Chemical properties of alkaline earth metals presentation. Alkaline earth metals (9th grade)
Element Ar Number of electrons in the last CO level Atomic radius Metallic properties Reduction properties Be9 2s2 +2)) Mg243s2+2))) Ca404s2+2)))) Sr885s2+2))))) Ba1376s2 +2)))))) Ra7s2+2))))))) General characteristics of the elements of the main subgroup of group II
Short electronic record - 2s22s2 2s22s2 2p62p6 2p62p6 3s23s2 3s23s2 3p63p6 3p63p6 4s24s2 3d03d0
General characteristics of the elements of the main subgroup of group II. The same structure of the outer electron layer. Elements exhibit CO +2. Atoms of elements are strong reducing agents, because they contain 2 electrons at the outer energy level, which give away during interactions with other elements. Atoms of elements are strong reducing agents, because they contain 2 electrons at the external energy level, which give away during interactions with other elements. With an increase in elements, the atomic radius increases, the number of electron layers increases, and therefore the ease of giving off electrons increases. Restorative properties increase in the group from top to bottom.
2Me 0 +O 2 2Me +2 O -2 Me 0 +H 2 Me +2 H 2 Me 0 +Cl 0 2 Me +2 Cl 2 Me 0 +S 0 Me +2 S -2 Me 0 +2HCl Me +2 Cl 2 + H 2 Me 0 +2HOH Me +2 (OH) 2 + H 2 Chemical properties of elements of group II of the main subgroup Chemical properties of elements of group II of the main subgroup
Alkaline earth metal compounds Alkaline earth metal oxides easily react with oxides of non-metals to form the corresponding salts. Alkaline earth metal oxides readily react with non-metal oxides to form the corresponding salts.
15
Compare the atoms of the elements by putting the signs or = instead of *: Compare the atoms of the elements by putting the signs or = instead of *: a) nuclear charge: Mg * Ca, Na * Mg, Ca * K; b) the number of electron layers: Mg * Ca, Na * Mg, Ca * K; Ca*K; c) the number of electrons at the outer level: Mg * Ca, Na * Mg, Ca * K; d) atomic radius: Mg * Ca, Na * Mg, Ca * K; e) reducing properties: Mg * Ca, Na * Mg, Ca * K. Ca * K. Knowledge test
Lesson type: learning new material.
Type of lesson: combined lesson
Lesson objectives:
Tutorials: the formation of students' knowledge about alkaline earth elements as typical metals, the concept of the relationship between the structure of atoms and properties (physical and chemical).
Developing: development of research skills, the ability to extract information from various sources, compare, generalize, draw conclusions.
Educators: nurturing a steady interest in the subject, cultivating such moral qualities as accuracy, discipline, independence, responsible attitude to the task assigned.
Methods: problematic, search, laboratory work, independent work students.
Equipment: computer, safety table, disk “Virtual laboratory in chemistry”, presentation .
During the classes
1. Organizational moment.
2. Introductory word of the teacher.
We are studying the section, metals, and you know that metals are of great importance in the life of a modern person. In previous lessons, we got acquainted with the elements of group I of the main subgroup - alkali metals. Today we are starting to study the metals of group II of the main subgroup - alkaline earth metals. In order to assimilate the material of the lesson, we need to remember the most important questions that were considered in the previous lessons.
3. Actualization of knowledge.
Conversation.
Where are the alkali metals in the periodic system of D.I. Mendeleev?
Student:
In the periodic system, alkali metals are located in group I of the main subgroup, on the outer level 1 electron, which alkali metals easily give away, therefore, in all compounds they exhibit an oxidation state of +1. With an increase in the size of atoms from lithium to francium, the ionization energy of atoms decreases and, as a rule, their chemical activity increases.
Teacher:
Physical Properties alkali metals?
Student:
All alkali metals are silvery-white in color with slight tints, light, soft and fusible. Their hardness and melting point naturally decrease from lithium to cesium.
