See also: List chemical elements by atomic number and Alphabetical list chemical elements Contents 1 Symbols used in this moment... Wikipedia

    See also: List of chemical elements by symbol and Alphabetical list of chemical elements This is a list of chemical elements arranged in ascending order of atomic number. The table shows the name of the element, symbol, group and period in ... ... Wikipedia

    - (ISO 4217) Codes for the representation of currencies and funds (eng.) Codes pour la représentation des monnaies et types de fonds (fr.) ... Wikipedia

    The simplest form of matter that can be identified chemical methods. These are the components of simple and complex substances, which are a collection of atoms with the same nuclear charge. The charge of the nucleus of an atom is determined by the number of protons in... Collier Encyclopedia

    Contents 1 Paleolithic Age 2 10th millennium BC e. 3 9th millennium BC er ... Wikipedia

    Contents 1 Paleolithic Age 2 10th millennium BC e. 3 9th millennium BC er ... Wikipedia

    This term has other meanings, see Russians (meanings). Russian ... Wikipedia

    Terminology 1: : dw Number of the day of the week. "1" corresponds to Monday Term definitions from various documents: dw DUT Difference between Moscow and UTC, expressed as an integer number of hours Term definitions from ... ... Dictionary-reference book of terms of normative and technical documentation

"Chemical element - sulfur" - Natural intergrowth of crystals of native sulfur. Molecules with closed (S4, S6) chains and open chains are possible. Sulfur ores are mined in different ways - depending on the conditions of occurrence. Natural sulfur minerals. We must not forget about the possibility of its spontaneous combustion. Open pit mining. Walking excavators remove layers of rocks under which ore lies.

"Questions on chemical elements" - Can be stable and radioactive, natural and artificial. Associated with a change in the number of energy levels in the main subgroups. 8. What element does not have a permanent "registration" in the Periodic system? They are in constant motion. Tellurium, 2) selenium, 3) osmium, 4) germanium. Where does arsenic accumulate?

"H2O and H2S" - Sulfate ion. Y=? K K2 \u003d 1.23 10? 13 mol / l. Preparation: Na2SO3 + S = Na2SO3S (+t, aq. solution). AT aqueous solution: +Hcl (ether). Vitriols MSO4 5(7)H2O (M – Cu, Fe, Ni, Mg …). Sulfuric acid H2SO4. Structure of SO32– and HSO3– anions. = y. The SO3 molecule is non-polar and diamagnetic. ? . Hydrosulfite ion: tautomerism.

"Periodic Table of Chemical Elements" - 8. How many electrons can be in the third energy level? Arrange elements in ascending order metallic properties. Name of the country: "Chemical elementary". Poems by Stepan Shchipachev. A. 17 B. 35 C. 35.5 D. 52 6. How many electrons revolve around the nucleus in a fluorine atom?

"Calcium Ca" - Ca compounds. Chemical properties of Ca. Physical properties of Ca. Calcium is one of the common elements. Application. Obtaining calcium in industry. Calcium Ca. Describe physical properties Ca. Finding in nature. Task to repeat. Calcium Ca is a silvery white and rather hard metal, light.

"The element phosphorus" - Phosphorus is the 12th most abundant element in nature. Interaction with simple substances - non-metals. interaction with metals. To bind calcium compounds, quartz sand is added. When white phosphorus is heated in an alkali solution, it disproportionates. Phosphorus. Black phosphorus.

There are 46 presentations in total in the topic

How to use the periodic table? For an uninitiated person, reading the periodic table is the same as looking at the ancient runes of elves for a dwarf. And the periodic table can tell a lot about the world.

In addition to serving you in the exam, it is also simply indispensable for solving a huge number of chemical and physical tasks. But how to read it? Fortunately, today everyone can learn this art. In this article we will tell you how to understand the periodic table.

The periodic system of chemical elements (Mendeleev's table) is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of the atomic nucleus.

History of the creation of the Table

Dmitri Ivanovich Mendeleev was not a simple chemist, if someone thinks so. He was a chemist, physicist, geologist, metrologist, ecologist, economist, oilman, aeronaut, instrument maker and teacher. During his life, the scientist managed to conduct a lot of fundamental research in various fields of knowledge. For example, it is widely believed that it was Mendeleev who calculated the ideal strength of vodka - 40 degrees.

