Knowledge Points
1, the role of symbols: can be simple and clear representation of things, but also to avoid confusion due to the different words and different shapes of things caused by the different faces.
2, the composition and composition of matter.
(1) water is a substance composed of water molecules, water molecules are composed of hydrogen and oxygen atoms.
(2) Sodium chloride is made up of oxygen and sodium ions.
(3) Silicon is made up of silicon atoms.
(4) Water is made up of the elements hydrogen and oxygen, sodium chloride is made up of the elements sodium and chlorine, and silicon is made up of the element silicon.
3. Molecules are a kind of particles that make up matter and maintain its chemical properties, and atoms are the smallest particles in chemical changes. Ions are electrically charged atoms or groups of atoms.
4, atomic structure: atom
(1) in the atom: nuclear charge = number of protons = number of electrons outside the nucleus.
(2) In atomic structure, not all atoms have neutrons in the nucleus, e.g., hydrogen atom.
(3) Because the number of nuclear charges (i.e., protons) is equal to the number of electrons outside the nucleus and the electrical properties are reversed, atoms are not electrically active.
(4) In the atomic structure, electrons occupy a large amount of space and have a small mass, so they are negligible.
(5) In the atomic structure, the nucleus occupies very little space, but the mass of the atom is concentrated in the nucleus.
5, isotopes of atoms:
(1) The concept of prime elements: a general term for similar atoms with the same number of nuclear charges (i.e., number of protons).
(2) the concept of isotope atoms: the same nuclear charge, the number of neutrons is not the same as the same type of atoms.
6, according to the number of elements that make up the substance, can be divided into monomers and compounds of pure matter, composed of an element of pure matter for the monomers, composed of a variety of elements of pure matter for compounds.
7, the types of elements:
8, the classification of elements: the earth's crust in order of elemental content from high to low oxygen, silicon, aluminum, iron.
9, the significance of the element symbols
10, the periodic table of the elements is the atomic number that the number of protons from small to large, each horizontal that is, each cycle of the elements are arranged in accordance with the order of the metal elements → non-metallic elements → rare gases, each column of the chemical properties of the elements are very similar.
11. (1) A chemical formula is a formula that expresses the molecular composition of a substance using elemental symbols.
(2) the meaning of the chemical formula: "H2O", for example, ① that water; ② that a water molecule; ③ that water consists of hydrogen and oxygen elements; ④ that a water molecule is composed of two hydrogen atoms and one oxygen atom.
(3) The chemical formula of a compound is written in terms of valency, in which the algebraic sum of the positive and negative valency of the element is zero. Mime the chemical valences of the elements you know. Slightly.
12, relative atomic mass = × 12 = number of protons + number of neutrons.
13, according to the chemical formula: "H2O" as an example.
(1) relative molecular mass = the sum of the relative atomic mass of each element × the number of atoms. For example, the relative molecular mass of water: M = 1 × 2 + 16 = 18.
(2) Calculate the mass ratio of each element. For example, the mass ratio of hydrogen and oxygen in water H:O = 1 × 2:16 = 1:8.
(3) Calculate the mass fraction of each element. For example, the mass fraction of hydrogen in water H% = = = = ≈11.1%.
(4) Calculate the mass of each element M element = M substance x mass fraction of element. E.g. What is the mass of elemental hydrogen in 18 grams of water?
MH = 18 grams × = 18 grams × = 2 grams.
Chapter 2 Air and Life
Knowledge Points (a) Air
1. Air is a mixture of several monomers and several compounds.
2. Composition of air (volume ratio)
3. Utilization of air.
(1) Nitrogen is the main element that makes up the proteins of living organisms.
Uses of Nitrogen
(2) Rare gases: very stable chemically, various colored light can occur when electrified.
Uses
(2) Oxygen and oxidation
1. Physical properties of oxygen.
2. Chemical properties of oxygen: for respiration, support combustion, more active chemical properties, oxidizing.
(1) sulfur combustion in oxygen:
Ignition
S + O2 ====== SO2, burning bright blue-purple flame, release a lot of heat, produce a colorless gas with an irritating odor.
