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

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


electron
electron m

Electron. Electrons are very small particles with a very small mass (about 1/1840 of the mass of a proton), have a negative charge, and move around the nuclei of atoms. Its symbol is -e

When atoms lose or gain electrons, they turn into ions:

Gain ← stalagmites negative anions, e.g
S2Br-02-CI-

Loss of ← positive stalactite cations, e.g
Al3+ Fe2+ H+ Na+

Electric current is electrons moving through a conductor. The way electrons are arranged in an atom is called electronic configuration.


electronicegativity
electronic activation f

.

Kahr negativity. The electronegativity of an atom is its ability to attract electrons to itself through a chemical bond.

Electronegativity increases across the period (of the periodic table and up the group).

It is concluded from this that fluorine is the most negatively electroactive atom.

electronic configuration (arrangement) electronic configuration

Electronic collection. Electrons revolve around the nucleus of the atom. This movement takes place in clearly defined orbital regions within the atom. Electrons are visualized as being arranged in orbits, or in shells, each shell containing a maximum number of electrons.

Cover number 1 - 2 - 3 - 4 - 5

The maximum number of electrons is 2 - 8 - 18 - 32 - 50
As we move through the periodic table, the number of electrons in an atom increases by one as the atomic number increases. The shells are filled with electrons one by one: first, then... and so on, so that the electrons go to the region of the atom with the lowest energy. I have given the electronic configuration for some of the elements mentioned in this book, such as sodium 2.8.1, meaning that the two shells are full and shell 3 contains one electron. There are different types of formations in the periodic table. For example: elements of the group group | It always has an electronic combination that ends in 1:
2.1 Lithium
2.8.1 Sodium

The Vil halogens group has a different pattern that practically ends with 7 (the number of the group):

2.7 Fluorine
2.8.7 Chlorine
2.8.18.7 Brom


electroplating
dépôt m electrolytique

Electroplating. If a metal object serves as the cathode in an electrolysis whose electrolyte contains metal ions, the object can be coated with a very thin layer of metal. Certain conditions must be controlled well, such as: current, electrolyte concentration, and temperature.

Electroplating is usually used either for the purpose of protection, such as coating bicycle handlebars and car bumpers with chrome and coating food containers with tin, or for the purpose of decoration, such as coating knives and antiques with silver, coating jewelry with gold, etc.


electrovalent bond
Liaison f electrovalente

Electrostatic bond.
See ionic bond.


element
element m

an item . A pure substance that cannot be broken down into something simpler by chemical means. So far, humans have identified 104 elements, most of which are found naturally on Earth, but many of which are also manufactured in laboratories through nuclear reactions. All elements have a unique number of protons in their atoms. There are three categories of elements:

Minerals such as iron
No minerals like oxygen
Metalloids such as arsenic


empirical formula
Formula of empire

Empirical formula. Shows the empirical formula of a compound
The atoms in the molecule in their simplest ratio:

Compound - molecular formula - empirical formula

ETN _ CH2 _ C2H4

Butane __ C2H5 _ C4H10

Propane _ C3H8 _ *C3H8

Etanic acid _ CH₂O _ C2H4O2

* In some examples, the empirical and molecular formulas are identical.
See molecular formula and composition percentage.


endothermic reaction f endothermic reaction

Endothermic reaction. A reaction in which heat energy is taken from the surroundings when the reaction occurs. Or a drop in temperature occurs when the reaction occurs, as in the case of dissolution of sodium azotate in water:

NaNO3 (solid) - NaNO3 (aqueous)

Or that the reaction requires a constant supply of thermal energy:

CaCO3 (solid) - Cao (solid) + CO2 (gas)

When endothermic reactions occur, the energy of the product bonds is higher than the energy that was present in the bonds of the reactants.