We do not know how Mendeleev treated vodka, but it is known for sure that his dissertation on the topic “Discourse on the combination of alcohol with water” had nothing to do with vodka and considered alcohol concentrations from 70 degrees. With all the merits of the scientist, the discovery periodic law chemical elements - one of the fundamental laws of nature, brought him the widest fame.


There is a legend according to which periodic system dreamed of a scientist, after which he only had to finalize the idea that had appeared. But, if everything were so simple .. This version of the creation of the periodic table, apparently, is nothing more than a legend. When asked how the table was opened, Dmitry Ivanovich himself answered: “ I’ve been thinking about it for maybe twenty years, and you think: I sat and suddenly ... it’s ready. ”

In the middle of the nineteenth century, attempts to streamline the known chemical elements (63 elements were known) were simultaneously undertaken by several scientists. For example, in 1862 Alexandre Émile Chancourtois placed the elements along a helix and noted the cyclical repetition of chemical properties.

Chemist and musician John Alexander Newlands proposed his version of the periodic table in 1866. An interesting fact is that in the arrangement of the elements the scientist tried to discover some mystical musical harmony. Among other attempts was the attempt of Mendeleev, which was crowned with success.


In 1869, the first scheme of the table was published, and the day of March 1, 1869 is considered the day of the discovery of the periodic law. The essence of Mendeleev's discovery was that the properties of elements with increasing atomic mass do not change monotonously, but periodically.

The first version of the table contained only 63 elements, but Mendeleev made a number of very non-standard decisions. So, he guessed to leave a place in the table for yet undiscovered elements, and also changed the atomic masses of some elements. The fundamental correctness of the law derived by Mendeleev was confirmed very soon after the discovery of gallium, scandium and germanium, the existence of which was predicted by scientists.

Modern view of the periodic table

Below is the table itself.

Today, instead of atomic weight (atomic mass), the concept of atomic number (the number of protons in the nucleus) is used to order elements. The table contains 120 elements, which are arranged from left to right in ascending order of atomic number (number of protons)

The columns of the table are so-called groups, and the rows are periods. There are 18 groups and 8 periods in the table.

  1. The metallic properties of elements decrease when moving along the period from left to right, and in reverse direction- increase.
  2. The dimensions of atoms decrease as they move from left to right along the periods.
  3. When moving from top to bottom in the group, the reducing metallic properties increase.
  4. Oxidizing and non-metallic properties increase along the period from left to right.

What do we learn about the element from the table? For example, let's take the third element in the table - lithium, and consider it in detail.

First of all, we see the symbol of the element itself and its name under it. In the upper left corner is the atomic number of the element, in the order in which the element is located in the table. The atomic number, as already mentioned, is equal to the number of protons in the nucleus. The number of positive protons is usually equal to the number of negative electrons in an atom (with the exception of isotopes).

The atomic mass is indicated under the atomic number (in this version of the table). If we round the atomic mass to the nearest integer, we get the so-called mass number. The difference between the mass number and the atomic number gives the number of neutrons in the nucleus. Thus, the number of neutrons in a helium nucleus is two, and in lithium - four.

So our course "Mendeleev's Table for Dummies" has ended. In conclusion, we invite you to watch a thematic video, and we hope that the question of how to use the periodic table of Mendeleev has become more clear to you. We remind you that learning a new subject is always more effective not alone, but with the help of an experienced mentor. That is why, you should never forget about the student service, which will gladly share their knowledge and experience with you.

If the periodic table seems difficult for you to understand, you are not alone! Although it can be difficult to understand its principles, knowing how to work with it will help in learning natural sciences. To get started, study the structure of the table and what information can be learned from it about each chemical element. Then you can start exploring the properties of each element. And finally, using the periodic table, you can determine the number of neutrons in an atom of a particular chemical element.

Steps

Part 1

Table structure

    The periodic table, or periodic table of chemical elements, begins at the top left and ends at the end of the last line of the table (bottom right). The elements in the table are arranged from left to right in ascending order of their atomic number. The atomic number tells you how many protons are in one atom. In addition, as the atomic number increases, so does the atomic mass. Thus, by the location of an element in the periodic table, you can determine its atomic mass.

