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A Tabela Periódica e Elementos Orgânicos
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…
Estrutura Atómica
All matter is composed of atoms, the smallest individual units of elements. Each atom is made up of three subatomic particles: protons, neutrons,…
Comportamento dos Eletrões
Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside…
Modelo Orbital dos Eletrões
Orbitals are the areas outside of the atomic nucleus where electrons are most likely to reside. They are characterized by different energy levels,…
Moléculas e Compostos
An atom is most stable when its valence shell—the outermost energy shell that contains electrons—is full. Most elements do not…
Formas Moleculares
The shape of a molecule contributes to its function and its interactions with other molecules. Over the years, many different models have been…
Esqueletos de Carbono
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,…
Reações Químicas
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…
Isótopos
Elements have a set number of protons that determines their atomic number. For example, all atoms with eight protons are oxygen. However, the number…
Ligações Covalentes
When two atoms share electrons to complete their valence shells they create a covalent bond. An atom’s electronegativity—the force with…
Ligações Iónicas
When atoms gain or lose electrons to achieve a more stable electron configuration they form ions. Ionic bonds are electrostatic attractions between…
Ligações de Hidrogénio
Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has…
Interações de Van der Waals
Van der Waal interactions are nonspecific attractions created when one atom comes close enough to another one to disturb its electrons—inducing…
Estados da Água
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…
Solventes
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…
Reações Redox
Oxidation-reduction, or redox, reactions change the oxidation states of atoms via the transfer of electrons from one atom, the reducing agent, to…
Adesão
Adhesion occurs when one type of molecule is attracted to a different kind of molecule. Water exhibits adhesive properties in the presence of polar…
Coesão
Cohesion is the attraction between molecules of the same type - such as water molecules. The partially charged negative oxygen of one water molecule…
Calor Específico
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…
Vaporização
Vaporization changes a liquid substance into a gaseous or vaporous substance. To achieve this, kinetic energy must be greater than the intermolecular…
Diferenciais efeitos de drogas hipolipemiantes na morfologia das partículas de colesterol de modulação
Treatment of dyslipidemia patients with lipid-lowering drugs leads to a significant reduction in low-density lipoproteins (LDL) level and a low to…
Ensaio de efluxo do colesterol
Cholesterol content of cells must be maintained within the very tight limits, too much or too little cholesterol in a cell results in disruption of…
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