(2) Combustion of iron in oxygen:
Ignition
3Fe + 2O2======Fe3O4, which burns with sparks, gives off a lot of heat, and produces a black solid.
3, oxidation reaction: a chemical reaction in which a substance reacts with oxygen.
4, the use of oxygen.
5. Production of oxygen.
(1) Laboratory production.
① laboratory commonly used decomposition of hydrogen peroxide or heating of potassium permanganate or heating of potassium chlorate and manganese dichloride mixture to produce, the chemical equation of the reaction are:
Mn O2
2H2O2======2H2O + O2↑
△
2KMn O4======K2MnO4 + Mn O2 + O2↑
Mn O2
2KclO3======2KC1 + 3O2↑
△
②The diagrams of the experimental setups are shown in Fig. 2-20-1 A and B, respectively.
Figure 2-20-1
③Collection method
(2) Industrial production method: Separation of air method.
6, catalyst
7, fire suppression and fire self-help.
(1) combustible combustion conditions
(2) fire extinguishing methods
(3) fire self-rescue and measures.
Example 1: Compare and contrast the similarities and differences between the phenomena of combustion, explosion (meaning chemical explosion), and spontaneous combustion.
Doing it Figure 2-20-2 shows a diagram of a laboratory setup for the production of oxygen, answer the following questions.
(1) Write the name of the apparatus with the symbol: Figure 2-20-2
a: alcohol lamp b: iron stand c: gas cylinder d: sink
(2) If potassium permanganate is used to make oxygen, a slight improvement to the apparatus in the diagram should be the addition of a cotton ball at the mouth of the test tube, to prevent the KMnO4 powder from entering the conduit with O2.
(3) When assembling the apparatus, the gas-conducting tube should not be extended too far into the test tube, for the reason that when it is too long, it is not easy for the gas to be discharged, and it may even make the gas produced impure.
(4) The most appropriate moment to start collecting oxygen bubbles from the cylinder is when the bubbles are continuously and evenly (rapidly) expelled.
(5) When bubbles are seen coming out of the cylinder, it is proved that the cylinder is full of oxygen. Cover the mouth of the cylinder with a piece of glass under water and carefully move the cylinder out of the water, and the cylinder should be placed squarely on the table top, this is because the density of oxygen is greater than that of air.
(C) Chemical Reactions and Conservation of Mass
1. Chemistry and decomposition reactions.
(1) Chemistry reaction: A + B → C.
(2) Decomposition reaction: A → B + C.
2. Law of conservation of mass.
(1) Meaning: the sum of the masses of the substances participating in a chemical reaction is equal to the sum of the masses of the substances produced after the reaction, this law is called the law of conservation of mass.
(2) Explanation of conservation of mass.
Before and after a reaction
(3) Quantities that must remain the same before and after a chemical reaction
3. Chemical equation.
(1) Definition: a chemical equation used to represent a chemical reaction.
(2) Principles of writing chemical equations.
(3) Methods and steps for writing chemical equations. .............................. .............................. .............
(4) Significance expressed by chemical equations.
① indicates the types of reactants and products
② indicates the conditions of the reaction
③ indicates the ratio of the number of atoms and molecules between the reactants and products
④ indicates the ratio of the masses between the reactants and products
4. Calculations based on the chemical equation.
(1) According to the chemical equation: the chemical equation can express the reactants, products of the mass ratio between the substances.
(2) Calculation steps.