  1. As you can see, each next element contains one more proton than the element preceding it. This is obvious when you look at the atomic numbers. Atomic numbers increase by one as you move from left to right. Since the elements are arranged in groups, some table cells remain empty.

    • For example, the first row of the table contains hydrogen, which has atomic number 1, and helium, which has atomic number 2. However, they are on opposite ends because they belong to different groups.

  2. Learn about groups that include elements with similar physical and chemical properties. The elements of each group are located in the corresponding vertical column. As a rule, they are indicated by the same color, which helps to identify elements with similar physical and chemical properties and predict their behavior. All elements of a particular group have the same number of electrons in the outer shell.

    • Hydrogen can be attributed both to the group of alkali metals and to the group of halogens. In some tables it is indicated in both groups.
    • In most cases, the groups are numbered from 1 to 18, and the numbers are placed at the top or bottom of the table. Numbers can be given in Roman (eg IA) or Arabic (eg 1A or 1) numerals.
    • When moving along the column from top to bottom, they say that you are "browsing the group".

  3. Find out why there are empty cells in the table. Elements are ordered not only according to their atomic number, but also according to groups (elements of the same group have similar physical and chemical properties). This makes it easier to understand how an element behaves. However, as the atomic number increases, elements that fall into the corresponding group are not always found, so there are empty cells in the table.

    • For example, the first 3 rows have empty cells, since transition metals are found only from atomic number 21.
    • Elements with atomic numbers from 57 to 102 belong to the rare earth elements, and they are usually placed in a separate subgroup in the lower right corner of the table.

  4. Each row of the table represents a period. All elements of the same period have the same number of atomic orbitals in which electrons are located in atoms. The number of orbitals corresponds to the period number. The table contains 7 rows, that is, 7 periods.

    • For example, the atoms of the elements of the first period have one orbital, and the atoms of the elements of the seventh period have 7 orbitals.
    • As a rule, periods are indicated by numbers from 1 to 7 on the left of the table.
    • As you move along a line from left to right, you are said to be "scanning through a period".

  5. Learn to distinguish between metals, metalloids and non-metals. You will better understand the properties of an element if you can determine what type it belongs to. For convenience, in most tables, metals, metalloids and non-metals are indicated by different colors. Metals are on the left, and non-metals are on the right side of the table. Metalloids are located between them.

    Part 2

    Element designations

    1. Each element is designated by one or two Latin letters. As a rule, the element symbol is shown in large letters in the center of the corresponding cell. A symbol is an abbreviated name for an element that is the same in most languages. When experimenting and working with chemical equations element symbols are commonly used, so it's good to remember them.

      • Typically, element symbols are shorthand for their Latin name, although for some, especially recently discovered elements, they are derived from the common name. For example, helium is denoted by the symbol He, which is close to the common name in most languages. At the same time, iron is designated as Fe, which is an abbreviation of its Latin name.

    2. Pay attention to the full name of the element, if it is given in the table. This "name" of the element is used in normal texts. For example, "helium" and "carbon" are the names of the elements. Usually, although not always, full names elements are listed below their chemical symbol.

      • Sometimes the names of the elements are not indicated in the table and only their chemical symbols are given.

    3. Find the atomic number. Usually the atomic number of an element is located at the top of the corresponding cell, in the middle or in the corner. It can also appear below the symbol or element name. Elements have atomic numbers from 1 to 118.

      • The atomic number is always an integer.

    4. Remember that the atomic number corresponds to the number of protons in an atom. All atoms of an element contain the same number of protons. Unlike electrons, the number of protons in the atoms of an element remains constant. Otherwise, another chemical element would have turned out!

      • The atomic number of an element can also be used to determine the number of electrons and neutrons in an atom.

    5. Usually the number of electrons is equal to the number of protons. The exception is the case when the atom is ionized. Protons have a positive charge and electrons have a negative charge. Since atoms are usually neutral, they contain the same number of electrons and protons. However, an atom can gain or lose electrons, in which case it becomes ionized.

      • Ions have electric charge. If there are more protons in the ion, then it has a positive charge, in which case a plus sign is placed after the element symbol. If an ion contains more electrons, it has a negative charge, which is indicated by a minus sign.
      • The plus and minus signs are omitted if the atom is not an ion.

