The chemistry of the third year of junior high school is just sorting, and the basics of chemistry i

First of all, answer the first question, molecules, atoms, ions, which are all microscopic ways to understand the form of matter. To be precise, the atom can be considered to be the most basic unit of various elements in nature, which is composed of the nucleus and the outer orbital electrons (also known as bound electrons or circumferential electrons); A molecule is made up of atoms, which can be made up of atoms of the same kind, as you call the elemental metal (k, na, fe......Oxygen (O2), diamond (C), and molecules can also be composed of multiple atoms, such as carbon dioxide (CO2) and water (H2O), which are the smallest particles that exist independently and maintain the chemical properties of matter; Ions, on the other hand, are obtained by molecules (i.e., electrolytes) that can be ionized under certain conditions (e.g., dissolved in certain solvents, heated and melted, etc.), such as hydrogen ions H+, acid ions (sulfate SO42-, carbonate CO32-......).Wait a minute.

The second question is that a pure substance refers to a single substance, which is defined as a substance composed of the same substance called a pure substance, which is divided into elemental matter and compound.

A mixture, on the other hand, is a mixture of multiple pure substances.

Obviously, milk is a mixture, which is made up of water, fat, phospholipids, proteins, lactose, inorganic salts, etc.

The book says that molecules are made up of atoms, and there is no problem with this statement. In fact, ions are molecules or atoms with dots. Generally, we say that molecules and atoms are electrically neutral, i.e., uncharged.

CO2, O2, H2O are not made of one type of atom, so they are all molecules. Elemental metals are simply made up of metal atoms and no other atoms.

Diamond, i.e. C element, is all made up of C atoms, so it is not a molecule.

Noble gases, which are generally composed of a single atom, were called monoatomic molecules when I was in school, but I don't know if the term has been changed now.

Table salt NaCl is composed of sodium and chloride ions, which are electrolyzed in water to produce sodium and chloride ions. The others mentioned above do not generate ions when they are in water, so they are not ions.

Pure substances refer to chemical compounds that are made up of the same elements. There is no clear definition of a mixture, as long as different substances are mixed together, it is a mixture. Milk is a mixture because it contains a lot of substances like protein molecules and water molecules, etc.

1. A molecule is the smallest unit in a substance that can exist independently and maintain the physical and chemical properties of the substance. A molecule is made up of atoms, which are bound together into molecules in a certain order and arrangement through a certain force. In the case of water molecules, for example, water is continuously divided until the properties of water are not destroyed, and the smallest unit that appears is a water molecule composed of two hydrogen atoms and one oxygen atom.

Its chemical formula is written as H2O. Water molecules can be divided into two hydrogen atoms and one oxygen atom by electrolysis or other methods, but their properties are completely different from those of water. Some molecules are made up of only one atom, called monoatomic molecules, such as helium and argon, which are both atoms and molecules.

A molecule composed of two atoms is called a diatomic molecule, such as an oxygen molecule (O2), which is composed of two oxygen atoms and is a homonuclear diatomic molecule; The carbon monoxide molecule (CO), which is composed of an oxygen atom and a carbon atom, is a heteronuclear diatomic molecule. Molecules made up of more than two atoms are collectively referred to as polyatomic molecules.

And the ions you're talking about are actually molecules, but they don't work in the same way.

Milk mixture.

1.Molecules, atoms, and ions are all particles that make up matter, and molecules are composed of atoms, and atoms gain and lose electrons to form ions, and atoms gain electrons to form anions, and lose to form cations. Some substances are made up of molecules such as water, and like metals, noble gases are made up of atoms directly, while ionic compounds are made up of ions.

2. Pure matter is a substance composed of the same substance. The simple identification is that only one chemical formula can be written for pure substances.

A mixture is a substance that is made up of a mixture of many substances, and it cannot write a chemical formula.

Milk cannot write a chemical formula so for the mixture.

Molecules are made up of atoms and electrons outside the nucleus. The density of the molecules is different, and the three states (solid-liquid gas) of the substance are constituted. Milk is a mixture.

1 molecules are composed of atoms, atoms can also be composed of substances alone, gases are also composed of molecules, but the molecular voids become larger, rare gases I don't know (the third year of junior high school is not required to master), but salt dissolved in water will ionize sodium ions and chloride ions, so it is composed of ions.

