A junior high school chemistry question about the elements

Water is made up of H20 molecules - What is the matter with ions CO2 is made up of CO2 molecules Where do C4+ ions O2- ions come from? If sulfurous acid is generated in the reaction, it will generally become SO2+H2O, you know what the reaction produces, you are a junior high school, and you do not have high requirements for redox reactions, which generally does not need you to judge.

Definition of element: A general term for a class of atoms with the same number of nuclear charges (i.e., the number of protons in the nucleus).

1.The proton number of the three atoms of deuterium, deuterium and tritium is 1, and the number of neutrons is , and these three atoms are a class of atoms with the same number of protons, collectively known as hydrogen elements. Another example:

A carbon atom with a proton number of 6 and a neutron number of 6 and a carbon atom with a proton number of 6 and a neutron number of 7 are both carbon elements because both atoms have the same number of protons.

2.Types of elements: There are more than 100 types in total. By mass, the top four elements in the earth's crust are oxygen, silicon, aluminum, and iron.

3.Classification of elements: It can be divided into two categories: metallic elements and non-metallic elements. Carbon, hydrogen, oxygen, etc. are non-metallic elements, and iron, copper, and aluminum are metallic elements.

4.The most essential difference between one element and another is that the number of nuclear charges (i.e., the number of protons) is different.

5.The characteristics of the Chinese name of the element: metal elements except mercury are next to "gold", and non-metallic elements are added to "stone" and "gas" according to their elemental state of existence under normal circumstances. Therefore, based on the "side", it is possible to determine which type of element they belong to.

6.Elements are macroscopic concepts, and only talk about types, not numbers. The difference and connection between elements and microscopic concepts such as molecules, atoms, ions, etc.

7.When discussing the composition of matter, it is generally described as "what element is made up of such and such a substance", which only involves categories, and does not mean quantity. Such as:

Water is composed of hydrogen and oxygen (or water is composed of hydrogen and oxygen); Iron is made up of the element iron.

1) Na2CO3CO2CA (2) caustic soda.

or caustic soda or caustic soda.

3) Ca(OH) 2 Na 2 Co3 CaCo 3 2NaOH Metathesis (1) Since F is a common building material and can react with water to form a colorless solution, it can be inferred that F is Cao and B is Ca(OH) 2; The precipitate C generates Cao and colorless gas E at high temperature, and it can be seen that C is CaCo3 and E is Co2. A and Ca(OH)2 form D and CaCO3, and it is known that A is the sodium salt of the three elements, so it can be known that A is Na2CO3 and D is NaOH; (2) D is NAOH, commonly known as caustic soda or caustic soda or caustic soda; (3) A is the chemical equation of Na2CO3, C is CaCO3, and A is converted to C.

is Ca(OH)2Na2CO3CaCo3NaOH, which belongs to metathesis reaction.

Is it a compound: or a gas compound: or is it containing elements C and O: or is it a ratio of 1:2 to the number of particles?

So the writing is common in junior high school.

NaCl sodium chloride.

NaOH sodium hydroxide.

na2co3

Sodium carbonate. nahco3

Sodium bicarbonate. bacl2

Barium chloride. baso4

Barium sulfate. ba(oh)2

Barium hydroxide. agno3

Silver nitrate. ca(oh)2

Calcium hydroxide. Precipitate: baco3

Barium carbonate. baso4

Barium sulfate. caco3

Calcium carbonate. agcl

Silver chloride. Acid: H2SO4

Sulphuric acid. hcl

Hydrosulfuric acid (hydrochloric acid).

HNO3 nitric acid.

o2，so2,so,co，so3，ch4、h2，no2、o3,cl2,hcl,nh3

h2s,c2h4

c2h2,no

Common gases that I know.

O2 (oxygen).

CaCO3 (calcium carbonate).

Ca(OH)2 (calcium hydroxide.

KMNO4 (potassium permanganate).

MNO2 (manganese dioxide), K2mnO4 (montoic acid methyl), H2O2 (hydrogen oxide).