The ancient Greek sages were the first to say the word "element", and this happened five centuries before our era. True, the "elements" of the ancient Greeks were considered earth, water, air and fire, and not at all iron, oxygen, hydrogen, nitrogen and other elements of today's chemists.

In the Middle Ages, scholars already knew ten chemical elements- seven metals(gold, silver, copper, iron, tin, lead and mercury) and three non-metal(sulphur, carbon and antimony).

See what "mercury" is in other dictionaries

Most solid material in the human body - tooth enamel. It must be hard, so that our teeth can serve us for a lifetime of biting and chewing; however, be that as it may, tooth enamel is susceptible to chemical attack. Acids found in certain foods or made by bacteria that feed on food debris on our teeth can dissolve enamel. Unprotected by enamel, the tooth will begin to decay, thereby developing cavities and other dental problems.

After several years of research, it has been found that excess fluoride compounds in drinking water are responsible for both of these effects. The protective effects of fluorine have a simple chemical explanation. Tooth enamel is made up primarily of a mineral called hydroxyapatite, which is composed of calcium, phosphorus, oxygen, and hydrogen. We now know that fluorine combines with hydroxyapatite to produce fluorapatite, which is more resistant to acid breakdown than hydroxyapatite. This deliberate fluoridation, combined with the use of fluoride-containing toothpastes and improved oral hygiene, resulted in a 60% reduction in tooth decay in children.

The alchemists took a very long time without chemical formulas. There were strange signs in use, and almost every chemist used his own system of notation for substances. And the descriptions of chemical transformations were like fairy tales and legends.
Here is how, for example, the alchemists described the reaction of mercury oxide (a red substance) with hydrochloric (hydrochloric) acid:

The nationwide reduction in caries was hailed as a major achievement public health in history. Just as language has an alphabet from which words are built, chemistry has an alphabet from which matter is described. However, the chemical alphabet is larger than the one we use to write. You may have already figured out that the chemical alphabet is made up of chemical elements. Their role is central to chemistry as they combine into millions and millions of known compounds.

The element is the basic chemical building block of matter; it is the simplest chemical. Chemical symbols are useful for short-term representation of the elements present in a substance.

  • Define a chemical element and give examples of the abundance of various elements.
  • Represent a chemical element with a chemical symbol.
  • Sodium mercury phosphorus potassium iodine.
  • Which element is represented by each chemical symbol?
  • Give some examples of how the number of elements changes.
  • Why are chemical symbols so useful?
  • What is the source of the letter for the chemical symbol?
  • Elements range from a small percentage to over 30% of the atoms around us.
  • The letters usually come from the name of the element.
  • All matter is made up of elements.
  • Chemical elements are represented by a one- or two-letter symbol.
  • Sodium water liquefied nitrogen.
Which of the following substances are elements?

"There was a red lion - and he was the groom,
And in a warm liquid they crowned him
With a beautiful lily, and warmed them with fire,
And they were transferred from vessel to vessel ... "
(J. W. Goethe, "Faust")

The alchemists believed that the chemical elements were associated with the stars and planets and assigned them astrological symbols. Gold was called the Sun, and was indicated by a circle with a dot; copper - Venus, the symbol of this metal was the "Venus mirror", and iron - Mars; as befits a god of war, the designation of this metal included a shield and a spear:

Carbon concrete paper. . Write chemical symbol for each element. Element is not an element, not an element, not an element. . By convention, the second letter in an element symbol always has lowercase values.

  • Explain how all matter is made up of atoms.
  • Describe modern atomic theory.
You now have two smaller pieces of aluminum foil. Cut one of the pieces in half. Cut one of these smaller pieces in half. Continue cutting, making smaller and smaller pieces of aluminum foil.

It should be obvious that the pieces are still aluminum foil; they just get smaller and smaller. But how far can you take this exercise, at least theoretically? Can you continue cutting aluminum foil into halves forever, making smaller and smaller pieces? Or is there some limit, some absolute smallest piece of aluminum foil?

In the 18th century, a system of designation of elements (of which three dozen had already become known at that time) took root in the form of geometric figures - circles, semicircles, triangles, squares. This way of depicting chemicals was invented by the English scientist, physicist and chemist John Dalton.