Teacher:
We will check the knowledge of the chemical properties of alkali metals in the form of a small test work on the options:
- Ioption: Write the reaction equations for the interaction of sodium with oxygen, chlorine, hydrogen, water. Specify the oxidizing agent and reducing agent.
- I option: Write the reaction equations for the interaction of lithium with oxygen, chlorine, hydrogen, water. Specify the oxidizing agent and reducing agent.
- I I I option: Write the reaction equations for the interaction of potassium with oxygen, chlorine, hydrogen, water. Specify the oxidizing agent and reducing agent.
Teacher: The topic of our lesson is “Alkaline earth metals”
Lesson objectives: Give general characteristics alkaline earth metals.
Consider their electronic structure, compare physical and chemical properties.
Learn about the most important compounds of these metals.
Determine the scope of these compounds.
Our lesson plan is written on the board, we will work according to the plan, look at the presentation.
- The position of metals in the periodic system D.I. Mendeleev.
- The structure of the alkali metal atom.
- physical properties.
- Chemical properties.
- The use of alkaline earth metals.
Conversation.
Teacher:
Based on the previous knowledge, we will answer the following questions: next questions: To answer, we will use the periodic system of chemical elements of D.I. Mendeleev.
1. List the alkaline earth metals
Student:
These are magnesium, calcium, strontium, barium, radium.
Teacher:
2. Why are these metals called alkaline earth?
Student:
The origin of this name is due to the fact that their hydroxides are alkalis, and their oxides are similar in refractoriness to oxides of aluminum and iron, which previously bore the common name "earth"
Teacher:
3. Location of alkaline earth metals in PSCE D.I. Mendeleev.
Student:
Group II is the main subgroup. Metals of group II of the main subgroup have 2 electrons at the external energy level, located at a smaller distance from the nucleus than alkali metals. Therefore, their reducing properties, although great, are still less than those of the elements of group I. Strengthening of the reducing properties is also observed in the transition from Mg to Ba, which is associated with an increase in the radii of their atoms, in all compounds they exhibit an oxidation state of +2.
Teacher: Physical properties of alkaline earth metals?
Student:
Metals of group II of the main subgroup are silvery-white substances that conduct heat and electric current well. Their density increases from Be to Ba, while the melting point, on the contrary, decreases. They are much harder than alkali metals. All, except beryllium, have the ability to color the flame in different colors.
Problem: How are alkaline earth metals found in nature?
Why do alkaline earth metals mostly exist in nature in the form of compounds?
Answer: In nature, alkaline earth metals are in the form of compounds, because they have high chemical activity, which in turn depends on the features of the electronic structure of atoms (the presence of two unpaired electrons at the external energy level)
Fizkultminutka - rest for the eyes.
Teacher:
Knowing the general physical properties, the activity of metals, assume the chemical properties of alkaline earth metals. What substances do alkali metals interact with?
Student:
Alkaline earth metals interact with both simple and complex substances. They actively interact with almost all non-metals (with halogens, hydrogen, forming hydrides). From complex substances with water - forming water-soluble bases - alkalis and with acids.
Teacher:
And now, in experiments, we will verify the correctness of our assumptions about the chemical properties of alkaline earth metals.
4. Laboratory work on the virtual laboratory.
Target: carry out reactions confirming the chemical properties of alkaline earth metals.
We repeat the safety rules for working with alkaline earth metals.
- work in a fume hood
- on a tray
- with dry hands
- take in small quantities
We work with the text that we read in the virtual laboratory.
Experience No. 1. Interaction of calcium with water.
Experience number 2. Combustion of magnesium, calcium, strontium, barium
Write down the reaction and observation equations in a notebook.
5. Summing up the lesson, grading.
5. Reflection.
What do you remember about the lesson, what did you like?
6. Homework.
§ 12 exercise 1(b) exercise 4
Literature.
- Rudzitis G.E., Feldman F.G. Chemistry 9.- Moscow.: Education, 2001
- Gabrielyan O.S. Chemistry 9.-Moscow.: Bustard, 2008
- Gabrielyan O.S., Ostroumov I.G. Handbook of the teacher. Chemistry 9.-Moscow.: Bustard 2002
- Gabrielyan O.S. Control and verification work. Chemistry 9.-Moscow.: Bustard, 2005.