H2O water), MGO (magnesium oxide).

I don't know if you're enough.

All the numbers are at the bottom right of the previous letter.

Write small. You should know.

Since you don't have enough.

I'll write a little more. P2O5 (O in the middle is non-zero) (phosphorus pentoxide, agno3, silver nitrate).

mnO2 manganese dioxide).

CuCl2 copper chloride).

CaO2 calcium oxide).

CuO2 copper oxide).

clo2 chlorine oxide).

C2H6O (alcohol).

SO2 (sulfur dioxide).

SO3 (sulfur trioxide).

NH3 (ammonia).

CH4 (methane).

NO2 (nitrogen dioxide).

H2S (hydrogen sulfide).

MgSO4 (magnesium sulfate).

H2SO4 (dilute sulfuric acid).

I don't know about the rest.

Okay?

The number of outermost electrons of the main group element is not 3

Is it a change from 1 to 7!!

The chemical properties are not the same as the noble gas calling element reed.

Who said that the outermost electron number of a group element is three? .

The chemical essence is the breaking of old chemical bonds.

New bond generation.

Accompanied by the transfer of energy.

After the ion obtains an electropure electron, the number of electrons in the outermost shell exceeds the number of electrons that it should have in its original element, and it reaches a relatively stable structure).

This guess silver is a relative spike feast.

High temperature. Electrolysis.

Wait. can break relative stability.

"Compound artemether: C16H26O5 (chemical symbol) is composed of three elements: C, H, and O. ”

This statement is true. Matter is made up of elements, such as water is made up of hydrogen and oxygen.

C16H26O5 is a chemical formula, and the chemical formula has 4 meanings: (macroscopic) for the substance; Represents the elemental composition (microscopic) of the substance, represents a molecule of the substance; Indicates the atomic makeup of the molecule of the substance.

Molecules, atoms really cannot be said to be composed of elements, because molecules are microscopic concepts, while elements are macroscopic concepts.

Here's a picture for you:

It is estimated that you are not clear about the concept and confused, but if you think carefully about the 4 meanings of the chemical formula, you will understand. The chemical formula given in the title also indicates that compound artemether is a substance, which is composed of elements, so this sentence is not wrong.

That's right, isn't this sentence "compound artemether is composed of three elements: C, H, and O", matter is composed of elements, there is no problem, and there is no problem with the sentence "molecules and atoms are not composed of elements".

This chemical symbol not only represents a molecule of compound high encryption, but also can represent a substance of compound high encryption, which is composed of elements.

The composition of pure matter is found in the element, and the pure substance is composed of such and such an element.

A molecule is made up of a certain atom, not to mention the composition, and the atom is made up of the nucleus and electrons, not to mention the composition.

Elements: Only talk about the type, not the number.

Atom: It's about both types and numbers!

The elements speak of composition! Atoms talk about composition!

Molecules can make up new substances!

Atoms can make up molecules, or they can directly make up new matter!

The question refers to this substance, not to this molecule.

Matter can be made up of elements.

1) F fluorine.

Blind companion 2) +5

3) 105* (0 at the end is better not to be omitted).

Mobi stupid 144 = (approximately equal to) =

Just look at the periodic table, because there should be in the back of the book, generally only the first 20, that is, to the fourth cycle of the a-main group.

Others can be left out.

Eight main family elements. In addition, it is important to memorize the active order of metallic elements: potassium, calcium, sodium, magnesium, aluminum, zinc, iron, tin, lead, hydrogen, copper, mercury, silver, platinum.

The top three elements in the earth's crust are o

The metal element AL with the highest content of SIAL is the top three in the human body

The metallic element Ca, which has the highest content of HO, is the top two elements in the air, N

o Compounds are pure substances made up of different elements. Such as gas, CO2, solid, Nacl, liquid, blind, H2O, etc.

Looking at the universe as a whole, the most abundant elements are H and HE

The basic element of all life on earth is C, and the element with the largest variety of substances is C