However, to distinguish chemical symbols different elements in books and scientific journals was quite difficult. And what was it like to work as typesetters in the then printing houses! How were they to distinguish the sign of hydrogen, which was three concentric circles drawn with a solid line, and with a dot in the center, from the sign of oxygen, also three concentric circles, one of which was dashed, and without a dot?
Here are the symbols for oxygen, sulfur, hydrogen and nitrogen that Dalton used:

Career Focus: Clinical Chemist

Figure 11 Trends on the periodic table.

The relative sizes of atoms show several trends in the structure of the periodic table. The atoms get larger down the column and pass less through the period. Clinical chemistry is the field of chemistry concerned with the analysis of bodily fluids to determine the state of health of the human body. Clinical chemists measure substances ranging from simple elements such as sodium and potassium to complex molecules such as proteins and enzymes in blood, urine, and other body fluids.

Finally, in 1814, symbols and names of chemical elements appeared, which chemists use to this day. The Swedish chemist Jöns-Jakob Berzelius suggested designating chemical elements by the first letter (or the first and one of the following letters) of the element's Latin name.
For example, hydrogen(in Latin "hydrogenium", Hydrogenium) - H (read "ash"), carbon(in Latin "carboneum", carboneum) - C, (in Latin "aurum", Aurum) - Au (also read "aurum").

The absence or presence or abnormally low or high amounts of a substance may be a sign of a disease or health condition. Many clinical chemists use complex technique and complex chemical reactions in their job, so they not only need to understand basic chemistry, but also be familiar with special tools and how to interpret test results.

Elements are organized by atomic number. in the left three quarter of the periodic table, the right quarter of the periodic table is the next-last column of the periodic table - the middle part of the periodic table. As you go through the periodic table, atomic radii decrease; as you go down the periodic table, atomic radii increase.

The Russian names of many elements sound completely different from the Latin ones, but what can you do - you have to memorize the chemical symbols, just as medical students, future doctors memorize Latin terms.

It is quite clear that remembering all the symbols and names of elements at once (and there are 114 of them now known) is an impossible task. Therefore, for starters, you can limit yourself to the most common:

Some characteristics of the elements are related to their position on the periodic table. What elements have chemical properties similar to those of magnesium? sodium fluorine calcium barium selenium. The chemical elements are arranged on a diagram called the periodic table. . What elements have chemical properties similar to those of lithium?

Sodium calcium beryllium barium potassium. . What elements have chemical properties similar to those of chlorine? In order for you to understand the material in this chapter, you should review the meanings of the following bold terms and ask yourself how they relate to the topics in this chapter.

Russian name Chemical symbol and atomic number of an element latin
title		 Symbol pronunciation
Nitrogen 7 N Nitrogenium en
Aluminum 13 Al Aluminum aluminum
Bromine 35 Br Bromum bromine
Hydrogen 1H Hydrogenium ash
Helium 2 He Helium helium
Iron 26 Fe Ferrum ferrum
Gold 79 Au Aurum aurum
iodine 53 I Iodum iodine
Potassium 19K Kalium potassium
Calcium 20Ca Calcium calcium
Oxygen 8 O Oxygenium about
Silicon 14Si Silicium silicium
Magnesium 12 mg Magnesium magnesium
Copper 29 Cu Cuprum cuprum
Sodium 11 Na sodium sodium
Tin 50 sn Stannum stannum
Lead 82Pb Plumbum plumbum
Sulfur 16S Sulfur es
Silver 47 Ag Argentum argentum
Carbon 6C carboneum tse
Phosphorus 15p Phosphorus pe
Fluorine 9F Fluorum fluorine
Chlorine 17Cl Chlorum chlorine
Chromium 24Cr Chromium chromium
Zinc 30 Zn Zincum zinc

Names and symbols of chemical elements



§ 4. Chemical signs and formulas

Symbolic models in chemistry include signs or symbols of chemical elements, formulas of substances and equations of chemical reactions that underlie "chemical writing". Its founder is the Swedish chemist Jens Jakob Berzelius. Berzelius' writing is based on the most important of the chemical concepts - "chemical element". A chemical element is a type of identical atoms.

