High II Chemistry, structural formula Molecular formula

Now that you have analyzed the molecular formula, according to the molecular formula C3H6O, you can know that its unsaturation is (2 3+2-6) 2=1, there is a ring or double bond in the molecule, and then according to infrared and nuclear magnetic resonance, you know that there is "c=ch and -oh" in the molecule, and a double bond (-c=c-) has been written, the unsaturation is 1 degree, and 2 c atoms and 1 o atom are written, you only need to add 1 c atom, and c=c is directly connected to -oh is unstable, Write the C atom that needs to be added between the two, and add the H atom to complete it.

C3H6O to CH2=CH-CH2OH

First, calculate the unsaturation of this organic matter (2x3+2-6) 2 =1, infrared spectroscopy and nuclear magnetic resonance show that the molecule contains a carbon-carbon double bond (unsaturation is 1), first ch2=ch2, in the question c=ch-oh(what? Then add groups to the left and right.

The mass of soda lime weight gain is the amount of carbon dioxide produced by the full combustion of organic matter, and the ratio of carbon dioxide in organic matter should be obtained by the ratio of the amount of water produced to carbon dioxide substances. And then it has to contain a hydroxyl group and a carbon-carbon double bond, and you can write it in proportion.

Do you think that hydroxyl is added to C=C,,, such a substance is unstable and easily decomposed, so hydroxyl is added to the alkyl group.

To put it simply, the structure is the (complete) molecular structure, such as methane, and you have to stretch all the 4 hs out.

The simple structure is to simplify the structural formula, and the groups can be combined, such as --oh can not be stretched.

The molecular formula is simpler, you don't need to show their groups, just show the number of elements and atoms that should be there, such as C2H4

The electrosensitive aphony formula is similar to the structural formula, but the electrons of the atom should be represented in the form of electron pairs, that is, the final 8 electrons or 2 electrons are stable, which is more stable than the bridge oak such as: o::c::o::

The structure of organic matter is the core of organic chemistry, and the key is to determine the molecular formula and structural formula of organic matter. Next, I have sorted out the determination of the molecular formula and structural formula of chemical organic compounds in the 2017 college entrance examination for you, let's take a look.

<>1.It is determined by qualitative or quantitative experiments: the structure of a substance determines the properties, and the properties reflect the structure.

Due to the existence of isomers in organic matter, the structure of a substance is determined mainly by using the special properties of the substance to determine the special structure of the substance, that is, to determine its structural formula through qualitative or quantitative experiments. It mainly determines the functional group of the substance, and the location of the functional group.

2.Determination of the law of valence bonds: Some organic substances have only one structure according to the law of valence bonds, and their structural formulas can be determined directly by molecular formulas.

For example, C2H6, according to the 4-valent carbon element and the 1-valent hydrogen element, the carbon-carbon can be directly connected, and it can be seen that there is only one missing Zheng species structure: CH3-CH3; In the same way, CH4O, according to the law of valence bonds, CH4O also has only one structure: CH3-OH.

The general steps to determine the structural formula of an organic substance are as follows:

Determine the molecular formula of the organic matter first;

According to the molecular formula, write the possible structural formula according to the valency;

You can do both.

The simple structure is a simple expression of the structural formula (usually only applicable to pure substances in molecular form, such as organic molecules), which should express the functional groups in the substance: as long as the carbon-hydrogen single bond is omitted, the carbon-carbon single bond can be omitted or not, for example, the simple structure of propane is ch3ch2ch3, ethylene is ch2=ch2, etc. However, the carbon-carbon double bond and triple bond must not be omitted.

Carbon-oxygen double bonds can be omitted, such as formaldehyde HCHO.

Molecular formula (molecular

formula) is a chemical formula that uses elemental symbols to express the composition and relative molecular weight of substances (elemental, compound) molecules. Some substances are indeed made up of molecules, which are connected by covalent bonds between atoms within the molecule, and between molecules by van der Waals forces or hydrogen bonds, and these substances have molecular formulas.

