Diego Joel Becerra González

Diego Joel Becerra González

Bimestral Review

In the periodic table, elements are classified in three; Metals, Nonmetals and metalloids. Also elements are in ordered in groups and periods. The number o group will tell you how many valence electrons an element has. These are in charge of bonding. The valence electrons can be graphically represented by the electron dot structure. Depending on the valence electrons of an atom it will lose or gain electrons to form the octet rule, that consist to reach an noble gas configuration filling the “s” an “p” sub-levels produce an overall neutral charge. An ion is an atom or group of atoms that has a positive or negative charge. When an atom loss of electrons to become stable it produces a cation, a positively ion. The element that gain electrons become a negatively charge ions called anion.

The ionic bonding is an electrostatic attraction that holds ions together in an ionic compound between 2 elements. Ionic compounds are composed by metals and nonmetals. Also they are composed by cations and anions so the total positive charge will be equal to the total negative charge.  One of the properties of ionic compounds is that most ionic compounds are crystalline solid at a room temperature and generally have high melting points. They have a coordination number is the number of ions off opposite charge that surround the ion on the crystal. Formula unit is the lowest whole number ratio of ions in an ionic compound.

Another type of bonding is bonding in metals called metallic bonging. Which consist of the attraction of free floating valence electrons for the positively charged metal ions, this is what hold metals. Some properties of metals are: that 80% of the elements are metals, are good conductors of heat and electric current, they have the ability to reflect light, and they are ductile and malleable. There are the alloys too. Which are mixtures of 2 or more elements, and at least one is a metal.

Other type of bonding is the covalent bonding, which are molecular compounds were only nonmetals participate. A molecule is two or more atoms bonded by sharing electrons (covalent). This means that if one atom has 6 electrons it will be too from the other atom because they are sharing their atoms. When two atoms held together by sharing a pair of electrons it is called a single bond. If it is shared two or three pairs is called double or triple covalent bond to form a noble gas electron structure. A molecular compound is composed of two or more nonmetal atoms. The ones that are made of two atoms if form a diatomic molecule. The chemical formula of a molecular compound is the molecular formula. That shows how many atoms of each element are represented. You can see by the electron dot structure some electrons are share but other cannot be share because they are already in a pair. These electrons that cannot be shared are called unshared pair of electron.

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