Set the unknown quantity → write the chemical equation → write the relative molecular mass of the substance concerned and the known quantity → list the equation → write a concise solution → answer
Example 2 R combustion in O2 text expression for R + oxygen ignition carbon dioxide + water, the composition of R is correctly described ( )
A. contains only C, H elements B. must contain C, H B. It must contain C and H elements and may contain oxygen elements
C. It must contain C, H and O elements D. It must contain C and O elements and may contain H elements
Analysis According to the law of conservation of mass, the process of a chemical reaction is the process of atoms in the molecules of a reactant reassembling themselves into molecules of a product, and the type and number of atoms before and after the reaction do not change nor do they increase or decrease. By the products of CO2 and H2O can be known to participate in the reaction of the material in the C, H, O three elements, and R combustion O2 to participate in the reaction, so there is no oxygen in the R element, combustion products may be generated in CO2 and H2O, so can only be sure that the R C, H elements, oxygen element whether or not to determine the presence of the element can not be determined.
Answer B.
Do the following statements are correct
A, 3 grams of carbon in 10 grams of oxygen combustion, can produce 13 grams of carbon dioxide
B, 3 grams of carbon in 19 grams of oxygen combustion, can produce 15 grams of carbon dioxide
C, 3 grams of carbon in 8 grams of oxygen combustion, can produce 11 grams of carbon dioxide
D, 6 grams of carbon burned in 10 grams of oxygen produces 16 grams of carbon dioxide
Knowledge Points (II)
I. Respiration in living things
1. Structure of the human respiratory system and gas exchange.
(1) Components of the respiratory system.
(2) Respiratory movements.
(3) Changes in air pressure in the alveoli.
2. Respiration in animals.
Animals, like humans, breathe, inhaling oxygen and exhaling carbon dioxide.
3. Plant respiration.
There is also an exchange of gases between plants and the air, and they also breathe, also inhaling oxygen and exhaling carbon dioxide.
II. Photosynthesis
1.
(1) Photosynthesis is the process by which green plants, under the action of sunlight, use carbon dioxide and water-based substances to make organic matter such as starch and release oxygen .
(2) The reaction process of photosynthesis can be expressed as follows:
Light
Carbon dioxide + water organic matter (starch) + oxygen.
Chloroplasts
(3) The essence of photosynthesis is: synthesizing organic matter and storing energy.
(4) The significance of photosynthesis:
① photosynthesis provides food for all living things; ② photosynthesis provides energy for all living things; ③ photosynthesis provides oxygen for all living things.
2. Carbon dioxide.
(1) Carbon dioxide laboratory production.
①Reaction principle: CaCO3 + 2HCl====CaCl2 + H2O + CO2↑.
② collection method: upward air exhaust method.
③Method of checking the fullness: a burning stick of wood is placed at the mouth of the collecting cylinder.
(2) Physical properties of carbon dioxide.
(3) Chemical properties of carbon dioxide.CO2
(4) Uses of carbon dioxide.
3. photosynthesis and respiration.
(1) Photosynthesis and respiration are just the opposite of the two processes, the difference between the two is compared as follows:
Photosynthesis Respiration
①Photosynthesis is carried out inside the chloroplasts of plants
②Can only be carried out under light
③Exhale carbon dioxide, give off oxygen
④Manufacture of organic matter, storage of energy ①Plant All viable parts of the plant can carry out
② With light and without light
③ Take in oxygen, give out carbon dioxide
④ Decompose organic matter, release energy
(2) The link between photosynthesis and respiration.
Photosynthesis provides substances (organic matter and oxygen) for respiration, and respiration provides raw materials for photosynthesis, which are interdependent and antagonistic.
Doing a Laboratory production of carbon dioxide, the choice of reactants is best ( )
A. sodium carbonate and dilute sulfuric acid B. limestone and dilute sulfuric acid C. marble and dilute hydrochloric acid D. limestone and concentrated hydrochloric acid
Solutions A in the reaction rate is too fast, it is difficult to control; B in the reaction to produce a slightly water-soluble CaSO4 covered in the surface of the limestone, preventing the reaction; D concentrated HCl is volatile, can volatilize hydrogen chloride gas, resulting in the generation of impure gas; only C reaction to produce CO2 moderate speed, convenient source of raw materials, cheap.
