Chemistry concept problems, some chemical problems and definitions

What's the conceptual problem?

The concept must be memorized.

The electronegativity of the elements in the periodic table decreases from top to bottom and right to left, with fluorine (f) having the highest electronegativity and potassium (k) having the lowest electronegativity at the 1st to 20th element entry surfaces. Definition of addition polymerization: the polymerization of multiple monomeric molecules into a large molecule without losing any small molecules (e.g., H2O).

HCL) Definition of standard combustion enthalpy: the enthalpy change of 1 mole of a substance when it is completely burned in air in the standard state (25 degrees 298K, 1 atmosphere pressure (atm), the substance is in the standard state). Definition of enthalpy change in the standard:

In the standard state, acids and bases neutralize each other to produce an enthalpy change of 1 mole of water. Definition of enthalpy change of standard formation: In the standard state, the enthalpy change when a constituent element produces 1 mole of the substance.

Definition of standard dissolution enthalpy: The enthalpy change of 1 mole of a substance dissolved in water to form an infinitely diluted solution in the standard state. 2012-06-13 12:

32:21 Supplement: Definition of standard enthalpy of combustion:

The enthalpy change of 1 mole of a substance when it is completely burned in oxygen in the standard state (25 degrees 298 K, 1 atmosphere pressure (atm), the substance is in its standard state).

The standard enthalpy of dissolution is the enthalpy change that occurs when a crystal is dissolved sufficiently to produce an infinitely diluted solution.

F (fluorine) is the element with the highest electronegativity, and the lowest is not to be remembered. Standard combustion enthalpy is 1 mol of compound, which is the enthalpy change of oxygen when it is completely combusted, Standard neutralization of enthalpy is the enthalpy of acid and alkali neutralization, which produces 1 mol of water, Standard enthalpy of combustion, which is the enthalpy of the formation of 1 mol compound of this component Others forgot.

Reference: chem's knowledge

n(t hydrocarbon) =

n(h)=n(c)=

Molecular formula of this benzene homologue.

for c9h12

There is no tetrachloride, which means that there are 3 methyl-CH3 on the benzene ring, and the position of the three methyl groups on the benzene ring is.

And. and 1,3,5-three cases.

According to the chlorinated substances on the benzene ring, there are three kinds of dichloride to be danced, ==".

The structure of this hydrocarbon is simply as follows.

1,2,4-trimethylbenzene, write your own structure simplified.

Wrong. Metallicity often indicates an element's tendency to lose electrons; Non-metallicity often indicates the tendency of an element to acquire electrons.

1 Oxidation is a part of measuring non-metallic properties, but not all, non-metallic properties also include electronegativity, affinity energy, ionization energy, etc.

2. The relationship between reduction and metallicity is basically the same as above. Metallicity refers to the liveliness of metals, which is manifested in the fact that electrons are easily lost in chemical reactions. So all metals have reducibility.

The strength of the metallicity is judged by how easily it is to lose electrons. However, there are also many non-metals that are reducible, for example, when carbon, sulfur, etc. react with oxygen, they all show reducibility.

Non-metallic is the ability to gain electrons, oxidation, metallicity is the ability to lose electrons, which is reductive. Wherever it goes, too.

This can be understood in high school.

It is not the former because of the metathesis reaction that occurs due to the difference in volatility.

The latter is different because of the boiling point.

Difficult volatile acids to make volatile acids.

1.Oxidation reaction: The valency of the element increases, electrons are lost, and an oxidation reaction occurs.

Reduction reaction: The valency of the element decreases, electrons are obtained, and a reduction reaction occurs.

2.The essence of the valency change of the element The gain and loss of electrons

3.Quantitative relations.

The relationship between the valence rise and fall number and the number of transferred electrons liter = lost electron, falling = number of electrons gained

The total valence of the increased valence is equal to the total valence of the decreasing valence due to the conservation of electron gain and loss

1.Elevated loss of the reducing agent undergoes an oxidation reaction.

Reducing the resulting oxidant undergoes a reduction reaction.

2.Electron gain or loss or shift of electron pairs.

3.In general, the number of valence rises (or decreases) of each reducing agent (or oxidant) multiplied by the coefficient of the part involved in the redox reaction in the chemical reaction equation is added to equal the number of transferred electrons.

Equal to the conservation of electrons for gain and loss.

Remembering the following mantra can solve these problems.

1, the valency increases, is oxidized, as a reducing agent, oxidation reaction occurs, the formation of oxidation products 2, the valency is reduced, is reduced, as an oxidant, the reduction reaction occurs, the generation of reduction products 3, the essence of the redox reaction is the gain and loss of electrons, characterized by the change of valency 4, in the redox reaction, the number of electrons gained and lost is equal, and the total number of increased valency is equal to the total number of reduced valency.

Our teacher said a good method: pure matter is just a chemical composition, such as NaCl, acetic acid, etc., which can be written with chemical formulas; A mixture is composed of 2 or more pure substances, such as a so-and-so solution (which is composed of a solute and a solution), and the chemical formula cannot be written. As for the color of the chemical you said, this is to be memorized, you can't figure it out, it's not familiar with it; Which is the main ingredient of such and such a thing is also backrest, which your teacher should talk about in class, or in your teaching aids.

Chemistry is a subject that is relatively small and memorizes more.