An element is a substance that cannot be broken down into simpler chemical substances. Only about 90 natural elements are known. They have different abundances on Earth and in the body. Each element has a one- or two-letter chemical symbol. Modern atomic theory states that the smallest part of an element is an atom. Individual atoms are extremely small, on the order of 10 -10 m across. Most elements exist in their pure form as individual atoms, but some exist as diatomic molecules.

Atoms themselves are made up of subatomic particles. An electron is a tiny subatomic particle with a negative charge. The proton has a positive charge and, although small, is much larger than the electron. The neutron is also much larger than the electron, but has no electrical charge.

Berzelius suggested designating chemical elements by the first letter of their Latin names. So the first letter of its Latin name became the symbol of oxygen: oxygen - O (read "o", because the Latin name of this element oxygenium). Accordingly, hydrogen received the symbol H (read "ash", because the Latin name of this element hydrogenium), carbon - C (read "ce", because the Latin name of this element carboneum). However, the Latin names for chromium ( chromium), chlorine ( chlorum) and copper ( cuprum) as well as carbon, start with "C". How to be? Berzelius proposed an ingenious solution: write such symbols as the first and one of the subsequent letters, most often the second. So, chromium is designated Cr (read "chromium"), chlorine - Cl (read "chlorine"), copper - Cu (read "cuprum").

Protons, neutrons and electrons have a specific arrangement in an atom. The proton and neutrons are at the center of the atom, grouped into a nucleus. The electrons are in fuzzy clouds around the nucleus. Each element has a characteristic number of protons in its nucleus. This number of protons is the element's atomic number. An element can have a different number of neutrons in the nuclei of its atoms; such atoms are called isotopes. The two isotopes of hydrogen are deuterium, with a proton and a neutron in its nucleus, and tritium, with a proton and two neutrons in its nucleus.

Russian and Latin names, signs of 20 chemical elements and their pronunciation are given in Table. 2.

There are only 20 elements in our table. To see all 110 elements known today, you need to look at the table of chemical elements of D.I. Mendeleev.

table 2

Names and symbols of some chemical elements

Russian name

The sum of the numbers of protons and neutrons in a nucleus is called the mass number and is used to separate isotopes from each other. The masses of individual atoms are measured in units of atomic mass. Since different isotopes of an element have different masses, the atomic mass of an element is the weighted average of the mass of all naturally occurring isotopes of the element.

The modern theory of electron behavior is called quantum mechanics. According to this theory, electrons in atoms can only have specific or quantized energies. The electrons are grouped into general regions called shells, and within them, into more specific regions called subshells. There are four types of subshells, and each type can hold up to a maximum number of electrons. The distribution of electrons into shells and subshells is the electronic configuration of an atom. Chemistry usually arises from interactions between electrons in the outermost shell different atoms called valence shell electrons.

chemical sign

Pronunciation

Latin name

Aluminum

The electrons in the inner shells are called the electrons of the nucleus. Elements are grouped according to similar chemical properties in a diagram called the periodic table. The vertical columns of elements are called groups or families. Some of the element groups have names such as alkali metals, alkaline earth metals, halogens and noble gases. The horizontal row of elements is called a period. Periods and groups have a different number of elements in them. The periodic table divides the elements into metals, non-metals and semi-metals.

Aluminum

hydrargyrum

The periodic table is also divided into the main group elements, transition metals, lanthanide elements and actinide elements. The lanthanide and actinide elements are also referred to as internal elements. transition metal. The shape of the periodic table reflects the successive filling of shells and subshells in atoms.

The periodic table helps us understand trends in certain properties of atoms. One of these properties is the atomic radius of atoms. From top to bottom of the periodic table, the atoms get bigger because the electrons occupy larger and larger shells. From left to right across the periodic table, the electrons fill the same shell, but are attracted by the increasing positive charge from the nucleus, and hence the atoms become smaller.

Argentum

Most often, the composition of substances includes atoms of several chemical elements. You can depict the smallest particle of a substance, for example, a molecule, using ball models, as you did in the previous lesson. On fig. 33 depicted three-dimensional models water molecules (a), sour gas (b), methane (in) and carbon dioxide (G).

What is the mass of an electron in units of atomic mass? In a footnote in this chapter, an alpha particle was defined as a particle with 2 protons and 2 neutrons. What is the mass in grams of an alpha particle? What is the atomic mass of the mythical world? Since the distribution of isotopes is different on different planets in solar system, the average atomic mass of any element differs from planet to planet. What is the atomic mass of hydrogen on Mercury? What else are chemical elements?