2 mixtures. If you don't understand, you can contact me.

Pure substances can be divided into elemental substances and compounds, elemental substances are a substance with only 1 element, and a compound is a substance that is made up of multiple elements. Whereas, mixtures are made up of a variety of substances. (The easiest way to distinguish between purity and mixture:.)

Pure substances can be expressed by chemical formulas, whereas mixtures cannot. Milk is a cloudy emulsion and is a mixture. Molecules are made up of atoms, and general metal elements and noble gases are composed of atoms, and ions are caused by the loss of electrons outside the nucleus, making them dotted.

2.Pure substances can be expressed by chemical formulas, while mixtures cannot be expressed by chemical formulas.

Milk belongs to the mixture.

1.Choose C. After adding water, silver chloride is insoluble in water and can be separated by filtration operation; Sodium hydroxide solution is added to react with ferric chloride to form a reddish-brown precipitate of iron hydroxide, which is separated by filtration; Then add hydrochloric acid to the filtrate and iron hydroxide respectively, you can remove the excess sodium hydroxide solution, iron hydroxide and hydrochloric acid neutralize the reaction to produce water and iron chloride, and then the liquid is heated and evaporated water (at the same time the excess hydrochloric acid can be removed) to obtain three pure substances.

2.I choose DFrom Fe+H2SO4=FeSO4+H2 (gas overflow) Zn+H2SO4=ZNSO4+H2 (gas overflow), it can be seen that because the amount of dilute sulfuric acid is sufficient, the mass of hydrogen produced is determined by the amount of iron and zinc (that is, the number of atoms), and one atom of iron and one atom of zinc produce hydrogen of equal mass (one molecule), so comparing the relative atomic numbers of iron and zinc, we can see that iron is 56 and zinc is 65, so the number of atoms of iron and zinc iron of the same mass is more, So the left side emits more mass of hydrogen than the right side, that is, the left side of the balance is less than the right side, so the balance is biased to the right.

There is a metal activity table to know that zinc is more active than iron, so the right side reacts first, so the balance initially deviates to the left, and then the balance deviates to the right after the left side also reacts.

1.Silver chloride is insoluble in water, sodium chloride and ferric chloride are soluble in water, and water is used first.

Then you can find a way to precipitate ferric chloride first, filter it, and then reduce it to ferric chloride.

Then the ferric chloride is precipitated with sodium hydroxide solution, and then reduced with hydrochloric acid.

So choose C2The order of metal activity zinc is iron, so the reaction between zinc and dilute sulfuric acid is more intense than iron, the release of hydrogen is fast, and the mass is reduced quickly, so the weight on the left is the weight on the right, so it is always biased to the left, and a is selected

1. Answer: C

a, d, nitrate ions are introduced, and new impurities are generated.

b. Ferric chloride becomes iron hydroxide, not separation.

c. Add water - filter (separate silver chloride) - add sodium hydroxide (precipitate iron hydroxide) - filter - filtrate is sodium chloride solution (solid can be obtained by evaporation or crystallization) - precipitate and add hydrochloric acid to produce iron chloride (the substance is separated).

2. Answer: c

First, determine which side the balance will ultimately tilt and analyze the chemical reaction

fe+h2so4=feso4+h2；zn+h2so4=znso4+h2

Left mass increases: (

Right mass increases: (

The reaction rate of zn and acid is slower, and the gas produced is also slower, and the substances are added together, so the mass on the left decreases faster, and the balance is biased to the right at the beginning. Then conclude that the balance is always tilted to the right. Answer C

1,。It is possible to detect whether a substance conducts electricity by dissolving it in water, because ionic compounds ionize into anions and cations in water, making the aqueous solution conductive.

2.No, the relative atomic mass of a substance or the relative atomic mass of an element must be known3This one. There are several elemental symbols, and there are several elements composed of them. Such as NaHCO3, which is composed of the elements of Na H C O.

There are -3 0 1 2 3 4 5 valences, and if they are common, they are -3 0 2 4 5.

The 3-valent ones have NH3 NH4+

The 0 price is, of course, n2

2 valenceの

4 is NO2

The 5-valent is HNO3 N2O3

The anhydride of Hno3 is N2O3 and not NO2

1.See if it conducts electricity ...... in the molten state

2.Probably not.

