CHARACTERISTIC OF CHEMISTRY REACTION

1. Color changes occur
In a chemical reaction, reactants are converted into products. Changes that can occur due to the termination of the bonds antaratom reactants and formation of bonds that make up bru product. Energy required to decide ties. To form a new bond, release some energy.Thus, the chemical reaction energy changes.
Chemical reactions that produce energy in the form of heat is called exothermic reaction.Reactions that absorb heat energy is called endothermic reactions.
Example: Fire can warm the body when breathing cold and the heat released in the body due to exercise so the body becomes cold.
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2. Temperature changes occur
In a chemical reaction, reactants are converted into products. Changes that can occur due to the termination of the bonds antaratom reagents and formation of new bonds that form the product. Energy required to decide ties.
Chemical reactions that produce energy in the form of heat is called exothermic reactions, whereas reactions that absorb heat energy is called endothermic reactions.
Chemical reactions occur in a space that we call dbngan system, the place is called with the environment outside the system.
In exothermic reactions, heat transfer occurs from sisitem into the environment.
In endothermic reactions occur transfer heat energy from the environment to the system.
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3. The precipitate formation occurs
When the reaction of two solutions in a test tube, sometimes forming an insoluble sneyawa, solid, and separated from the solution. The solid is called the precipitate (precipitate)
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4. Gas formation occurs
Simply put, the chemical reaction of gas that is formed is shown by the presence of bubbles in the solution are reacted. The presence of gas can be known from the typical smell, such as acid sulfide (H2S) and ammonia (NH3), which stinks.

Atom .

Atom is a basic unit of matter, which consists of atomic nuclei and negatively charged electron cloud that surrounds it. The nucleus consists of positively charged protons, and neutrons are electrically neutral (except hydrogen-1 nucleus, which has no neutrons). The electrons in an atom bound to the nucleus by electromagnetic force. As well as a set of atoms can bind to each other, and form a molecule. Atom that contain the number of protons and electrons the same neutral, while containing a number of different protons and electrons are positive or negative and is referred to as ions. Atoms are grouped based on the number of protons and neutrons contained in the nucleus. The number of protons in an atom determines the chemical element the atom, and the number of neutrons determines the isotope of the element.
The term comes from Greek atom (ἄτομος / Atomos, α-τεμνω), which means it can not be cut or something that can not be subdivided. The concept of atoms as a component that can not be subdivided first proposed by the philosophers of India and Greece. In the 17th century and into the 18th, the chemists laid the foundations of this idea by showing that certain substances can not be subdivided further using chemical methods. During the late 19th century and early 20th century, physicists managed to find the structure and components of subatomic particles in atoms, proving that the 'atom' is not can not be subdivided. The principles of quantum mechanics used by physicists and then successfully model the atom. [1]
In everyday observation, the atom is considered a relatively very small objects that have mass also proportionally smaller. Atom can only be monitored by using special equipment such as atomic force microscopy. More than 99.9% of the mass of atoms centered on the nucleus, [note 1] with protons and neutrons are almost the same mass. Each element has at least one isotope with unstable nuclei, that can undergo radioactive decay. This can lead to transmutation, which change the number of protons and neutrons in the nucleus. [2] Electrons are bound to contain a number of atomic energy level, or orbital, which is stable and can undergo transitions between these level by absorbing or emitting photons that correspond to differences between the energy level. Electrons in atoms determines the chemical properties of an element, and influence the magnetic properties of these atoms.
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With so much history about the atom,,,, until now I do not know for certain who themember's name was first ????? Atom and why his name should be an atom??