And while the answer to this question was easy to enunciate, the questions are even more interesting: Can we discover or create an infinite number of chemical elements? What will they serve us for? How are their names and symbols chosen? chemical substances?

More often, chemists use symbolic models rather than material models to designate substances. Using the symbols of chemical elements and indices, the formulas of substances are written. The index shows how many atoms of a given element are included in the molecule of a substance. It is written at the bottom right of the sign of the chemical element. For example, the formulas of the substances mentioned above are written as follows: H 2 O, SO 2, CH 4, CO 2.

The chemical formula is the main iconic model in our science. It carries very important information for a chemist. The chemical formula shows: a specific substance; one particle of this substance, for example one molecule; qualitative composition substances, i.e. atoms of what elements are part of this substance; quantitative composition, i.e. how many atoms of each element are in a molecule of a substance.

The formula of a substance can also determine whether it is simple or complex.

Substances are called simple substances, consisting of atoms of one element. Compounds are made up of atoms of two or more different elements.

For example, hydrogen H 2, iron Fe, oxygen O 2 are simple substances, and water H 2 O, carbon dioxide CO 2 and sulfuric acid H 2 SO 4 are complex.

1. Which chemical element has a capital letter C? Write them down and say them.

2. From Table. 2 write out separately the signs of metal elements and non-metal elements. Say their names.

3. What is a chemical formula? Write the formulas for the following substances:

a) sulfuric acid, if it is known that its molecule contains two hydrogen atoms, one sulfur atom and four oxygen atoms;

b) hydrogen sulfide, the molecule of which consists of two hydrogen atoms and one sulfur atom;

c) sulfur dioxide, the molecule of which contains one sulfur atom and two oxygen atoms.

4. What unites all these substances?

Make three-dimensional models of the molecules of the following substances from plasticine:

a) ammonia, the molecule of which contains one nitrogen atom and three hydrogen atoms;

b) hydrogen chloride, the molecule of which consists of one hydrogen atom and one chlorine atom;

c) chlorine, the molecule of which consists of two chlorine atoms.

Write the formulas for these substances and read them.

5. Give examples of transformations when lime water is an analyte, and when it is a reagent.

6. Conduct a home experiment to determine starch in food. What reagent did you use for this?

7. On fig. 33 shows molecular models of four chemicals. How many chemical elements form these substances? Write down their symbols and say their names.

8. Take plasticine of four colors. Roll up the smallest white balls - these are models of hydrogen atoms, the larger blue balls are models of oxygen atoms, the black balls are models of carbon atoms, and finally the largest yellow balls are models of sulfur atoms. (Of course, we chose the color of the atoms conditionally, for clarity.) Using the atomic balls, make three-dimensional models of the molecules shown in fig. 33.

; 2) 9th Class. First part course... from high start with support...

  • The main educational program of primary general education of the Municipal Budgetary Educational Institution "Secondary School No. 7"

    Main educational program

    ... : physics, chemistry biology, geography... start, s 6.2-6.0 6.7-6.3 7.2-7.0 6.3-6.1 6.9-6.5 7.2-7.0 Running 1000 m Excluding time 2 CLASS... Program course of English to EMC "Enjoy English" for students 2 - 9 classes general educational institutions. ...

  • Public report of the state budgetary educational institution of the Samara region (1)

    public report

    ... . Chemistry 8-11 grade. Program course chemistry for 8-11 classes general educational institutions./author E.E. Minchenkov, T.V. Smirnova, L.A. Tsvetkov. M.: Bustard, 2008 Chemistry.Tutorial 8 class... , hiking in nature, "Funny starts", outdoor sports games that...

  • Guidelines for the course "Mathematics. Grade 2" / Arginskaya I. I., Kormishina S. N. Samara: Educational Literature Publishing House: Fedorov Publishing House, 2012. 336 p. (2)

    Guidelines

    Recommendations for the workbook "School start". Pedagogical diagnostics of starting readiness for ... A.O. Soroko-Tsyupy. 27. Gabrielyan O.S. Program course chemistry for 8-11 classes general educational institutions/ Gabrielyan O.S. - M.: Bustard, 2011. ...