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Периодическая таблица и организменные элементы
Elements are the smallest units of matter that cannot be broken down further by chemical processes. There are 118 known elements, but not all of…
Атомная структура
All matter is composed of atoms, the smallest individual units of elements. Each atom is made up of three subatomic particles: protons, neutrons,…
Поведение электрона
Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside…
Орбитальная модель электрона
Orbitals are the areas outside of the atomic nucleus where electrons are most likely to reside. They are characterized by different energy levels,…
Молекулы и соединения
An atom is most stable when its valence shell—the outermost energy shell that contains electrons—is full. Most elements do not…
Молекулярные формы
The shape of a molecule contributes to its function and its interactions with other molecules. Over the years, many different models have been…
Углеродные скелеты
The backbone of all organic compounds is a carbon skeleton. Each carbon atom can make four bonds, and as the carbon skeleton increases in length,…
Химические реакции
A chemical reaction is a process by which the bonds in the atoms of substances are rearranged to generate new substances. Matter cannot be created…
Изотопы
Elements have a set number of protons that determines their atomic number. For example, all atoms with eight protons are oxygen. However, the number…
Ковалентные связи
When two atoms share electrons to complete their valence shells they create a covalent bond. An atom’s electronegativity—the force with…
Ионные связи
When atoms gain or lose electrons to achieve a more stable electron configuration they form ions. Ionic bonds are electrostatic attractions between…
Водородные связи
Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has…
Ван-дер-Ваальсовые взаимодействия
Van der Waal interactions are nonspecific attractions created when one atom comes close enough to another one to disturb its electrons—inducing…
Состояния воды
Water exists in three main states: solid (ice), liquid, and gas (steam). The state water is in depends on the intermolecular forces that draw water…
pH
The potential for a solution to donate or accept hydrogen ions determines whether it is an acid or a base. Acidic solutions donate protons, whereas…
Растворители
A solvent is a substance, most often a liquid, that can dissolve other substances. Here, the substance being dissolved is called a solute. When a…
Окислительно-восстановительные реакции
Oxidation-reduction, or redox, reactions change the oxidation states of atoms via the transfer of electrons from one atom, the reducing agent, to…
Адгезия
Adhesion occurs when one type of molecule is attracted to a different kind of molecule. Water exhibits adhesive properties in the presence of polar…
Срастание
Cohesion is the attraction between molecules of the same type - such as water molecules. The partially charged negative oxygen of one water molecule…
Удельное тепло
A substance’s specific heat capacity refers to the amount of energy required to heat one gram of the substance by one degree. Water has a high…
Испарение
Vaporization changes a liquid substance into a gaseous or vaporous substance. To achieve this, kinetic energy must be greater than the intermolecular…
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