أكاديميا - كولنز - معاجم الجيب العلمية - الكيمياء - انكليزي - فرنسي - عربي الحرف ٢_ s

Academia - Collins - Pocket Scientific Dictionaries - Chemistry - English - French - Arabic Letter 2_ S


silica gel
gel m of silicone

Silica gel. A form of silicon dioxide (SiO2) that can absorb up to 40 percent of its mass from water. Dehydrating agent is used in desiccators, and is also used in packaging to keep goods dry. Cobalt(II) salt can be added to the gel to indicate the presence of...
water. For example:

blue
Cobalt (II) chloride, dry anhydrous COCl2

red
Cobalt (II) chloride is hydrated CoCl2.2H2O


silicon
silicium m

Silicon is a group IV metalloid. It is a very abundant element, and the second most abundant element in the Earth's crust (27.7%), as it is part of the composition of many rocks. Silicon semiconductor occupies the heart of microelectronics technology - the silicon globe. Silicon exists naturally in the form of silicates and silica (silicon dioxide). The mineral quartz is the purest form of silica. Sand is fine crystals of silica with impurities of varying density.


silver
argent m

silver. Transition metal transition metal. It is used in jewelry and decorative purposes, and was used in minting coins. It is often mixed with copper to give it strength. It is an excellent conductor of electricity and heat. When exposed to air, it gradually forms a black film of silver sulfide.

Silver ranks low in the reactivity series, and its oxide is unstable:

Ag2O → 2Ag + O2
(gas) (solid) (solid) heat

Silver halides are also unstable. This feature is used in photography:

2AgBr → 2Ag + Br2
(gas) (solid) (solid) light

single bond
liaison f simple

Single bond. A covalent bond made up of a shared pair of electrons. Examples can be found in all organic compounds and in compounds formed from non-metals, such as:

H-CI
Hydrogen chloride
Durability
ammonia

slaked lime (Ca(OH)2)
That's it

Lime hydrated. It is calcium hydroxide. It can be produced by slaking lime with water:

Cao (solid) + H2O (liquid) → (Ca(OH)2 (solid)

The solution of hydrated lime in water is known as lime water, and hydrated lime is used in agriculture and in making mortar.
See calcium compounds.


soap
soap m

Soap. A cleaning agent made by reacting an alkali, such as a sodium hydroxide solution, on naturally occurring esters.
See saponification.
Example of a soapy detergent molecule
The hydrocarbonic end of the molecule is hydrophobic. The carboxyl end of the molecule is hydrophilic.
See detergent.


sodium
sodium m

sodium. A soft, gray metal in the group group | From the periodic table. It can be easily cut with a knife, revealing a silvery surface that instantly loses its luster. Sodium is preserved under the oil due to its interaction with air and water. It is highly reactive with water and non-metals. For example:

2Na + 2H2O→ 2NaOH + H2
(gas) (water) (liquid) (solid)

2Na (solid) + Cl2 (gas) → 2NaCl (solid)

The metal ions give a yellow/orange test flame.
Sodium is extracted from molten sodium chloride by electrolysis.

2NaCl (liquid) → 2Na (liquid) + Cl2 (gas)

Sodium chloride is obtained from rock salt, and sodium metal is used as a coolant in the fast-breeding nuclear reactor and in making the gasoline additive tetraethyl lead (Pb(C2H5)4), which is used to raise the octane rating in fuel. Sodium is also used to extract metals such as titanium:

TiCl4 + 4Na → Tí + 4NaCl
(liquid) (solid) (liquid) (liquid)

Sodium ions (Na+) are important components of animal tissue fluids. This is why sodium chloride (table salt) is added to food during the cooking process.