Answer C
Do One Plants convert light energy through photosynthesis and finally store it in ( )
A. Chloroplasts B. Starch C. Oxygen D. Chlorophyll
Three, the cycle of oxygen and carbon in nature.
1. The cycle of oxygen in nature.
(1) The way nature produces oxygen: photosynthesis in plants.
(2) The way nature consumes oxygen
2. The cycle of carbon in nature.
(1) Pathways by which carbon dioxide is produced in nature
(2) Pathways by which carbon dioxide is consumed in nature: photosynthesis in plants.
3. Protect the ozone layer.
(1) The role of the ozone layer: blocking and weakening the excessive ultraviolet rays from the sun, and providing protection for living things.
(2) Destruction and protection of the ozone layer.
(1) Causes of the destruction of the ozone layer: the action of substances such as chlorofluorocarbons on ozone.
(2) the protection of the ozone layer: ban the production and use of chlorofluorocarbon-containing refrigerants, blowing agents, detergents, sprays and other chemical substances.
4, the greenhouse effect.
(1) The greenhouse effect is the insulation of the earth by greenhouse gases such as carbon dioxide.
(2) the benefits of the greenhouse effect: moderate greenhouse effect can ensure the stability of the temperature on the earth, is conducive to the survival of animals and plants.
(3) The bad side of the greenhouse effect: excessive greenhouse effect can lead to global warming, sea level rise, etc.
Four, air pollution and protection
1, air pollution.
(1) Factors causing air pollution.
(2) Types of air pollution.
2. Protection of air.
(1) Clean air ensures the healthy and normal growth of living things on earth.
(2) Measures to protect the air.
Example 2 The main cause of the following phenomena is related to the emission of SO2 (A)
A.Acid rain B.Photochemical smog C.Ozone hole D.Greenhouse effect
Solution The four discrete options in this question all belong to the phenomena in terms of atmospheric pollution, but they are formed for different reasons. Photochemical smog is related to hydrocarbons, carbon monoxide and nitrogen oxides; the ozone hole is related to hydrochlorofluorocarbons (that is, Freon); the greenhouse effect is related to the rising levels of carbon dioxide in the atmosphere; acid rain is acidic precipitation with a pH of less than 5.6, and an increase in the number of acidic pollutants in the atmosphere, such as sulfur dioxide, is the main reason for the production of acid rain. Therefore, the answer is A.
Example 3 Unrelated to the oxygen cycle is ( )
A. Respiration of organisms B. Combustion of substances C. Photosynthesis D. Destruction of the ozone layer by Freon
Solution This question examines the specific process of the oxygen cycle. Oxygen is constantly being consumed and produced to keep the level of oxygen in the atmosphere constant. Oxygen consumption includes respiration of plants and animals, decomposition of microorganisms (also respiration), and combustion of fossil fuels; oxygen production is mainly the result of plant photosynthesis.
Answer D.
Doing it According to the principle of the oxygen cycle, the following methods are unlikely to freshen the air (D)
A. Opening windows B. Putting more flowers and plants on the balcony C. Installing a ventilating fan D. Spraying air fresheners
Chapter 3 Plants and Soil
Knowledge Points
1. Structure of soil.
(1) Composition:
Soil ----
(2) Formation of Soil:
1) Mineral particles: weathering products of rocks.
Rock *** with the action of breaking into small particles
② humus (organic matter): rock weathering so that the surface of the earth's crust there is an accumulation of mineral particles, for the growth of lower plants. The first lichens grew on land, excrement and dead organisms into the mineral particles to form humus.
(3) Soil formation is: a long, ongoing process that is still going on today.
(3) Structure and types of soil:
①Soil is composed of mineral particles, humus, water and air.
Mineral particles
The coarser the mineral particles, the larger the inter-particle spaces, the better the aeration, the higher the content of air, the weaker the water retention, the water permeability , and vice versa.
②The classification of soil.
