What are the similarities and differences in the chemical properties of the elemental elements of al

Hydrogen is released by reacting with water.

2na+2h2o=2naoh+h2

Reacts with oxygen.

na+o2=na2o2

Alkali metals are silvery-white (cesium slightly golden-yellow), relatively soft metals, relatively small density, and low melting and boiling points. When they form compounds, they are all positive monovalent cations, and when alkali metal atoms lose electrons and become ions, the outermost shell is generally 8 electrons, but the outermost shell of lithium ions is only 2 electrons.

In ancient Egypt, natural sodium carbonate was called neter or nitrum, and it was used during washing. In the 14th century, the Arabs called the ashes of the plant kali, which gradually evolved to be called alkali, but the difference between sodium and potassium was not clear at this time, and it was collectively called soda (soda). It was not until the 18th century that it was not clear that the bubble alkali obtained from table salt and the potassium alkali obtained from plant ash were not the same thing.

Alkali metals can react violently with water to form strong alkaline hydroxides, and the stronger the reaction ability increases with the increase of atomic weight. In hydrogen, alkali metals are formed as white powdery hydrides. Alkali metals can be burned in chlorine, and only lithium can react with nitrogen at room temperature.

Due to the chemical reactivity of alkali metals, they are generally stored in kerosene or paraffin in order to prevent reaction with water in the air.

Alkali metals are all reactive metals. Alkali metal elements are bound by metallic bonds. Due to the large size of the atoms, only one electron participates in bonding, so the interaction between atoms in solids is weak. Alkali metals have low melting and boiling points and are less hard (e.g., sodium and potassium can be cut with a knife).

The valence electron shell structure of the alkali metal element atom is ns1 and hence the valency is +1. The subouter shell of the alkali metal atom has 8 electrons (lithium is 2 electrons), which has a strong shielding effect on nuclear charges, and the outermost valence electron is far from the nucleus and is particularly easy to lose. Compared with other elements of the same period, alkali metals have the largest atomic radius (except for noble gas elements), the lowest first ionization energy, and the least electronegativity.

Alkali metals are characterized by ionic bonds when they form compounds in bonding.

Alkali metals exist in a chemical form in nature. It is often used as a reducing agent in chemical reactions.

Chemical properties of alkali metals:

1. It is a silvery-white metal, with low density, low melting point and boiling point, and high reactivity under standard conditions.

2. They are prone to losing valence electrons to form cations with a single unit of positive charge.

3. They are generally softer in texture and can be cut with a knife to reveal a silvery-white profile; Due to its ability to react with the oxygen in the air, the profile will quickly lose its luster when exposed to air.

4. Due to the chemical properties of alkali metals are very active, they are generally stored in mineral oil or sealed in rare gases to prevent them from reacting with air or water.

5. In nature, alkali metal elements only have a chemical state and cannot exist in a stable elemental form. Alkali metals can react violently with water to form alkaline hydroxides, and their reaction ability and intensity become stronger with the increase of atomic number.

1.Similarity: The outermost number of electrons is 1

2.Degrading: 1The number of electron layers gradually increases; 2.The melting point gradually decreases; 3.The boiling point gradually decreases; 4.The density showed an increasing trend (but Na>k); 5.The metallicity gradually increases.

3.Main chemical properties of alkali metal elements:1

Reacts with oxygen. Both can react with oxygen, but the combustion product of Li is the ordinary oxide Li2O, while the combustion product of Na is the peroxide Na2O2, and the combustion products of K, Rb, and CS are more complex. 2.

can react with H2O, and the reaction becomes more and more violent. General Formula:

2r+2h2o=2roh+h2 (r is an alkali metal)3In the flame color reaction, sodium is yellow and potassium is purple (through blue cobalt glass).

The density of alkali metals increases with the increase of the number of nuclear charges, the metallicity is enhanced from top to bottom, the elemental reduction is enhanced, the melting and boiling point is reduced, and the density increases. Elemental metallic elements have strong elemental reducibility, cationic oxidation is weak, and elemental non-metallic is the opposite.

However, there is a special case where the density of potassium is less than that of sodium. For potassium, the nucleus gravitational pull on the outermost layer is smaller, and the effect of the increase in volume is greater than that of the increase in relative atomic mass, resulting in a smaller density of potassium than sodium.

Physical properties of alkali metals

The alkali metals are all silvery-white metals with metallic luster (cesium with golden yellow), but when exposed to air, oxide films will be formed due to the oxidation of oxygen, which will reduce the gloss and appear gray.

The density of alkali metal elements is less than that of typical light metals, lithium, sodium, potassium can float on water, and lithium can even float in kerosene.

The crystal structure of alkali metal elements is body-centered cubic packing, with small bulk density, Mohs hardness less than 2, soft quality, excellent electrical and thermal conductivity. Alkali metals can be alloyed with mercury (Hg) to form an alloy (amalgam).

The above content reference: Encyclopedia - alkali metals.

Reaction between metal elements and non-metal elements: Mg+Cl2---MgCl2 basic oxides and acid oxides: Na2O+CO2---Na2CO3 acid and base reaction:

Reaction of HCl+NaOH--- NaCl+H2O metal elemental elements with acid: Fe+2HCl---FeCl2+H2 non-metallic elemental reaction with base: Cl2+2NaOH---NaCl+Naclo+H2O

Reaction of basic oxides with acids: Na2O+2HC---2NaCl+H2OAcid oxides react with bases: CO2+2NaOH--- Na2CO3+H2O acids react with salts:

HCl+AGnO3---AGCl+HNO3 bases react with salts: 2NaOH+CuSO4---Cu(OH)2+Na2SO4

Salt reaction with salt: BaCl2+Na2SO4---BaSO4+2NaCl

Reaction of basic oxides with acidic oxides: Na2O+CO2--- Na2CO3 basic oxides react with acids: Na2O+2HC---2NaCl+H2O acid and base reaction:

Reaction of HCl+NaOH--- NaCl+H2O metal elemental elements with acid: Fe+2HCl---FeCl2+H2 non-metallic elemental reaction with base: Cl2+2NaOH---NaCl+Naclo+H2O

1. The alkali solution can react with the acid-base indicator.

The alkali solution turns blue when it encounters purple litmus (the phenomenon is not obvious, but there is a change), and when it encounters a colorless phenolphthalein solution, it turns red (the phenomenon is obvious).

2. Alkali can react with acid to form salt and water (this kind of reaction is usually called neutralization reaction).

For example, hydrated lime (calcium hydroxide) is commonly used in industry to neutralize wastewater containing excessive sulfuric acid.

ca(oh)2+h2so4=caso4+2h20

3. The alkali solution can react with non-metallic oxides to generate salt and water.

For example, the most common reaction of this type is the reaction of carbon dioxide in the laboratory to test with clarified lime water, but this type of reaction is not a metathesis reaction.

co2+ca(oh)2=caco3↓+h2o

4. The alkali solution can react with the salt to generate new alkali and new salt.

For example, this kind of reaction is common in the preparation of sodium hydroxide in the laboratory, and the reaction between alkali and salt has two requirements, one requires that the alkali and salt involved in the reaction be soluble in water, and the other requires that there is precipitation, gas or water in the product.

ca(oh)2+na2co3=caco3↓+2naoh

There are 4 chemical properties of alkalis, also known as the general properties of alkalis. It is important to note that some properties are only applicable to soluble bases.

Reacts with indicators.

Reacts with acids. Reacts with salt.

Reacts with non-metallic oxides.