- Collection of the Virtual Laboratory. Educational electronic edition
Municipal Autonomous General Educational Institution
"Secondary School No. 24", Syktyvkar
PLAN - LESSON SUMMARY
TOPIC: Alkaline earth metals
Completed by: Malakhaeva Anna Lvovna
SYKTYVKAR, 2015
The purpose of the lesson:
To study the physical, chemical properties of alkaline earth metals;
Learn about the use of alkaline earth metals and their compounds.
lesson type - learning new material.
Critical Thinking Technology
Forms of organization of educational activities - frontal, steam room, individual.
Teaching methods :
Partially search;
Interdisciplinary conversation.
learning techniques :
independent / pair / individual work of students.
Tasks
I Tutorials:
Describe the physical properties of alkaline earth metals;
Acquaintance with the features of the chemical properties and areas of application of alkaline earth metals.
II Developing:
Development and generalization of students' knowledge about practical use SHCHZ metals;
III Educational :
Equipment:
Multimedia projector
for demonstration experiments: magnesium, hydrochloric acid, spoons for burning substances, matches, flasks filled with oxygen, test tubes;
instruction card "Application of alkaline earth metals and their compounds"
Literature for the teacher:
Kuznetsova N.E., Titova I.M., Gara N.N., Zhegin A.Yu. Chemistry: Grade 9: Textbook for students of educational institutions / Ed. N.E. Kuznetsova. – M.: Ventana-Graf, 2008.
Shatalov M.A., Kuznetsova N.E. Teaching chemistry. Solving integrative educational problems: Grades 8-9: Toolkit. – M.: Ventana-Graf, 2006.
Kuznetsova N.E., Shatalov M.A. Teaching chemistry based on interdisciplinary integration: 8-9 cells: educational method. Benefit. -M.: Ventana-Graf, 2006.
G.O. Astvatsaturov Technology of lesson goal-setting. - Volgograd: Teacher, 2009.
Materials of the workshop "Development of competence-oriented tasks in academic subjects" ANO "Center for Youth Development", Yekaterinburg.
During the classes
I organizational moment
Teacher greeting. Ready for the lesson. What do you see in the pictures. What unites them?(Slide 1). Metals.
II Actualization of knowledge
Let's remember everything we know about metals (“I know”). Metals are located in the lower left part of the PS, have a metallic luster, conduct electric current well, and also studied the properties of alkali metals(Slide 2). What haven't we learned yet? Supposed to be alkaline earth metals and a subgroup of aluminum. So what is the topic of today's lesson? alkaline earth metals (Slide 3). So what do we want to know? Physical properties, chemical properties and applications (Slide 4). The purpose of our lesson will be: 1. To study the physical, chemical properties of alkaline earth metals; 2. Learn about the use of alkaline earth metals (Slide 5).
Physical properties of alkaline metals. What physical properties do you think the alkaline earth metals will have?Assume: metallic luster, softness (similar to alkaline), low density. You have an instruction card on the tables. Read the text. What do they have in common? They are silver in color, and all are soft, except for beryllium.(Slide 6).
What determines the chemical properties of alkaline earth metals? The presence of 2 electrons in the outer energy level. What do you think the alkaline earth metals will react with? They can assume: with water, acids, oxygen.
Chemical properties of alkaline metals.
Let's look at the chemical properties. To do this, we will divide into three groups (by columns). Open §51 p.237. Column I will record the chemical properties with oxygen and with halogen using magnesium as an example. 2 Me + O 2 = 2 MeO (oxide),2Mg +O 2 = 2Mgo . Let's see how magnesium burns (demonstration experiment: combustion of magnesium (student shows)). Me + Hal 2 = MeHal 2 ( halides), Mg+Cl 2 = MgCl 2 .