The molecular formula is different from the simplest formula, and for compounds, their molecular formula is an integer multiple of the simplest formula, or the relative molecular mass is an integer multiple of the simplest formula. The simplest formula is the same as the molecular formula only if the relative molecular mass and quantity of the minimum formula are the same, and then the minimum formula is the molecular formula.

It is recommended to use the simple structure.

1.There are many electrons outside the nucleus that rotate around the nucleus at high speed, how to say, each kind of atom will need a specific number of electrons outside the nucleus to achieve the most stable state, in order to achieve a stable state, to put it in layman's terms, some atoms will rob other people's electrons to form stable ions, and others, they will share electrons with other atoms, which forms a shared electron pair. When it is expressed by structural formula, ** is used to represent the shared electron pairs between atoms.

It is true that it can draw 4 wires, because it has 4 electrons in its outermost shell, and in order to form an 8-electron stable structure, it also needs to form 4 pairs of shared electrons with others. And "c-c" is just a representation for the convenience of explanation, it represents a carbon-carbon single bond, which is only a part of the structure of a substance, and is incomplete, so this kind of diagram will not be used as the answer in the general exam.

In fact, I think it's okay to understand these things in high school a little bit, and you can also understand them yourself, and sometimes the methods you imagine may be more vivid and practical. Don't deduct some questions

If the carbon atom is surrounded by hydrogen atoms, the chemical bonds can not be written, which is also correct, for example ethylene can be written as ch2=ch2, but note that the omitted chemical bonds can only be single bonds (hydrocarbon, carbon-carbon, carbon-oxygen, etc.), and the atoms still have to be written. C-C is not written in a standard way. At the same time, if the single bond is connected to an atomic cluster, the atomic cluster should be bracketed when omitted.

For example. Isopentane can be written as ch3 (ch3) ch3ch3ch3, and the methyl group in parentheses is the side chain.

Containing C 180 60% 12 = 9, H and O account for 72A The amount of substances consumed by complete combustion of O2 is equal to the amount of substances that produce CO2, indicating that the ratio of H and 0 is 2:1

Molecular formula C9(H20)x=180

x=4 so is c9h804

Containing C 180 60% 12 = 9, H and O account for 72A The amount of substances consumed by complete combustion of O2 is equal to the amount of substances that produce CO2, indicating that the ratio of H and 0 is 2:1

Molecular formula C9(H20)x=180

x=4 so is c9h804

2 points are awarded for the first answer, and reward points and an additional 20 points are awarded for the answer accepted. It is known that the molecular weight of M is 227, which is composed of four elements: C, H, O, and N, and the mass fraction of C, H, and N is in order, then the molecular formula of M is C3H5N3O9

The amount of substances that consume O2 by complete combustion is equal to the amount of substances that produce CO2 It means that the ratio of oxygen atoms to hydrogen atoms in the molecule is exactly 1:2, and the combustion can produce water, so it can be considered that the carbon atoms in A combine with O2 to form CO2

180x60%=108

There are a total of 108 12 = 9 carbon atoms.

The remaining 72 are O and H

This is H8O4

The molecular formula is C9H8O4

The organic molecule contains c 180 60 12 = 9, and the molecular formula is .

c9hxoy

According to the title. a: The amount of substances that consume O2 by complete combustion is equal to the amount of substances that produce CO2 9+x 4-y 2=9

x/4=y/2

x=2yc9h2yoy

9*12+2y+16y=180

y=4 molecular formula.

c9h8o4

If it's hexane, it's five isomers (due to technical problems, you can only write a simple structure, hehe).

1. CH3CH2CH2CH2CH2CH3 n-hexane 2, CH3CH2CH2CH(CH3)2 2-methyl-pentane 3, CH3CH2CH(CH3)CH2CH3 3-methyl-pentane 4, (CH3)2CH2CH(CH3)2 2,3-2-methyl-butane.

5. CH3CH2C(CH3)3 2,2-2-methyl-butane.

CH3CH2CH2CH2CH2CH3 n-hexane (CH3) 2CH2CH2CH3 2-methyl-pentane CH3CH2CH(CH3) CH2CH3 3-methyl-pentane (CH3) 3CCH2CH3 2,2-Dimethyl-butane (CH3) 2CH2CH(CH3)2 2,3-dimethyl-butane.