are no eyelids in) eyelids stationary
30 spinal cord among fish is
a) under the spine b) in the spine, which forms the upper arc vertebrals c) above the spine
31 Blood System
a) closed b) open-in) open in cartilage and closed in bone
32 Fish Temperature
a) constant, and does not depend on the temperature of the medium b) is a non-permanent, but it does not depend on the temperature of the medium) a non-permanent and depends on the temperature of the medium
33 leather in reptiles
a) has sebaceous glands b) dry (without glands) c) has a small amount of glazing glands
34 Heart in reptiles
a) three-chamber b) three-chamber, except for crocodtlov c) four-chamber
35 Fertilization in reptiles
a) external b) internal c) both outdoor and internal
36 dirbs is
a) a naked lizard b) snakes c) a special group of reptiles
37 In all mammals, the chest cavity is separated from the abdominal rughead
a) brigade b) ganglia c) diaphragm d) cuticle
38 The following element belongs to the skeleton of the lower limb
a) Tsevka b) thigh c) shin d) radiation bone
39 animals characterized by radiation body symmetry
a) mollusks b) flat worms c) shepherd g) fish
40 Exclude too much
a) shovel b) clavicle c) Voronene dice d) shoulder bone
41 bird science is
a) poultry farming b) ornithology c) cynology d) zoology
42 Kiel on Bird Breasts
a) contributes to the dissection of air during flight b) increases the area of \u200b\u200battachment of the breast muscles B) does not matter how tool to fly
43 What digestive organs arose in birds due to their lack of jaws and teeth
a) goiter b) iron stomach b) muscular gastric d) slim intestine
44 mammals spread on earth due to the fact that
a) had minor sizes b) fed the young milk c) were warm-blooded d) are true all answers
45 fabrics for the first time appeared
a) the simplest b) intestinal c) flat worms d) ringed worms
46 Darwin Theory argues that all organisms
a) unchanged and created by the highest forces b) were first created, and then evolved natural way c) arose and