II column - with sulfur and with nitrogen using calcium as an example. Me+S = MeS( sulfide), Sr+S =SrS; Me+N 2 = Me 2 N 3 ( nitride), Sr + N 2 = Sr 2 N 3 . III column - with hydrogen and with water using calcium as an example. Me + H 2 = MeH 2 (hydride),Ca + H 2 = Ca H 2 ; Me + 2H 2 O =M e(Oh ) 2 + H 2 , Ca + 2H 2 O =Ca (Oh ) 2 + H 2 .
Still SHCHZ metals will interact with acids. Let's see how magnesium will interact with hydrochloric acid (demonstration experience: the interaction of magnesium with acid (student shows)). Attention to the slide! Me + acids = salt +H 2 (Slide 7). What products are formed as a result of the reaction? Magnesium chloride and hydrogen is released.Mg + 2HCl = MgCl 2 + H 2.
Finding alkaline earth metals in nature and compounds of alkaline earth metals. Where do you think pure alkaline earth metals can be found in nature? Nowhere, because in its pure form, they are not found due to their high chemical activity. There are papers on your tables. Scan the text with your eyes (15 seconds). Now I am showing you a picture, and you, using the text that is on your tables, will tell you where this metal is found and used. Answer using the text on the tables(Slides 8-9).
III Consolidation
Today we have studied alkaline earth metals. What did you learn about them? Did you achieve the goal you set at the beginning of the lesson? Yes, we have, we have learned their physical and chemical properties, their presence in nature and their application(Slide 10). And now "Fill in the blanks!" (Slide 11). Homework. §51; prepare about the history of the discovery of alkaline earth metals according to options: I option - Be , II option - mg , III option - Ca , IV option - Sr , V option - Ba , VI option - Ra (Slide 12).
Instructional card "Physical properties, application and finding of alkaline earth metals and their compounds"
Beryllium- solid metal of light gray color. It occurs in nature in the form of minerals: beryl, chrysoberyl and their varieties: emerald, aquamarine, alexandrite - known as precious stones. Beryllium and its water-soluble compounds are highly toxic (poisonous). Even a negligibly small admixture of it in the air leads to serious illnesses. It finds wide application in technology. Added to copper, it greatly increases its hardness, strength, chemical resistance, and makes it look like steel. The main consumer of beryllium is nuclear power. The need for it is growing every year.
Magnesium - soft, silvery-white metal. B It was first obtained by Devi in 1808 from white magnesia (magnesite MgCO 3) - a mineral found near the Greek city of Magnesia. By the name of the mineral, they gave the name to a simple substance and a chemical element. Magnesium sulfate (one of the common magnesium salts) is also called bitter salt - it gives sea water a bitter taste. This magnesium salt is used as a laxative. Alloys with magnesium are stronger, harder, easily polished, processed and used in the automotive industry, aviation, and rocket technology.
Calcium - soft silvery white. It ranks fifth in terms of prevalence. It was also first obtained by Devi in 1808. The name of the element comes from the Latin word "cals", which means "lime, soft stone". It occurs in the form of calcite (calcite forms deposits of chalk, marble, limestone), as well as in the form of the mineral gypsum, which is a crystalline hydrate. It is used in construction, in medicine for applying plaster bandages, for making casts. Calcium is also found in human bones and teeth.
Strontium- soft, malleable and plastic silver-gold color. It is less common in the form of the mineral celestine, which means "heavenly" in Latin - strontium sulfate, formed by pink-red, pale blue crystals. It (strontium) got its name from the name of the Scottish village of Strontian, near which a rare mineral strontianite SrCO 3 was found at the end of the 18th century. The main areas of application of strontium and its chemical compounds are the radio-electronic industry, pyrotechnics, metallurgy
Barium- soft silver-white metal. It occurs in the form of barite BaSO 4 (“baris” - heavy from Latin). It is used for the manufacture of radio lamps, in leather business (to remove wool), in sugar production, for the preparation of photographic paper, and for the smelting of special windows. BaSO 4 due to its insolubility and ability to delay x-rays is used in x-ray diagnostics - barite porridge.
Radium- Shiny silver-gold metal.
Used for the manufacture of luminous paints of constant glow (for marking the dials of aviation and marine instruments, special watches and other instruments).
