Cheatsmetals and metal materials
Scroll. 1.The main types of questions examined in this topic are multiple-choice questions, fill-in-the-blank questions and ** questions. The high school entrance examination will combine the latest technology in metal materials with relevant knowledge to design corresponding comprehensive questions, so that students can make inferences and inferences through analysis. With the continuous advent of various new metal materials, the test questions of "new metals" combined with the knowledge learned will become the trend of propositions in the future.
2.The chemical properties of metals are the hot spots and focus of the high school entrance examination, and there are various forms of examination; Since the examination of the properties of metals is easy to combine the knowledge of acids, alkalis, salts, etc., it is necessary to pay attention to the horizontal connection between the knowledge while mastering the knowledge of this lecture. The nature of metals largely determines their use. Topics often reflect the use of a specific substance through diagrams and textual information, and test the grasp of the properties of the substance involved. During the review, summarize and compare the phenomena, products and chemical equations of the reaction of metals with oxygen, acid, and salt solutions to find out their similarities and differences.
3.The application of the order of metal activity, combined with the reaction of metals with acids and salt solutions, the image questions examine the degree of reaction of the substance, the sequence and the remaining ions in the solution, and the final substance generated. Knowing the sequence of metal activity and understanding the precautions in application is the key to the conclusion. This kind of test questions are generally more difficult, focusing on students' ability to acquire, process and flexibly use the chemistry knowledge they have learned to analyze and solve problems. When answering, you can read the meaning of the question, extract useful information, and at the same time connect with the content of the textbook and apply it comprehensively, so that the problem can be easily solved.
The basics. 1. Metal materials
Classification
Physical properties
Special reminder] Iron can be attracted to magnets, and this property can be used to distinguish iron from other metal elements.
The best of metal
Aluminum, the most abundant metallic element in the earth's crust;
Calcium, the most abundant metallic element in the human body;
Iron is currently the metal with the highest annual production in the world;
The metal with the best electrical and thermal conductivity - silver;
Tungsten, the metal with the highest melting point;
The metal with the lowest melting point – mercury.
alloys
A substance with metallic properties formed by the fusion of one metal with one or more other metals (or metals and non-metals). (Note: Mixture).
Generally speaking, the melting point of the alloy is lower than that of each component, the hardness is greater than that of each component, and the corrosion resistance is better.
Note: Titanium and titanium alloys: Considered to be important metal materials in the 21st century, titanium alloys have good "compatibility" with the human body, so they can be used to make artificial bones, etc.
Advantages: (1) high melting point, small density (2) good plasticity, easy processing, good mechanical properties (3) good corrosion resistance.
ApplicationAlloys and pure metals can be identified by comparing the hardness of alloys and pure metals: after depicting each other, the scratches are pure metals, and the ones that do not change in any way.
Second, the chemical properties of the metal
Metals react with oxygen
1) Regularity: Metal, Oxygen, Metal Oxide.
2) Most metals can react with oxygen, but the difficulty and intensity of the reaction are different, mainly related to the activity of the metal.
3) Common reaction of metals with oxygen.
[Special Reminder].Aluminum's good corrosion resistance is not due to its chemical stability, but because aluminium reacts with oxygen at room temperature to form a dense alumina film covering the surface of aluminum, preventing further oxidation of aluminum.
The metal reacts with hydrochloric acid and dilute sulfuric acid
1) Regularity: metallic acid, salt, hydrogen (displacement reaction).
2) The conditions under which the reaction takes place: the activity of the metal must be ranked before hydrogen.
3) The phenomenon and chemical equation of the reaction of magnesium, zinc and iron with acids.
[Special Reminder].When iron is replaced with dilute hydrochloric acid or dilute sulfuric acid, copper sulfate and other solutions, ferrous ions are formed.
Fe2), the color of the solution changes to light green. After the metal reacts with the acid, the mass of the solution increases.
The metal reacts with a saline solution
1) Rules: metals, salts, new salts, new metals.
2) The conditions under which the reaction occurs.
It must be the front metal replacing the back metal (except K, CA, NA).
The salt must be soluble in the reaction.
3) Common metals react with salt solutions.
Displacement reaction
1) Definition: The reaction of one element with one compound to produce another element and another compound.
2) Characteristics: There must be elements with valency changes in the displacement reaction.
3) General formula: a bc===ac b.
[Special Reminder].The displacement reaction must have elemental and compound formation, but the reaction with elemental and compound formation is not necessarily a displacement reaction, such as.
co＋cuo
co2＋cu。