Soil ----
(4) Recovery properties of soil and plant growth:
Types of soil Condition of soil Plant growth condition and causes Volume fraction of soil constituents
Sand soils Loose, not easy to be cohesive, aeration and permeability, easy to be drought-prone, fast decomposition of organic matter, easy to be lost Plants are not suitable for growth. Due to strong water permeability, weak fertilizer retention, resulting in poor growth or death of plants due to insufficient water and fertilizer Solids less than 50%, the proportion of air is significantly greater than the proportion of water, and the proportion of water is relatively small
Clay soils Sticky when wet and hard when dry, strong water and fertilizer retention, poor aeration and permeability Plants are not suitable for growth due to poor aeration, resulting in the inability of the roots of plants to breathe normally Solids volume is greater than 50%, and the proportion of water is greater than the proportion of air, and the proportion of moisture is greater than the proportion of water. The proportion of water is greater than that of air, and the proportion of air is smaller
Loamy soil Not too loose, not too sticky, better aeration and permeability, and better water and fertilizer retention Plants are suitable for growth, and there is sufficient water, air, and inorganic salts in the soil The solid volume accounts for about 50% (of which organic matter accounts for 1% to 5%), and the water and air each account for 1/4
2.
3. Soil pollution and its prevention.
(1) the causes of soil pollution:
① industrial "three wastes" arbitrary emissions;
② pesticides and fertilizers used in large quantities;
③ domestic sewage discharge;
④ arbitrary disposal of domestic waste, piling up, resulting in soil "white pollution";
5) Domestic sewage, garbage, and hospital discards contain germs, parasites, and viruses, which can biologically pollute the soil.
(2) measures to prevent and control soil pollution;
①control of industrial "three wastes" arbitrary emissions;
②promote biological control of agricultural pests and diseases, insect pests, organic fertilizers instead of chemical fertilizers;
③ harmless treatment of domestic sewage (for example: oxidation pond treatment);
4 domestic sewage treatment (for example: oxidation pond treatment)
④ Classification of domestic garbage for recycling and utilization.
VIII, plant body
1, roots.
(1) function: with the function of fixation and absorption.
(2) Root system ----
(3) Root tip: It is the main part of the root to absorb water, it consists of root hair area, elongation area, meristematic area and root crown.
(4) Causes of water absorption and loss in plant cells: if the mass fraction of the plant cell cytosol is greater than that of the external solution, the plant cell absorbs water; conversely, the plant cell loses water.
2. Stem.
(1) Function: with the function of support and transport.
(2) type: according to the growth of different types, stems can be divided into four categories of erect stems, winding stems, climbing stems, stolons, of which the most common is the erect stems.
(3) the structure of the stem: from inside to outside for the pith, xylem, the formation layer, the bast layer, epidermis and so on. Among them, the xylem has ducts that transport water and inorganic salts; the phloem has sieve tubes that transport organic matter.
(4) Annual rings: the dividing line between the fall timber of the previous year and the spring timber of the following year when the stem is growing. Outside the temperature is suitable, sufficient moisture, stem growth fast, lax arrangement, lighter color; the opposite growth is slow, tight arrangement, darker color.
(5) Experiment: observe the structure of the stem of dicotyledonous plants.
①Blue cobalt chloride filter paper turns red in contact with water, so it must be sealed and stored;
②The stem is stained with green outer bark, green sieve tubes, red xylem and green pith.
3, leaves.
(1) Function: leaves have two functions: photosynthesis and transpiration.
(2) leaf upper and lower epidermis in the stomata, stomata is the leaf water transpiration channel, gas in and out of the portal. Stomata consist of two half-moon shaped defense cells.
(3) Transpiration.
①meaning: water in the plant is vaporized and removed from the stomata. 99% of the water absorbed by roots is used for transpiration.
(2) Role
Chapter 4 Electricity and Points of Knowledge
Chapter 4 Electricity and Points of Knowledge