Fill in the blanks!
Ca + ... = 2CaO
… + … = Be 3 N 2
Mg + ... = MgSO 4 + ...
To use the preview of presentations, create an account for yourself ( account) Google and sign in: https://accounts.google.com
Slides captions:
alkaline earth metals
Position in the periodic table. In the periodic system, they are in the main subgroup of group II. They are strong reducing agents, they give 2 ē, in all compounds they show an oxidation state of +2. General configuration of external energy level nS ² Mg +12 2 ē , 8 ē , 2 ē Ca +20 2 ē , 8 ē , 8 ē , 2 ē Sr +38 2 ē , 8 ē , 18 ē , 8 ē , 2 ē Ba +56 2 ē , 8 ē , 18 ē , 18 ē , 8 ē , 2 ē
Position in the periodic table Be Mg Ca Sr Ba Ra Reducing properties are enhanced
Atomic structure +4)) +12))) +20)))) +38))))) +56)))))) Be Mg Ca Sr Ba 2 2 2 2 2
Physical properties of alkaline earth metals Alkaline earth metals are silver-white, solid substances. Compared with alkali metals, they have higher t°pl. and t ° boiling., ionization potentials, densities and hardness. Beryllium (Be) is a very hard material and can scratch glass; the hardness of other elements of the subgroup decreases, and barium is close in hardness to lead
Physical properties of alkaline earth metals. Values Be Mg Ca Sr Ba Ra Ρ g/cm 1.85 1.737 1.54 2.63 3.6 6 T pl. ° according to C 1287 648 842 768 727 969
Physical properties flame color þ t melting 1.74 g / cm 3 651 C 0 1.54 g / cm 3 851 C 0 2.63 g / cm 3 770 C 0 3.76 g / cm 3 710 C 0 Mg Ca Sr Ba
Occurrence in nature Beryllium: 3BeO Al2O3 6SiO2 - beryl Magnesium: MgCO3 - magnesite Calcium: CaCO3 MgCO3 - dolomite KCl MgSO4 3H2O - kainite KCl MgCl2 6H2O - carnallite CaCO3 - calcite (limestone, marble, chalk) Ca3 (PO4) 2 - apatite, phosphorite CaSO4 2H2O - gypsum CaSO4 - anhydrite CaF2 - fluorspar (fluorite) Strontium: SrSO4 - celestite SrCO3 - strontianite Barium: BaSO4 - barite BaCO3 - witherite
Chemical properties With simple substances (non-metals) 2Me 0 + O 2 → 2Me +2 O -2 - oxide Me 0 + H 2 → Me +2 H 2 - hydride Me 0 + Cl 0 2 → Me +2 Cl 2 - chloride Me 0 + S 0 → Me +2 S -2 - sulfide 2. With complex substances Me 0 + 2HCl → Me +2 Cl 2 + H 2 Me 0 + 2HOH → Me +2 (OH) 2 + H 2
Compounds of alkaline earth metals Oxides of alkaline earth metals - MeO, are basic in nature, easily react with oxides of non-metals to form the corresponding salts.
BaSO 4 Due to its insolubility and ability to delay x-rays, it is used in x-ray diagnostics - barite porridge.
Ca 3 (PO 4) 2 Included in phosphorites and apatites, as well as in bones and teeth. The body of an adult contains 1 kg of Ca in the form of calcium phosphate.
CaCO 3 Calcium carbonate is one of the most common compounds on Earth. It is contained rocks- chalk, marble, limestone.
CaSO 4 ∙ 2H 2 O Occurs in nature in the form of the mineral gypsum, which is a crystalline hydrate. It is used in construction, in medicine for applying plaster bandages, for making casts.
MgCO 3 is widely used in the production of glass, cement, bricks, as well as in metallurgy to convert waste rock into slag.
Ca (OH) 2 Calcium hydroxide or slaked lime with sand and water is called lime mortar and is widely used in construction. When heated, it decomposes into oxide and water.
alkaline earth metals
Compiled by: teacher MOKU "Kitaevskaya secondary school"
Trubinova E.L.
