Classification of matter

ELEMENTS, ATOM, COMPOUNDS, MOLECULAR, and ION

ELEMENT

Elements are chemicals that can not be subdivided into smaller substances, or can not be converted into other chemicals by using ordinary chemical methods. The smallest particles of the element are atoms. An atom consists of an atomic nucleus (nucleus) and is surrounded by electrons. The atomic nucleus consists of a number of protons and neutrons. Until now it is known there are approximately 117 elements in the world. What distinguishes one element from another is the number of protons in the nucleus of the atom. For example, all carbon atoms have protons of 6, while oxygen atoms have 8 protons. The number of protons on an atom is known as the atomic number (denoted by Z).
Atoms of the same element can have different numbers of neutrons; This is known as the isotope. The atomic mass of an element (denoted by "A") is the average mass of an elemental atom in nature. Because the mass of electrons is very small, and the mass of neutrons is almost the same as the mass of the protons, the atomic mass is usually expressed by the number of protons and neutrons in the nucleus of the atom, which is the most abundant isotope in nature. The size of the atomic mass is the unit of atomic mass (smu). Some isotopes are radioactive, and decompose (decay) against the radiation of alpha or beta particles.
The lightest elements are hydrogen and helium. Hydrogen is believed to be the first element in the universe after the Big Bang. All heavy elements are naturally formed (either naturally or artificially) through various methods of nucleosynthesis. Until 2005, known 118 elements are known, 93 elements of which are in nature, and 23 elements are artificial elements. The first artificial element is thought to be the technetium in 1937. All the artificial elements are radioactive with a short half-life, so that the naturally occurring atoms seem to have broken down.
List of elements can be expressed by name, symbol, or atomic number. In the periodic table, also presented a grouping of elements that have the same chemical properties. The naming of the element has long before the atomic theory of a substance, although at that time it is not yet known which is the element, and which is the compound. When atomic theory develops, the names of elements that have been used in the past remain in use. For example, the "cuprum" element in English is known as copper, and in Indonesian it is known as copper. Another example, in German "Wasserstoff" means "hydrogen", and "Sauerstoff" means "oxygen".
The official name of the chemical element is determined by the IUPAC organization. According to IUPAC, the element name does not begin with a capital letter, unless it is at the beginning of a sentence. In the latter half of the 20th century, many laboratories were able to create new elements that had high decay rates for sale or storage. These new element names are also defined by IUPAC, and generally adopt the name chosen by the inventor of the element. This can lead to the controversy of which original research group discovered the element, and delays in naming the element for a long time.
Before chemistry became a field of science, alchemists have established symbols for
both metal and other common compounds. They use abbreviations in diagrams or procedures; And without the concept of an atom joining to form a molecule. With the development of substance theory, John Dalton introduced simpler symbols, based on a circle, used to describe molecules.
The currently used system was introduced by Berzelius. In the typographic system, the chemical symbol used is the abbreviation of the Latin name.
For example:
Fe is a symbol for the element of ferrum (iron),
Cu is the symbol for the element Cuprum (copper).
Hg is the symbol for the element hydrargyrum (mercury),
Chemical symbols are used internationally, although elemental names are interlocuted. The first letter of the chemical symbol is written in capital letters, whereas the next letter (if any) is written in small letters. Non-elemental elements, especially in organic and organometallic chemistry, often use symbols that are inspired by chemical element symbols. Here is an example:
Cy - cyclohexyl; Ph - phenyl; Bz - benzoyl; Bn - benzil; Cp - Cyclopentadiene; Pr - propyl; Me - methyl; Et - ethyl; Tf - triflate; Ts - tosil; Hb - hemoglobin.



ATOM

Atoms are the basic units of matter consisting of an atomic nucleus surrounded by a cloud of negatively charged electrons. The nucleus of the atom contains a mixture of positively charged protons and neutrons with neutral charges (except for Hydrogen-1 without neutrons). The electrons in an atom are bound to the nucleus of an atom by an electromagnetic force. Similarly, a set of atoms can bind to each other forming a molecule. Atoms containing the same number of protons and electrons are neutral, while those containing different numbers of protons and electrons are positive or negative and are ions. Atoms are grouped by the number of protons and neutrons in the nucleus of the atom. The number of protons on the atom determines the chemical element of the atom, and the number of neutrons determines the isotope of the element.
The term atom comes from the Greek? T? Μ ?? / átomos, a-teμ ??, meaning it can not be cut or something that can not be divided again. The concept of atom as an indivisible component was first proposed by Indian and Greek philosophers. In the seventeenth and eighteenth centuries, chemists laid the foundations of this idea by showing that certain substances could not be further divided using chemical methods. During the late nineteenth and early twentieth centuries, physicists managed to discover the structure and subatomic components within the atom, proving that 'atoms' are not indivisible. The principles of quantum mechanics used in physicists then succeeded in modeling atoms.
Relative to everyday observations, atoms are very small objects with equally small masses. Atoms can only be monitored using specialized equipment such as scanning tunneling microscopes. More than 99.9% atomic mass centers on an atomic nucleus, [note 1] with protons and neutrons of about the same mass. Each element has at least one isotope with an unstable nucleus that can undergo radioactive decay. This can lead to transmutations that change the number of protons and neutrons at the nucleus. [3] The electrons attached to the atoms contain a number of energy, or obrital, levels that are stable and can transition between them by absorbing or emitting photons corresponding to the energy difference between levels. The electrons in the atoms determine the chemical properties of an element and affect the magnetic properties of the atom.
Many other elements are created by humans, but they are usually unstable and spontaneously transform into a stable natural chemical element through the process of radioactivity.


COMPOUND

Chemical compounds are substances by chemical means can still be described into other substances more simple. It is a chemical formed from two or more chemical elements, with a fixed ratio that determines the composition. For example, dihydrogen monoxide (water, H2O) is a compound consisting of two hydrogen atoms for each oxygen atom. Generally, this fixed ratio must remain due to its physical properties, not the ratio of which humans choose. Therefore, materials such as brass, superconducting YBCO, semiconductor "aluminum gallium arsenide", or chocolate are considered as a mixture or aloy, not a compound.
The distinguishing feature of a compound is that the compound has a chemical formula. The chemical formula describes the atomic ratio in the substance, and the number of atoms in its single molecule (hence the chemical formula of ethene is C2H4 and not CH2) The chemical formula does not mention whether the compound consists of molecules, for example, sodium chloride (salt, NaCl is an ionic compound ).
Compounds can be manifest in several phases. Most compounds can be solids. Molecular compounds may also be liquids or gases. All compounds will break down into smaller compounds or individual atoms when heated to a certain temperature (called decomposition temperature).
Every chemical compound that has been described in the literature has a unique identification number, the CAS number.
Compound type:
A. acid
B. Bases
C. Ionic compounds
D. salt
E. Oxide
F. Organic compounds


MOLECULE
A molecule is a composite of binding atoms. Molecules can be divided into 2, namely:
1. molecule unsure: consists of atoms of a kind. Example: 1 molecule of hydrogen gas consists of 2 hydrogen atoms that bind each other.
2. molecule compounds: two or more atoms of different elements combine to form molecules. Example: The water molecule consists of 2 atomhydrogen and 1 oxygen atom.