3.I didn't understand ......

n has -3, +1, +2, +3, +4, +5, and nh3 and nh4+ are all -3

1.See if it conducts electricity ...... in the molten state

2.No. 3.I don't understand it.

and nh4+ are both -3, and the common ones are +2, such as no. -3, as in NH3. +4, e.g. no2. +5, e.g. hno3. The less common ones are +1 and +3

1.See if the compound can be dissociated (usually in water) for substances such as acid-base salts.

2.If you know the mass involved in the reaction, you can know the relative atom-to-mass ratio.

For example, a + b = c Let a b c have a relative atomic mass of x y z

x y z20g 10g 30g

x y z = 20 10 30 = 2 1 3

3.I don't understand what it means to concentrate on an element.

n generally has 5 valence states: -3 +2 +3 +4 +5

Because generally h is +1 valence, so n in NH3 is -3 valence NH4 is ammonium atom cluster and the valence state is +1 where n is -3 valence.

Why not because sulfur combustion consumes oxygen, and the volume of oxygen in the air accounts for 1 5?

Because combustion will produce equal moles of SO2 (Moles belong to high school, it is easy to explain with this smile), that is to say, in terms of the combustion of S, the volume of gas is equivalent to the same as the volume of oxygen consumed

What happens when you stick a burning wooden stick into the co?

CO2 is generated, which starts with a light blue flame and then burns violently in oxygen as CO2 goes out.

6) The answer is, why not?

There are two gases produced, and how do you know which one you are collecting? That's why it's hard to collect.

The answer is b, ** wrong.

I can't really say what's wrong with this kind of thing. All I can say is that this is not how the iron frame is used.

The answer is b, don't understand, solve!

What do you say?,I'm not good at expressing Hongwen.。。。 Think of it as adding 50 degrees of water to 100 degrees of water, and the temperature will drop

Alas, I won't say it, I'm dizzy, I've forgotten about these for a long time, and I remember the last one clearly, but it's hard to say, unless I play ** There are a few questions left, and I didn't answer them if I wasn't sure. Actually, I think you should ask the teacher, and the teacher's answer is the official answer

In addition, I've tried my best.,The last question.,You can ask me.,As long as you're willing to pay for the phone.,So,Dear,If you think it's good.,Just give a satisfaction.。。。 Other questions, it's not that I can't answer them, but I don't touch Zen Tan, I also have to ask my junior sisters, they are in high school, remember clearly

1 This depends on your book, which is in it. I remember a sentence I used to read in chemistry class at that time, "Oxidant is reduced by the increase and loss of the oxidant, and the reduction of the oxidant is reduced, I wonder if you can understand this sentence!" Chemical formula balancing is a technique that uses the valency of the elements, that is, the balance of the number of electrons gained or lost, and the sum of the elements on both sides is equal.

CH4+2O2—ignition—CO2+2 H2O

2 The total number of protons is calculated by adding the number of protons of the constituent elements of the molecule, for example, water is 2*1+16=18, that is, the molecular mass of the water molecule3 The relationship between the number of outermost electrons and the valency is +x x if x is lost and less than or equal to 4 Y y is less than or equal to 4 when y electrons are obtained

4 Here o is -1 and only 1 electron is gained, and that's the magic of chemistry, o ions have two states, -1 and -2

5 Yes, that's what the molecule has a valency of zero.

1. According to the law of conservation of mass, the type and number of atoms before and after the reaction remain unchanged. Trim is carried out.

2. Remember the number of protons of the element, the number of protons of each atom is added, (there are 10 protons in a water molecule, the number of protons in o is 8, the number of protons in one h is 1, and the number of protons in two h atoms is 2, so it is 10).

3. Generally, the number of electrons in the outermost shell and the value of valency are equal, but the lost one is positive and the obtained one is negatively added.

4, In hydrogen peroxide, hydrogen is +1 valence, o is -1 valence, the algebraic sum of the valency of hydrogen peroxide is 0, 5, yes, phosphorus pentoxide P2O5, P valency is positive 5, O valence is negative 2The sum of algebra is (+5x2) + (2x5) = 0