- Generalize and systematize knowledge about alkaline earth metals
- Be able to characterize elements by position in the periodic table
- Know the physical and chemical properties
- Know the use of alkaline earth metal compounds
Position in the periodic system. The structure of the atom
Alkaline earth metals in the periodic system are in the main subgroup of group II.
They are strong reducing agents, they give 2 ē, in all compounds they show an oxidation state of +2.
Mg +12 2 ē , 8 ē , 2 ē
Ca +20 2 ē, 8 ē, 8 ē, 2 ē
Sr +38 2 ē , 8 ē , 18 ē , 8 ē , 2 ē
Ba +56 2 ē, 8 ē, 18 ē, 18 ē, 8 ē, 2 ē
Physical Properties
flame color ρ t melting
1.74g/cm 3 651 C 0
1.54 g/cm 3 851 C 0
2.63g/cm 3 770 C 0
3.76g/cm 3 710 C 0
Chemical properties
2Me 0 +O 2 → 2Me +2 O -2
Me 0 +H 2 → Me +2 H 2
Me 0 +Cl 0 2 → Me +2 Cl 2
Me 0 +S 0 → Me +2 S -2
Me 0 +2HCl → Me +2 Cl 2 + H 2
Me 0 +2HOH → Me +2 (OH) 2 + H 2
Alkaline earth compounds metals
Alkaline earth metal oxides readily react with non-metal oxides to form the corresponding salts.
BaSO 4
Due to its insolubility and ability to retain x-rays, it is used in x-ray diagnostics - barite porridge.
Ca 3 (PO 4 ) 2
Included in the composition of phosphorites and apatites, as well as in the composition of bones and teeth. The body of an adult contains 1 kg of Ca in the form of calcium phosphate.
CaCO 3
Calcium carbonate is one of the most widespread compounds on Earth. It contains rocks - chalk, marble, limestone.
Occurs in nature in the form of the mineral gypsum, which is a crystalline hydrate. It is used in construction, in medicine for applying plaster bandages, for making casts.
CaSO 4 ∙ 2H 2 O
Occurs in nature in the form of the mineral gypsum, which is a crystalline hydrate. It is used in construction, in medicine for applying plaster bandages, for making casts.
MgCO 3
It is widely used in the production of glass, cement, brick, as well as in metallurgy to convert waste rock into slag.
Ca(OH) 2
Calcium hydroxide or slaked lime with sand and water is called lime mortar and is widely used in construction. When heated, it decomposes into oxide and water.
Check of knowledge
Compare element atoms by putting signs or = instead of *:
a) nuclear charge: mg * Ca , Na * mg , Ca * TO;
b) number of electron layers: mg * Ca , Na * mg ,
Ca * TO;
V) number of electrons in the outer level:
mg * Ca , Na * mg , Ca * TO;
d) atomic radius: mg * Ca , Na * mg , Ca * K ;
e) restorative properties: mg * Ca ,
Na * mg , Ca * K .
check yourself (independent work)
Complete the schemes of interaction of alkaline earth metals with nonmetals with general formulas and names of reaction products.
Write down the specific reaction equations, placing the coefficients in them using the electronic balance method:
a) M + S b) M + N 2
c) M + H 2 d) M + C1 2
Example: ___________________ Example: _____________________
Add the reaction equations:
a) Ca + H 2 O → ……………………….
b) Mg + HC l →……………………….
c) Ba + O 2 →………………………..
Carry out transformations according to the scheme:
Me → Meo → Me(OH) 2 → MeSO 4
Homework:
§ 12. ex. No. 5, 8
Write reaction equations with the help of which you can carry out any two transformations from those compiled by students in the lesson.
Used Books
- Rudzitis G.E., Feldman F.G. Chemistry 9.- Moscow.: Education, 2001
- Gabrielyan O.S. Chemistry 9.-Moscow.: Bustard,
- Gabrielyan O.S., Ostroumov I.G. Handbook of the teacher. Chemistry 9.-Moscow.: Bustard 2002
- Collection of the Virtual Laboratory. Educational electronic edition